Machinable copper alloy with high strength

Abstract

A machinable copper alloy comprising beryllium and at least one "N" element. The copper alloy may contain beryllium and has low levels of lead, e.g., no more than 900 ppm of lead.

Description

Machinable Copper Alloy with High StrengthPRIORITY CLAIM

[0001] This application claims priority to U.S. Provisional App. No. 63 / 661,345, filed on June 18, 2024, the entirety of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to copper alloys that are machinable. In one embodiment, the copper alloy may be a copper-beryllium alloy having niobium and / or bismuth. The copper alloy may be processed to provide a machinable copper alloy having enhanced strength characteristics, and preferably ultra-high strength.BACKGROUND

[0003] Copper-beryllium alloys are used in various industrial and commercial applications due to their strength, resilience, and fatigue resistance. Copper-beryllium alloys have been widely used as high strength spring materials, electrically conductive materials, etc. For example, products made from copper-beryllium alloys are used in computers and electronics, fasteners, telecommunication products, valve seat, voice coil motor (VCM) and / or optical image stabilization (OIS) technologies where various mechanical and electrical designs are used to provide high-resolution, auto-focus, optical zooming camera capability in mobile electronic devices. When used for these technologies, the copper-beryllium alloy products are typically cut into thin strips so as to be able to fit within confined spaces to increase portability and functionality of the mobile electronic device. The small size of the strip demands very high strength in the copper-beryllium alloy. As the electronic devices become more compact, the strength requirements for the copper-beryllium alloy products continue to increase.

[0004] A number of commercial copper-beryllium alloys are known, including those bearing Copper Development Association designations C17500, C17510, C17000, C17200, C17300 as well as C81300, C82100, C82200 and C82400. These alloys contain varying amounts of beryllium and other alloying elements such as cobalt, nickel, or silver. US Pat. No. 4,551,187 describes copper beryllium alloys having low amounts of beryllium, e.g., about 0.2 to about 0.5% by weight of beryllium. To improve the strength using these low beryllium copper beryllium alloys, the ’ 187 patent describes a finishing process of solution treating, cold working at least about 50% or at least about 70% and age hardening.

[0005] US Pub. No. 2022 / 0220597 describes a process for producing a copper-beryllium alloy product. The process comprises preparing a copper alloy having 0.15 wt % to 4.0 wt % beryllium. The alloy product comprises additional alloying elements, such as cobalt, nickel, zirconium, or combinations thereof.

[0006] Others have pursued machinable copper alloys having no beryllium. US Pub. No. 2015 / 0240340 describes a machinable precipitation hardenable copper alloy comprising between 1 and 4.1 wt. % of Ni; between 0.3 and 3.0 wt. % of Si; between 0.4 and 4.0 wt. % of Pb; no more than 0.5 wt. % of Sn; no more than 0.5 wt. % of Cr; no more than 0.5 wt. % of Zn; no more than 0.5 wt. % of Zr; no more than 0.1 wt. % of Fe; no more than 0.3 wt. % of P; and unavoidable impurities; the remainder being constituted essentially of Cu. However, this alloy has an undesirable high amount of lead, which is highly regulated.

[0007] The need exists for a copper-beryllium alloy that provides improvements in machinability while maintain high strength.SUMMARY

[0008] The present disclosure describes a machinable copper alloy, and in particular, a machinable copper-beryllium alloy. The machinable copper alloy described herein possesses high strength and excellent electrical conductivity. In one embodiment, the machinable copper alloy may be corrosion and / or galling resistant.

[0009] The copper alloys described herein may be used to produce shaped parts having high mechanical strength, and dimensional stability. The shaped part may be subjected to machining, including but are not limited to turning, drilling, milling etc.

[0010] In one aspect there is provided a machinable copper alloy that may include from 1.3 to 3.0 % by weight of beryllium; from 0.2 to 1.5 % by weight of cobalt, nickel, and iron; and from 0.15 to 0.45 % by weight of at least one “N” element comprising niobium, bismuth or combinations thereof, wherein the % by weight are based on the total weight of the copper alloy. The machinable copper alloy may include from 0 to 0.02 % by weight of at least one “Q” element comprising chromium, tin, zinc, zirconium or combinations thereof. The balance of themachinable copper alloy may copper, and preferably the machinable copper alloy may include from 94.0 to 98.3 % by weight of copper. The copper alloy may contain no more than 900 ppm of lead.

[0011] The machinable copper alloy may include from 1.3 to 3.0 % by weight of beryllium; from 0.2 to 1.5 % by weight of cobalt, nickel, and iron; and from 0.15 to 0.45 % by weight of at least one “N” element comprising niobium, wherein the % by weight are based on the total weight of the copper alloy. The machinable copper alloy may include from 0 to 0.02 % by weight, preferably from 0 to 0.005 % by weight, of at least one “Q” element comprising chromium, tin, zinc, zirconium or combinations thereof. The balance of the machinable copper alloy may copper, and preferably the machinable copper alloy may include from 94.0 to 98.3 % by weight of copper. The copper alloy may contain no more than 900 ppm of lead, e.g., preferably no more than 850 ppm of lead, and more preferably no more than 800 ppm of lead. In one embodiment, the amount of beryllium may be from 1.6 to 2.8 % by weight, and preferably the amount of beryllium may be from 1.7 to 2.2 % by weight. In one embodiment, the amount of cobalt, nickel, and iron may be from 0.25 to 1.2 % by weight, and preferably the amount of cobalt, nickel, and iron may be from 0.3 to 1.0 % by weight. The copper alloy preferably has a nickel to cobalt and iron weight ratio of greater than 1, e.g. greater than 1.5 or greater than 2. In one embodiment, the amount of the “N” element may be from 0.2 to 0.36 % by weight, and preferably the amount of the “N” element may be from 0.21 to 0.32 % by weight. The copper alloy may comprises from 0.001 to 0.5 % by weight of silicon and / or from 0.001 to 0.5 % by weight of aluminum. In one embodiment, the copper alloy may comprise from 0 to 0.25 % by weight of antimony. In one embodiment, the copper alloy may comprise from 0 to 0.01 % by weight of at least one “Z” element comprising manganese, magnesium, silver, titanium, or combinations thereof.

[0012] In one aspect there is provided a machinable copper alloy that may include from 1.3 to 3.0 % by weight of beryllium; from 0.2 to 1.5 % by weight of cobalt, nickel, and iron; and from 0.15 to 0.45 % by weight of at least one “N” element comprising bismuth, wherein the % by weight are based on the total weight of the copper alloy. The machinable copper alloy may include from 0 to 0.02 % by weight, preferably from 0 to 0.005 % by weight, of at least one “Q” element comprising chromium, tin, zinc, zirconium or combinations thereof. The balance of the machinable copper alloy may copper, and preferably the machinable copper alloy may includefrom 94.0 to 98.3 % by weight of copper. The copper alloy may contain no more than 900 ppm of lead, e.g., preferably no more than 850 ppm of lead, and more preferably no more than 800 ppm of lead. In one embodiment, the amount of beryllium may be from 1.6 to 2.8 % by weight, and preferably the amount of beryllium may be from 1.7 to 2.2 % by weight. In one embodiment, the amount of cobalt, nickel, and iron may be from 0.25 to 1.2 % by weight, and preferably the amount of cobalt, nickel, and iron may be from 0.3 to 1.0 % by weight. The copper alloy preferably has a nickel to cobalt and iron weight ratio of greater than 1, e.g. greater than 1.5 or greater than 2. In one embodiment, the amount of the “N” element, and in particular bismuth, may be from 0.2 to 0.36 % by weight, and preferably the amount of the “N” element may be from 0.21 to 0.32 % by weight. The copper alloy may comprises from 0.001 to 0.5 % by weight of silicon and / or from 0.001 to 0.5 % by weight of aluminum. In one embodiment, the copper alloy may comprise from 0 to 0.25 % by weight of antimony. In one embodiment, the copper alloy may comprise from 0 to 0.01 % by weight of at least one “Z” element comprising manganese, magnesium, silver, titanium, or combinations thereof.

[0013] In one aspect there is provided a machinable copper alloy that may comprise from 1.3 to 3.0 % by weight of beryllium; from 0.2 to 1.5 % by weight of cobalt, nickel, and iron; less than or equal 0.45 % by weight of at least one “N” element comprising niobium, bismuth or combinations thereof; up to 0.2 % by weight of tin; from 0 to 0.01 % by weight of at least one “Q” element comprising chromium, zinc, zirconium or combinations thereof; and balance copper, wherein the % by weight are based on the total weight of the copper alloy; wherein the copper alloy contains no more than 900 ppm of lead, wherein the % by weight are based on the total weight of the copper alloy. The copper alloy may contain no more than 850 ppm of lead, e.g., preferably no more than 800 ppm of lead. In one embodiment, the amount of beryllium may be from 1.6 to 2.8 % by weight, and preferably the amount of beryllium may be from 1.7 to 2.2 % by weight. In one embodiment, the amount of cobalt, nickel, and iron may be from 0.25 to 1.2 % by weight, and preferably the amount of cobalt, nickel, and iron may be from 0.3 to 1.0 % by weight. The copper alloy preferably has a nickel to cobalt and iron weight ratio of greater than 1, e g. greater than 1.5 or greater than 2. In one embodiment, the amount of the “N” element may be from 0.2 to 0.36 % by weight, and preferably the amount of the “N” element may be from 0.21 to 0.32 % by weight. The copper alloy may comprises from 0.001 to 0.5 % by weight of silicon and / or from 0.001 to 0.5 % by weight of aluminum. In one embodiment, the copper alloymay comprise from 0 to 0.25 % by weight of antimony. In one embodiment, the copper alloy may comprise from 0 to 0.01 % by weight of at least one “Z” element comprising manganese, magnesium, silver, titanium, or combinations thereof.

[0014] These and other non-limiting characteristics are more particularly described below.DETAILED DESCRIPTION

[0015] The present disclosure may be understood more readily by reference to the following detailed description of desired embodiments and the examples included therein. In the following specification and the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings.

[0016] The machinable copper alloy described herein generally comprises copper, beryllium, and at least one “N” element comprising niobium, bismuth or combinations thereof.Accordingly, in one embodiment, the copper alloy may comprise copper, beryllium, and niobium. In one embodiment, the copper alloy may comprise copper, beryllium, and bismuth. In one embodiment, the copper alloy may comprise copper, beryllium, niobium, and bismuth.

[0017] In addition to the “N” element, the copper alloy may also comprise cobalt, nickel, and iron. Preferably, the copper alloy comprises at least nickel and may comprise cobalt and / or iron. In one embodiment, the copper alloy has a nickel to cobalt and iron weight ratio that is greater than or equal to 1, e.g., greater than 1.2, greater than 1.25, greater than 1.3, or greater than 1.5. As used herein the cobalt and iron combined weight is used in this ratio. In terms of ranges, the nickel to cobalt and iron weight ratio may be from 1 to 10, e g., from 1 to 8, from 1 to 5, from 1 to 3, from 1 to 2, from 1 to 2, from 1.2 to 2, or from 1.25 to 1.75. Accordingly, in one embodiment, the copper alloy may comprise copper, beryllium, cobalt, nickel, iron, and niobium. In one embodiment, the copper alloy may comprise copper, beryllium, cobalt, nickel, iron, and bismuth. In one embodiment, the copper alloy may comprise copper, beryllium, cobalt, nickel, iron, niobium, and bismuth.

[0018] In addition to the “N” element, the copper alloy may also comprise at least one “Q” element. In one embodiment, the “Q” element may comprise one or more of chromium, tin, zinc, zirconium or combinations thereof. Preferably, “Q” element includes at least zinc and zirconium. These “Q” elements may be considered as unavoidable impurities in the copper alloys. The “Q” element may be maintained to be a minor alloying component due in part the negligible effect onstrength with the accompanying suspected loss in electrical conductivity. In one embodiment, the copper alloy does not contain any “Q” element.

[0019] In one embodiment, the copper alloy having a minor amounts or no amounts of “Q” element may also comprise aluminum as an alloy component. The amount of aluminum may exceed the amount of “Q” element.

[0020] In one embodiment, the copper alloy having a minor amounts or no amounts of “Q” element may also comprise silicon as an alloy component. Silicon when present may be in an amount comparable to aluminum.

[0021] As described herein the copper alloy contains avoidable impurities which may include “Q” element. In addition, the avoidable impurities may include antimony, lead, and “Z” element. In one embodiment, the “Z” element may comprise one or more of manganese, magnesium, silver, titanium, or combinations thereof. Typical “Z” elements may include manganese and titanium. In one embodiment, the copper alloy does not contain any antimony, lead, and / or “Z” element.

[0022] According to one aspect of the embodiments disclosed herein, the copper alloy contain multiple components. Generally copper is the primary element of the alloy as shown herein. The remaining components may be combined based on the disclosed amounts herein to achieve a copper alloy having a good machinability and high strength.

[0023] In one embodiment, the machinable copper alloy may comprise from 1.3 to 3.0 % by weight of beryllium. As used herein the % by weight are based on the total weight of the copper alloy. More preferably, the copper alloy may comprise from 1.3 to 2.8 % by weight of beryllium, e.g., from 1.6 to 2.8 % by weight, from 1.6 to 2.6 % by weight, from 1.6 to 2.5 % by weight, from 1.6 to 2.4 % by weight, from 1.6 to 2.3 % by weight, from 1.7 to 2.3 % by weight, from 1.7 to 2.2 % by weight, or from 1.8 to 2.1 % by weight. Within these ranges the minimum amount of beryllium may be at least 1.3 % by weight, e.g. at least 1.4 % by weight, at least 1.5 % by weight, at least 1.6 % by weight, at least 1.7 % by weight, at least 1.75 % by weight, or at least1.8 % by weight. To avoid substitution with other alloy components, the amount of beryllium may be greater than or equal to 1.3 % by weight. Also within these ranges of beryllium, the upper limit of beryllium may be less than or equal to 3.0 % by weight, e.g., less than or equal to2.9 % by weight, less than or equal to 2.8 % by weight, less than or equal to 2.7 % by weight, less than or equal to 2.6 % by weight, less than or equal to 2.5 % by weight, less than or equal to2.4 % by weight, less than or equal to 2.3 % by weight, less than or equal to 2.2 % by weight, or less than or equal to 2.1 % by weight.

[0024] In one embodiment, the copper alloy may comprise from 0.2 to 1.5 % by weight of cobalt, nickel, and iron. The total of weight these three components may be used for the copper alloys disclosed herein. More preferably, the copper alloy may comprise a total of cobalt, nickel, and iron in an amount from 0.2 to 1.4 % by weight, e.g., from 0.2 to 1.3 % by weight, from 0.2 to 1.2 % by weight, from 0.25 to 1.2 % by weight, from 0.3 to 1.1 % by weight, from 0.3 to 1.0 % by weight, from 0.3 to 0.9 % by weight, from 0.4 to 0.85 % by weight, or from 0.45 to 0.75 % by weight. For purposes of the present disclosure it is preferred that of these three elements, nickel may be the predominate element over cobalt and iron. Accordingly, in one embodiment, the copper alloy may comprise from 0.25 % by weight to 1.3 % by weight of nickel, e.g., 0.3 % by weight to 1.2 % by weight of nickel, 0.35 % by weight to 1.1 % by weight of nickel, or 0.4 % by weight to 1.0 % by weight of nickel. The combination of cobalt and iron in the copper alloy may be in an amount of less than or equal to 0.7 % by weight, e.g., less than or equal to 0.6 % by weight, less than or equal to 0.5 % by weight, less than or equal to 0.4 % by weight, less than or equal to 0.3 % by weight, or less than or equal to 0.25 % by weight. In terms of ranges, the combination of cobalt and iron in the copper alloy may be from 0.01 to 0.7 % by weight, e g., from 0.01 to 0.6 % by weight, or from 0.05 to 0.5 % by weight.

[0025] As a result of the inventors efforts to develop a copper alloy with good machinability, the presence of an “N” element has a positive influence. In one embodiment, the copper alloy may include from 0.15 to 0.45 % by weight of the “N” element, e.g., from 0.15 to 0.4 % by weight, from 0.2 to 0.4 % by weight, from 0.2 to 0.38 % by weight, from 0.2 to 0.36 % by weight, or from 0.25 to 0.35 % by weight. Having an “N” element within these ranges may be useful in controlling the lead amounts in the copper alloy. Within these ranges the minimum amount of an “N” element may be at least 0.15 % by weight, e.g. at least 0.16 % by weight, at least 0.2 % by weight, at least 0.21 % by weight, at least 0.22 % by weight, at least 0.23 % by weight, or at least 0.24 % by weight. The maximum amount of “N” element within the ranges may be less than or equal to 0.45 % by weight, e.g., less than 0.42 % by weight, less than 0.4 % by weight, less than 0.38 % by weight, or less than 0.36 % by weight.

[0026] Accordingly, in one embodiment, the copper alloy may comprise from 1.3 to 3.0 % by weight of beryllium, from 0.2 to 1.5 % by weight of cobalt, nickel, and iron, with a nickel tocobalt and iron weight ratio of greater than 1, from 0.15 to 0.45 % by weight of at least one “N” element, the balance being copper, e.g., greater than or equal to 95 % by weight of copper, and avoidable impurities. The unavoidable impurities may be low in the copper alloy.

[0027] Turning to other elements in the copper alloy, which may be present as alloying components or as unavoidable impurities.

[0028] The copper alloy as described herein may be a lead-free copper alloy that contains no lead or amounts of lead that may be no more than 900 ppm, based on the total weight of the copper alloy. In one embodiment, the copper alloy may contain no more than 850 ppm lead, e.g., no more than 800 ppm, no more than 750 ppm, no more than 700 ppm, no more than 650 ppm, no more than 600 ppm, or no more than 500 ppm. In terms of ranges, the lead may be from 0 to 900 ppm, e.g., from 5 to 900 ppm, from 5 to 850 ppm, from 5 to 800 ppm, from 10 to 800 ppm, from 25 to 800 ppm, from 50 to 800 ppm, from 100 to 750, from 100 to 700, or from 100 to 500.

[0029] Accordingly, in one embodiment, the copper alloy may comprise from 1.3 to 3.0 % by weight of beryllium, from 0.2 to 1.5 % by weight of cobalt, nickel, and iron, with a nickel to cobalt and iron weight ratio of greater than 1, from 0.15 to 0.45 % by weight of at least one “N” element, no more than 900 ppm of lead, the balance being copper, e.g., greater than or equal to 94 % by weight of copper, and unavoidable impurities.

[0030] In one embodiment, the copper alloy may comprise at least one “Q” element. To maintain a machinable copper alloy with high strength, the amount of the at least one “Q” element is maintained in a relatively low amount. In one embodiment, the copper alloy comprises from 0 to 0.02 % by weight of at least one “Q” element, e.g., from 0 to 0.015 % by weight, from 0 to 0.01 % by weight, from 0 to 0.009 % by weight, from 0 to 0.008 % by weight, from 0.0001 to 0.008 % by weight, 0.0001 to 0.007 % by weight. The amount of the “Q” element may be the total weight of all the “Q” elements. In one embodiment, the copper alloy may comprise no “Q” element.

[0031] In one embodiment, the amount of tin may be greater than the other “Q” elements. In one embodiment, the “Q” element is tin and the copper alloy comprises up to 0.2 % by weight of tin, e.g., up to 0.15 % by weight, up to 0.1 % by weight, or up to 0.05 % by weight. In terms of ranges, when the “Q” element is tin, the copper alloy may comprise 0 to 0.2 % by weight of tin, e.g., from 0.001 to 0.2 % by weight of tin, from 0.01 to 0.17 % by weight of tin, from 0.02 to 0.15 % by weight of tin, or from 0.05 to 0.1 % by weight of tin. When “Q” element is tin, theother “Q” elements, namely chromium, zinc, zirconium or combinations thereof may be from 0 to 0.01 % by weight as described herein.

[0032] Accordingly, in one embodiment, the copper alloy may comprise from 1.3 to 3.0 % by weight of beryllium, from 0.2 to 1.5 % by weight of cobalt, nickel, and iron, with a nickel to cobalt and iron weight ratio of greater than 1, from 0.15 to 0.45 % by weight of at least one “N” element, up to 0.2 % by weight of tin; from 0 to 0.01 % by weight of at least one “Q” element comprising chromium, zinc, zirconium or combinations thereof; and the balance being copper, e.g., greater than or equal to 94 % by weight of copper, and unavoidable impurities. The “N” element may comprise niobium, bismuth or combinations thereof.

[0033] In one embodiment, the copper alloy may comprise silicon. The amount of silicon may be from 0.001 to 0.5 % by weight, e.g., from 0.01 to 0.05 % by weight, or from 0.02 to 0.03 % by weight.

[0034] In one embodiment, the copper alloy may comprise aluminum. The amount of aluminum may be from 0.001 to 0.5 % by weight, e.g., from 0.005 to 0.04 % by weight, or from 0.02 to 0.03 % by weight.

[0035] Accordingly, in one embodiment, the copper alloy may comprise from 1.3 to 3.0 % by weight of beryllium, from 0.2 to 1.5 % by weight of cobalt, nickel, and iron, with a nickel to cobalt and iron weight ratio of greater than 1, from 0.15 to 0.45 % by weight of at least one “N” element, from 0.001 to 0.5 % by weight of silicon, from 0.001 to 0.5 % by weight of aluminum, the balance being copper, e.g., greater than or equal to 94 % by weight of copper, and unavoidable impurities.

[0036] In one embodiment, the copper alloy may comprise antimony. In particular, alloys having more than 0.01 % by weight of bismuth may contain minor amounts of antimony. The amount of antimony may be from 0 to 0.25 % by weight, e.g., from 0.001 to 0.2 % by weight, or from 0.005 to 0.05 % by weight.

[0037] In one embodiment, the copper alloy may comprise at least one “Z” element. To maintain a machinable copper alloy with high strength, the amount of the at least one “Z” element is maintained in a relatively low amount. In one embodiment, the copper alloy comprises from 0 to 0.01 % by weight of at least one “Z” element, e.g., from 0 to 0.009 % by weight, from 0 to 0.008 % by weight, from 0.0001 to 0.008 % by weight, 0.0001 to 0.007 % byweight. The amount of the “Z” element may be the total weight of all the “Z” elements. In one embodiment, the copper alloy may comprise no “Z” element.

[0038] Other elements not named may be unavoidable impurities in the copper alloy. Any other unavoidable impurity may be in amounts akin to “Q” or “Z” elements.

[0039] As described herein the copper alloy is predominately copper and the balance of the alloy may comprise copper. In terms of exemplary ranges, the copper alloy may comprise from 94.0 to 98.3 % by weight of copper, e.g., from 94.5 to 98.25 % by weight of copper, from 94.5 to 98.0 % by weight of copper, from 95.0 to 97.9 % by weight of copper, from 95.5 to 97.5 % by weight of copper. The copper alloy may have at least 94.0 % by weight or more of copper, e g., at least 94.5 % by weight or more of copper, at least 95.0 % by weight or more of copper, or at least 95.5 % by weight or more of copper.

[0040] In one exemplary embodiment, the copper alloy may comprise from 1.3 to 3.0 % by weight of beryllium, from 0.2 to 1.5 % by weight of cobalt, nickel, and iron, from 0.15 to 0.45 % by weight of at least one “N” element, from 0 to 0.01 % by weight of at least one “Q” element; from 0.001 to 0.5 % by weight of silicon, from 0.001 to 0.5 % by weight of aluminum, from 0 to 0.25 % by weight of antimony, from 0 to 0.01 % by weight of at least one “Z” element, and balance copper, preferably from 94.0 to 98.3 % by weight of copper, wherein the copper alloy contains no more than 900 ppm of lead.

[0041] In one embodiment, the copper alloy may be in the form of a plate, bar, or rod. The plate form may have a thickness from 5 mm to 250 mm, e.g., from 10 mm to 205 mm, from 10 mm to 100 mm, from 10 mm to 75 mm, or from 10 mm to 50 mm. The bar may have a thickness from 0.5 mm to 50 mm, e.g., from 0.5 to 35 mm, from 0.75 to 30 mm, or from 1 mm to 25 mm. The outer diameter of a rod may be from 0.5 mm to 50 mm, e.g., from 0.5 to 35 mm, from 0.75 to 30 mm, or from 1 mm to 25 mm. In another embodiment, the copper alloy may be in the form of a foil having a minimal thickness, e.g., less than 0.5 mm.

[0042] A process for producing a copper alloy having the composition described herein is disclosed. The process may involve a homogenized treatment or a non-homogenized treatment. A homogenized treatment may involves heating the copper alloy to create a homogeneous structure to reduce chemical or metallurgical segregation that can occur as a natural result of solidification. Diffusion of the alloy elements occurs until those elements may be evenly distributed throughout the alloy. This occurs at a temperature that is usually between 80% and95% of the solidus temperature of the alloy. Homogenization may improve plasticity, increase the consistency and the level of mechanical properties, and decreases anisotropy in the alloy. In some embodiments, the preparation of the copper alloy may include casting a billet of a copperberyllium alloy, e.g., having the composition as described herein. The preparation may further include one or more rolling operations to reduce a thickness of the billet to a desired thickness.

[0043] The casting or rolled product may be subjected to a heat treatment process. The heat treatment process may be performed above the solidus temperature of the copper-beryllium alloy for a sufficient time to obtain a single or very nearly single phase. This process may be referred to as a homogenization step. In one embodiment, the heat treatment may be performed above a temperature 300°C or more, e.g., above 305°C or more, above 310°C or more, above 315°C or more, or above 325°C or more. In terms of ranges the heat treatment may be from 300°C to 900°C, e.g., from 305°C to 850°C, from 315°C to 825°C, from 315°C to 825°C, or from 315°C to 825°C. The heat treatment may be conducted for 1 to 48 hours, e.g., from 2 to 36 hours, from 2 to 24 hours, or from 4 to 24 hours. In one embodiment, the copper alloy may be heat treated at a temperature from 315°C to 360°C for 2 to 3 hours. Following the heat treatment, the copperberyllium alloy may be quenched or otherwise rapidly cooled, as necessary.

[0044] The casting may be subject to mechanical deformation using a working step. In one embodiment, the process may use a hot working step. The hot working may permit the alloy to recrystallize during deformation. This changes the microstructure of the alloy to form finer grains that can increase the strength, ductility, and toughness of the material. There are several hot working steps which may involve hot forging, hot extrusion, hot rolling, or hot piercing (i.e., rotary piercing), or other hot working processes. The reduction ratio should be a minimum of at least 5: 1, e.g., at least 6:l or at least 10: 1. During the hot working, the casting may be reheated to a temperature of about 700 °C to about 900 °C. The reheating should be performed for about at least 10 minutes or more per one centimeter thickness of the casting. The reheating may be conducted for up to 6 hours in total.

[0045] In one embodiment, before the working step and in particular preferably a cold working step, the process may involve solution annealing. For example, the solution annealing, followed by quenching or rapid cooling, and subsequent cold working. The solution annealing may be performed by placing the copper alloy in a furnace or other similar assembly and exposing the copper alloy to an elevated temperature in the range of from 730 °C to 790 °C for atime period from 0.5 minutes to 5 minutes. In some embodiments, the solution annealing may be performed, for example, by placing the alloy in strip form on a conveyor furnace apparatus and running the alloy strip at an appropriate rate through the conveyor furnace. The quenching or rapid cooling may be achieved by air quenching, which may be performed by directing a stream of gas, such as air or an inert gas, towards the annealed copper alloy.

[0046] In some embodiments, method for preparing the machinable copper alloys described herein may involve carrying out homogenizing annealing on the copper alloy. The annealing temperature, i.e., the elevated temperature during the solution annealing operation, may range from 300 °C to 790 °C, e.g., from 310 °C to 775 °C, from 315 °C to 760 °C or from 315 °C to 750 °C. In terms of upper limits, the annealing temperature may be less than 790 °C to limit the growth of the grains into much bigger size, which may hinder the subsequent cold working. For example, the annealing temperature may be less than 790 °C, e.g., less than 780 °C, less than 770 °C, less than 760 °C, or less than 700 °C. In terms of lower limits, the annealing temperature may be at least 300 °C so as to solutionize the preliminarily cold worked alloy to allow beryllium to diffuse throughout the copper matrix. For example, the annealing temperature may be at least 300 °C, e.g., at least 305 °C, at least 315 °C, at least 325 °C, at least 350 °C, or at least 400 °C.

[0047] In some embodiments, the annealing time, i.e., the time period for which the alloy may be exposed to any of the elevated temperature described herein, may range from 0.5 minutes to 5 minutes, e.g., from 0.5 minutes to 4 minutes, from 0.5 minutes to 3 minutes, from 0.5 minutes to 2 minutes, from 0.5 minutes to 1.5 minutes, from 0.5 minutes to 1 minute, from 1 minute to 5 minutes, from 1 minute to 4 minutes, from 1 minute to 3 minutes, from 1 minute to 2 minutes, from 1 minute to 1.5 minutes, from 1.5 minutes to 5 minutes, from 1.5 minutes to 4 minutes, from 1.5 minutes to 3 minutes, from 1.5 minutes to 2 minutes, from 2 minutes to 5 minutes, from 2 minutes to 4 minutes, from 2 minutes to 3 minutes, from 3 minutes to 5 minutes, from 3 minutes to 4 minutes, or from 4 minutes to 5 minutes. In terms of upper limits, the annealing period may be less than 5 minutes, e.g., less than 4 minutes, less than 3 minutes, less than 2 minutes, less than 1.5 minutes, or less than 1 minute. In terms of lower limits, the annealing period may be at least 0.5 minutes, e.g., at least 1 minute, at least 1.5 minutes, at least 2 minutes, at least 3 minutes, or at least 4 minutes.

[0048] In some embodiment, cold working may be considered the process of mechanically altering the shape or size of the metal by plastic deformation. This can be done by rolling,drawing, pressing, spinning, extruding, or heading of the metal or alloy. Without being bound by theory, when a metal is plastically deformed, dislocations of atoms occur within the material. Particularly, the dislocations occur across or within the grains of the metal. The dislocations overlap each other and the dislocation density within the material increases. The increase in overlapping dislocations makes the movement of further dislocations more difficult. This increases the hardness and tensile strength of the resulting alloy. Cold working also improves the surface finish of the alloy. Mechanical cold working is generally performed at a temperature below the recrystallization point of the alloy, and is usually done at room temperature.

[0049] Depending on the strength characteristics desired in the final alloy product, the percentage of cold working achieved may be greater than 40%, e.g., greater than 45%, greater than 50%, greater than 55%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, or greater than 85%. In terms of ranges, the percentage of working achieved by the cold working may range from 40% to 85%, e.g., from 40% to 80%, from 40% to 75%, from 40% to 70%, from 40% to 65%, from 40% to 60%, from 40% to 50%, from 50% to85%, from 50% to 80%, from 50% to 75%, from 50% to 70%, from 50% to 65%, from 50% to60%, from 60% to 85%, from 60% to 80%, from 60% to 75%, from 60% to 70%, from 60% to65%, from 65% to 85%, from 65% to 80%, from 65% to 75%, from 65% to 70%, from 70% to85%, from 70% to 80%, from 70% to 75%, from 75% to 85%, or from 75% to 80%. In terms of upper limits, the percentage of working achieved by the cold working may be less than 85% e.g., less than 80%, less than 75%, less than 70%, or less than 65%. As will be discussed below, depending on the amount of cold working performed, the characteristics of the final copperberyllium alloy product may differ.

[0050] Upon completion of the cold working, the cold worked alloy may be heat treated to further improve at least some of the strength characteristics of the cold worked alloy. Heat treating metals or alloys may be referred to as a controlled process of heating and cooling the metals or alloys to alter their physical and mechanical properties without changing the product shape. Heat treatment is associated with increasing the strength of the material but it can also be used to alter certain manufacturability objectives such as to improve machinability, improve formability, or to restore ductility after a cold working operation. In some cases, the heat treating may comprise multiple heat treating operations. In some embodiments, the heat treatingcomprises a single heat treating operation. In some cases, the heat treating comprises strain aging.

[0051] It is noted that the heat treating is performed to further improve at least some of the strength characteristics of the cold-worked alloy by, e.g., aging or precipitation hardening. Thus, the heat treating may be performed at a relatively low temperature for a relatively short duration (discussed below), and the grain structure may be substantially unchanged by the heat treating. That is, the grain structure may remain elongated, flattened, or compressed, similar to the grain structure obtained upon completion of the cold working. This is in contrast to the heat treating by annealing, which is typically the heat treating performed in conventional processes immediately following cold working. Such annealing, which is typically performed above 525 °C for extended period of time, e.g., hours, is performed to remove any non-uniformity resulted from the cold working so as to obtain a uniform, equiaxed grain structure for increased formability at the expense of strength of the alloy products.

[0052] In some embodiments, the process may further include an aging operation to restore at least some of the strength of the annealed and quenched alloy. In some embodiments, the aging of the annealed and quenched alloy may be performed by placing the annealed and quenched alloy in a furnace or other similar assembly and exposing the annealed and quenched alloy to an elevated temperature in the range from 240 °C to 320 °C for a time period of from 1 hour to 5 hours. During the aging operation, beryl lium-containing compound(s) may be formed as interstitial components or precipitates in the copper matrix to strengthen the alloy.

[0053] In some embodiments, the aging temperature, i.e., the elevated temperature to which the annealed and quenched alloy may be exposed during the aging operation, may range from 240 °C to 450 °C, e.g., from 245 °C to 425 °C, from 245 °C to 400 °C, from 245 °C to 375 °C, from 245 °C to 350 °C. In terms of upper limits, the aging temperature may be less than 450 °C, e.g., less than 425 °C, less than 400 °C, less than 390 °C, less than 375 °C, less than 360 °C, less than 350 °C, or less than 300 °C. In terms of lower limits, the aging temperature may be at least 240 °C, e.g., at least 245 °C, at least 250 °C, at least 255 °C, or at least 260 °C.

[0054] In some embodiments, the aging time, i.e., the time period for which the annealed and quenched alloy may be exposed to any of the elevated temperature described above, may range from 1 minute to 240 minutes, e.g., from 1 minute to 120 minutes, from 1 minute to 90 minutes, from 1 minute to 60 minutes, from 1 minute to 30 minutes, from 1 minute to 15 minutes, from 1minute to 10 minutes. In terms of upper limits, the aging time may preferably be less than 240 minutes, e.g., less than 180 minutes, less than 120 minutes, less than 90 minutes, less than 45 minutes, less than 30 minutes, less than 25 minutes, or less than 20 minutes. Although not preferred, longer aging times may be used. In terms of lower limits, the aging time may be at least 1 minute, e.g., at least 2 minutes, at least 2.5 minutes, at least 3 minutes, at least 3.5 minutes, or at least 4 minutes.

[0055] The copper-beryllium alloy product may demonstrate improved fatigue strength, as measured along the direction of the cold working, at various amounts of testing cycles.

[0056] In terms of tensile strength, the copper alloy may demonstrate an ultimate tensile strength (after heat treatment) ranging from 1150 MPa to 1800 MPa, e.g., from 1200 MPa to 1750 MPa, from 1275 MPa to 1575 MPa, from 1275 MPa to 1500 MPa, 1275 MPa to 1450 MPa, from 1300 MPa to 1440 MPa. In terms of lower limits, the copper alloy may demonstrate an ultimate tensile strength of at least 1150 MPa or more, e.g., at least 1175 MPa, at least 1200 MPa, at least 1250 MPa, at least 1275 MPa, at least 1300 MPa or at least 1325 MPa. In terms of upper limits, the copper alloy may demonstrate an ultimate tensile strength of less than or equal to 1800 MPa, e.g., less than 1775 MPa, less than 1750 MPa, less than 1725 MPa, less than 1700 MPa, less than 1600 MPa, less than 1550 MPa, or less than 1450 MPa.

[0057] In terms of yield strength, the copper alloy may demonstrate a 0.2% offset yield strength (after heat treatment) ranging from 800 MPa to 1725 MPa, e.g., from 825 MPa to 1725 MPa, from 950 MPa to 1550 MPa, from 1100 MPa to 1450 MPa, from 1100 MPa to 1400 MPa, 1125 MPa to 1400 MPa, or from 1250 MPa to 1400 MPa. In terms of lower limits, the copper alloy may demonstrate a 0.2% offset yield strength of at least 800 MPa or more, e.g., at least 900 MPa, at least 1000 MPa, at least 1150 MPa, at least 1200 MPa, or at least 1250 MPa. In terms of upper limits, the copper alloy may demonstrate a 0.2% offset yield strength of less than or equal to 1700 MPa, e.g., less than 1650 MPa, less than 1600 MPa, less than 1550 MPa, less than 1500 MPa, or less than 1450 MPa.

[0058] The 0.2% offset yield strength and ultimate tensile strength may be measured according to ASTM E8.

[0059] In terms of elongation, the copper alloy may demonstrate an elongation ranging from 2% to 35%, e.g., from 5% to 35%, from 6% to 30%, from 8% to 30%, from 9% to 25% or from9% to 15%. In some embodiments, the elongation may range from 2% to 10%, e.g., from 2% to 9%, or from 2% to 5%. The % elongation may be measured according to ASTM E3.

[0060] In terms of machinability, the copper alloy may demonstrate one or more improvements in machining parameters for copper and copper alloys. In one embodiment, copper alloys described herein may have improved machinability for the manufacturing of precision parts with tightly tolerances. Mechanical machining may include but is not limited to sawing, drilling, tapping, boring, milling, turning, grinding, burnishing, reaming, electrical discharge machining, etc. Mechanical machining may be used to obtain the final shape of the product made from the copper alloys disclosed herein. In one embodiment, product produced by the copper alloy are characterized by excellent machinability, which may be greater than that of other copper alloys, including copper-nickel-tin alloys and copper-beryllium.

[0061] The machinable copper alloy may be used to manufacture aerospace bushings, automotive connectors, computer processor socket contacts, and other electrical connectors such as sockets and pins.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0063] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0064] As used in the specification and in the claims, the term “comprising” may include the embodiments “consisting of’ and “consisting essentially of.” The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases that require the presence of the named ingredients / steps and permit the presence of other ingredients / steps. However, such description should be construed as also describing compositions or processes as “consisting of’ and “consisting essentially of’ the enumerated ingredients / steps, which allows the presence of onlythe named ingredients / steps, along with any impurities that might result therefrom, and excludes other ingredients / steps.

[0065] Numerical values in the specification and claims of this application, as they relate to polymers or polymer compositions, reflect average values for a composition that may contain individual polymers of different characteristics. The numerical values disclosed herein should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0066] All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of “from 2 microns to 5 microns” is inclusive of the endpoints, 2 microns and 5 microns, and all the intermediate values). The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value; they are sufficiently imprecise to include values approximating these ranges and / or values.

[0067] As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially,” may not be limited to the precise value specified, in some cases. The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1.

[0068] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is explicitly contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are explicitly contemplated.

[0069] The present disclosure has been described with reference to exemplary embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the present disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof. In some embodiments, any or some of the steps or componentsdisclosed herein may be considered optional. In some cases, any or some of the aforementioned items in this description may be expressly excluded, e.g., via claim language. For example claim language may be modified to recite additional process steps.

[0070] The invention is explained in greater detail with reference to the examples below.Examples

[0071] Copper alloys were casted into billets of equal format. The copper alloys did not contain any element “Z”. The composition of the alloys is shown in Table 1.

[0072] The alloys were subsequently processed. The combinations of properties, including 0.2% offset yield strength (YS), ultimate tensile strength (UTS) and elongation, attained are shown in Table 2 below. Table 2 also indicates an improvement in yield strength and ultimate tensile strength after a heat treatment at 315 °C for 2 hours.

[0073] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference. In addition, it should be understood that aspects of the invention and portions of various embodiments and various features recited below and / or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will be appreciated by one of skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit.

Claims

What is Claimed is:

1. A machinable copper alloy comprising: from 1.3 to 3.0 % by weight of beryllium; from 0.2 to 1.5 % by weight of cobalt, nickel, and iron; from 0.15 to 0.45 % by weight of at least one “N” element comprising niobium, bismuth or combinations thereof; from 0 to 0.01 % by weight of at least one “Q” element comprising chromium, tin, zinc, zirconium or combinations thereof; and balance copper, wherein the % by weight are based on the total weight of the copper alloy; wherein the copper alloy contains no more than 900 ppm of lead.

2. The copper alloy of claim 1, wherein the amount of beryllium is from 1.6 to 2.8 % by weight, and preferably the amount of beryllium is from 1.7 to 2.2 % by weight.

3. The copper alloy of any one of claims 1 or 2, wherein the amount of cobalt, nickel, and iron is from 0.25 to 1.2 % by weight, and preferably the amount of cobalt, nickel, and iron is from 0.3 to 1.0 % by weight.

4. The copper alloy of any one of claims 1-3, wherein the amount of the “N” element is from 0.2 to 0.36 % by weight, and preferably the amount of the “N” element is from 0.21 to 0.32 % by weight.

5. The copper alloy of any one of claims 1-4, wherein the copper alloy comprises from 0.001 to 0.5 % by weight of silicon.

6. The copper alloy of any one of claims 1-5, wherein the copper alloy comprises from 0.001 to 0.5 % by weight of aluminum.

7. The copper alloy of any one of claims 1-6, wherein the copper alloy comprises from 0 to 0.25 % by weight of antimony.

8. The copper alloy of any one of claims 1-7, wherein the amount of the “Q” element is from 0 to 0.005 % by weight.

9. The copper alloy of any one of claims 1-8, wherein the copper alloy contains no more than 850 ppm of lead.

10. The copper alloy of any one of claims 1-9, wherein the copper alloy contains no more than 800 ppm of lead.

11. The copper alloy of any one of claims 1-10, wherein the copper alloy has a nickel to cobalt and iron weight ratio of greater than 1.

12. The copper alloy of claim 11, wherein the nickel to cobalt and iron weight ratio is greater than 1.5.

13. The copper alloy of claim 11, wherein the nickel to cobalt and iron weight ratio is greater than 2.

14. The copper alloy of any one of claims 1-13, wherein the copper alloy comprises from 0 to 0.01 % by weight of at least one “Z” element comprising manganese, magnesium, silver, titanium, or combinations thereof.

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