Resistor and its manufacturing method

Abstract

To provide a resistor having adequate hardness, adequate volume resistivity and adequate resistance temperature coefficient, and a method for manufacturing the same.SOLUTION: A resistor is composed of a Ni-based alloy. The Ni-based alloy contains 15.0≤Cr≤25.0 mass%, 1.0≤Al≤4.0 mass%, 1.0≤Cu≤3.0 mass%, 0≤Si≤1.5 mass%, 0≤Mn≤1.5 mass%, and the balance Ni with inevitable impurities. The resistor has Vickers hardness at 20°C of 160 Hv or more and 230 Hv or less, volume resistivity at 20°C of 125 μΩ cm or more and 150 μΩ cm or less, and a resistance temperature coefficient at 20 to 155°C of -50 ppm or more and 10 ppm / °C or less. The resistor is obtained by subjecting a cold molding to heat treatment under a prescribed condition.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resistor and a manufacturing method thereof, and more particularly to a resistor having appropriate hardness, appropriate volume resistivity, and appropriate temperature coefficient of resistance, and a manufacturing method thereof. [Background technology]

[0002] In recent years, with the development and improvement of performance in power supplies and electric vehicles, there is an increasing demand for precision resistor materials, especially resistor materials with high volume resistivity and low temperature coefficient of resistance. Furthermore, with the spread of SiC power devices, which have a higher operating temperature than conventional Si power devices, resistor materials are also required to have stable characteristics at temperatures above 150°C. For this reason, various proposals have been made for such resistor materials.

[0003] For example, Patent Document 1 states: (a) melting an alloy containing predetermined amounts of Cr, Al, Mn, and Si, with the balance being Ni; (b) The ingot is processed into a desired shape. (c) The workpiece is solution-treated at 900°C for 30 minutes. The precision electrical resistance alloy obtained by the above process is disclosed. The document describes that by adding a certain amount of Si to Ni-Cr-Al alloys for precision electrical resistance, the aging treatment that was previously required can be omitted, and the mechanical and electrical properties can be adjusted by solution treatment alone.

[0004] In Patent Document 2, (a) Ni-25 mass% Cr-3 mass% Cu-3 mass% Al was melted, (b) The ingot is subjected to homogenization heat treatment and cold working, (c) Heat the cold-worked material at 1000°C for 1 hour, then cool it in the furnace at 300°C / Hr. A precision resistance alloy obtained by The same document reports that, using this method, the specific electrical resistivity was 114 μΩ cm (20°C) and the temperature coefficient of specific electrical resistivity (TCR) was +90×10 -6 It is also described that a precision resistance alloy having a melting point of 0 to 50°C can be obtained.

[0005] Patent Document 3 discloses a resistance wire made of Ni-19 mass % Cr-3 mass % Al-1 mass % Mn. The document describes that when a specified amount of Mn is added to a Ni-Cr precision resistance wire, the alloy resistivity increases and the temperature coefficient decreases.

[0006] Patent Document 4 discloses a Ni alloy for precision resistors that is composed of Ni-19 mass% Cr-3 mass% Mn-3 mass% Al-1 mass% Si. The document describes that the addition of a certain amount of Si to a Ni-Mn-Cr-Al alloy increases the specific electrical resistivity without increasing the temperature coefficient of resistance.

[0007] Patent Document 5 discloses an electric resistance alloy made of Ni-4 mass % Al-2 mass % Cu-20 mass % Cr. The article states that this electrical resistance alloy has a resistance of about 900 ohms per circular mil-foot at 20°C and a temperature coefficient of resistance of 7 x 10 -6 The points are stated as ohms / ohms / °C.

[0008] Furthermore, Patent Document 6 discloses an electric resistance alloy consisting of Ni-20 mass % Cr-1.5 mass % Cu-1.5 mass % Al. The article states that this electrical resistance alloy has a resistance of about 668 ohms (CMF) and a temperature coefficient of resistance of 33×10 -6 The point is stated to be ohms.

[0009] Conventionally, metal thin-film resistors made of Cu-Mn alloys with a small temperature coefficient of resistance have been used as precision resistance materials. However, conventional Cu-Mn alloys have a problem in that they have a low volume resistivity. On the other hand, Ni-Cr-Al alloys generally have a small temperature coefficient of resistance and a large volume resistivity, but when the manufacturing conditions of conventional Ni-Cr-Al alloys are inappropriate, the temperature coefficient of resistance may become large or the hardness may become excessively high, resulting in poor workability. Furthermore, there has been no prior art example in which a resistor having appropriate hardness, appropriate volume resistivity, and appropriate temperature coefficient of resistance has been proposed. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 44-028783 [Patent Document 2] Japanese Patent Application Publication No. 04-052243 [Patent Document 3] Special Publication No. 35-008458 [Patent Document 4] Special Publication No. 43-017499 [Patent Document 5] U.S. Patent No. 2,293,878 [Patent Document 6] U.S. Patent No. 2,638,425 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a resistor having appropriate hardness, appropriate volume resistivity, and appropriate temperature coefficient of resistance. Another object of the present invention is to provide a method for manufacturing such a resistor. [Means for solving the problem]

[0012] In order to solve the above problems, a resistor according to the present invention has the following configuration. (1) The resistor is made of a Ni-based alloy, The Ni-based alloy is 15.0≦Cr≦25.0mass%, 1.0≦Al≦4.0mass%, 1.0≦Cu≦3.0mass%, 0≦Si≦1.5mass%, and 0≦Mn≦1.5mass% The remainder consists of Ni and unavoidable impurities. (2) The resistor is The Vickers hardness at 20°C is 160Hv or more and 230Hv or less, The volume resistivity at 20°C is 125 μΩ cm or more and 150 μΩ cm or less, Temperature coefficient of resistance is -50 at 20 to 155°C ppm / ℃ or more and 10 ppm / ℃ or less.

[0013] The method for producing a resistor according to the present invention includes the steps of: The raw materials are melted and cast, 15.0≦Cr≦25.0mass%, 1.0≦Al≦4.0mass%, 1.0≦Cu≦3.0mass%, 0≦Si≦1.5mass%, and 0≦Mn≦1.5mass% a melting and casting process for obtaining an ingot comprising the above-mentioned metal, the balance being Ni and unavoidable impurities; a homogenization heat treatment step of performing a homogenization heat treatment on the ingot to obtain a heat-treated body; a hot working step of hot working the heat-treated body to obtain a hot-formed body; a cold working step of performing cold working on the hot-formed body to obtain a cold-formed body; a heat treatment step of performing a heat treatment on the cold-formed body to remove distortion and control the amount of γ' phase precipitation and the amount of short-range ordered phase formed, thereby obtaining a resistor according to the present invention; It is equipped with:

[0014] The heat treatment step includes: A solution treatment process in which the cold-formed body is held at a heating temperature of 800°C to 1200°C for 30 seconds to 3 hours, and then cooled in the temperature range from the heating temperature to 400°C at an average cooling rate capable of obtaining the resistor according to the present invention. The above may also be provided.

[0015] Alternatively, the heat treatment step includes: a solution treatment process in which the cold-formed body is held at a heating temperature of 800° C. or more and 1200° C. or less for 30 seconds or more and 3 hours or less, and then cooled at an average cooling rate exceeding air cooling in a temperature range from the heating temperature to 400° C. to obtain a solution-treated body; an annealing step of holding the solution-treated body at a heating temperature of 200° C. or higher and 700° C. or lower for 30 seconds or longer and 5 hours or shorter to obtain a resistor according to the present invention; The above may also be provided. Effect of the Invention

[0016] The hardness, volume resistivity, and temperature coefficient of resistance (TCR) of the resistor according to the present invention depend not only on the composition of the resistor but also on the amount of γ' phase (Ni3Al phase) precipitated in the resistor and the amount of short-range ordered phase (SRO) formed. In addition, both the amount of γ' phase precipitated and the amount of SRO formed depend on the heat treatment conditions. Therefore, by optimizing the heat treatment conditions in addition to optimizing the composition, a resistor having appropriate hardness, appropriate volume resistivity, and appropriate temperature coefficient of resistance can be obtained. [Brief description of the drawings]

[0017] [Figure 1] 4 shows the hardness of resistors obtained in Examples 1 and 6 and Comparative Examples 1 to 4. [Diagram 2] 1 shows the volume resistivities of the resistors obtained in Examples 1 and 6 and Comparative Examples 1 to 4. [Diagram 3] 4 shows the temperature coefficients of resistance of resistors obtained in Examples 1 and 6 and Comparative Examples 1 to 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] An embodiment of the present invention will be described in detail below. [1. Ni-based alloy] [1.1. Main components] The resistor according to the present invention is made of a Ni-based alloy. The Ni-based alloy contains the following elements, with the balance being Ni and unavoidable impurities. The types of the added elements, their component ranges, and the reasons for their limitations are as follows:

[0019] (1) 15.0≦Cr≦25.0mass%: Cr dissolves in Ni and has the effect of increasing the volume resistivity and decreasing the absolute value of the temperature coefficient of resistance. In addition, by forming a short-range ordered phase, it is possible to further increase the volume resistivity and further decrease the absolute value of the temperature coefficient of resistance. In order to obtain such effects, the Cr content must be 15.0 mass% or more. The Cr content is preferably 18.0 mass% or more. On the other hand, if the Cr content is excessive, the short-range ordered phase may become completely ordered to form the Ni2Cr phase. If the Ni2Cr phase is formed, the effect of increasing the volume resistivity and decreasing the absolute value of the temperature coefficient of resistivity due to the formation of the short-range ordered phase cannot be obtained. Therefore, the Cr content must be 25.0 mass% or less. The Cr content is preferably 22.0 mass% or less.

[0020] (2) 1.0≦Al≦4.0mass%: Al dissolves in Ni to increase the volume resistivity and to reduce the absolute value of the temperature coefficient of resistance. To obtain these effects, the amount of Al must be 1.0 mass% or more. The amount of Al is preferably 2.0 mass% or more. On the other hand, if the Al content is excessive, the γ' phase (Ni3Al phase) is easily formed. If an excessive amount of the γ' phase is formed, the hardness increases excessively, and workability may be impaired. Therefore, the Al content must be 4.0 mass% or less. The Al content is preferably 3.0 mass% or less.

[0021] (3) 1.0≦Cu≦3.0mass%: Like Al, Cu dissolves in Ni to increase the volume resistivity and to reduce the absolute value of the temperature coefficient of resistance. To obtain such effects, the Cu content must be 1.0 mass% or more. The Cu content is preferably 1.5 mass% or more. On the other hand, if the Cu content is excessive, the hot workability may be deteriorated. Therefore, the Cu content must be 3.0 mass% or less. The Cu content is preferably 2.5 mass% or less.

[0022] (4) 0≦Si≦1.5mass%: Silicon is an element that mainly acts as a deoxidizer during melting and refining, and can be contained as necessary. Silicon also contributes to an increase in the volume resistivity. The amount of silicon is preferably 0.5 mass% or more. On the other hand, if the Si content is excessive, toughness and hot workability may decrease. Therefore, the Si content must be 1.5 mass% or less. The Si content is preferably 1.2 mass% or less.

[0023] (5) 0≦Mn≦1.5mass%: Mn, like Si, is an element that mainly acts as a deoxidizer during melting and refining, and can be contained as necessary. Mn also contributes to an increase in volume resistivity. The Mn content is preferably 0.5 mass% or more. On the other hand, if the Mn content is excessive, the hot workability may be deteriorated. Therefore, the Mn content must be 1.5 mass% or less. The Mn content is preferably 1.2 mass% or less.

[0024] [1.2. Inevitable impurities] (6) C≦0.01 mass%: (7)P≦0.01mass%: (8)S≦0.01mass%: (9) Mo≦0.1 mass%: (10)W≦0.1mass%: (11)V≦0.1mass%: (12) Ti≦0.1mass%: (13)Fe≦0.5mass%: (14)O≦0.01mass%: (15)N≦0.01mass%:

[0025] The Ni-based alloy according to the present invention may contain unavoidable impurities. Examples of the unavoidable impurities include C, P, S, Mo, W, V, Ti, Fe, O, and N. The lower the content of these elements, the better. In order to suppress the deterioration of the electrical properties of the Ni-based alloy, it is preferable that the content of these elements is limited to the above content.

[0026] [2. Resistor] The resistor according to the present invention comprises: Made of Ni-based alloy, The Vickers hardness at 20°C is 160Hv or more and 230Hv or less, The volume resistivity at 20°C is 125 μΩ cm or more and 150 μΩ cm or less, Temperature coefficient of resistance is -50 at 20 to 155°C ppm / ℃ or more and 10 ppm / ℃ or less.

[0027] [2.1. Ni-based alloy] The resistor according to the present invention is made of a Ni-based alloy. Details of the Ni-based alloy are as described above, so a detailed description will be omitted.

[0028] [2.2. Characteristics] [2.2.1. Vickers hardness] The hardness of the resistor according to the present invention depends mainly on the amount of γ' phase precipitation. The amount of γ' phase precipitation depends mainly on the composition of the resistor and the heat treatment conditions (particularly the cooling rate during solution treatment). By optimizing the components and heat treatment conditions, a resistor having a Vickers hardness of 160HV to 230Hv at 20°C can be obtained.

[0029] [2.2.2. Volume resistivity] The volume resistivity of the resistor according to the present invention depends mainly on the amount of γ' phase precipitation and the amount of short range ordered phase (SRO) formed. The amount of γ' phase precipitation and the amount of SRO formed also depend on the composition of the resistor and the heat treatment conditions (particularly the cooling rate during solution treatment and the annealing conditions). By optimizing the components and heat treatment conditions, a resistor having a volume resistivity of 125 μΩ cm to 150 μΩ cm at 20°C can be obtained.

[0030] [2.2.3. Temperature coefficient of resistance] "Temperature coefficient of resistance (TCR)" refers to the value expressed by the following formula (1). Temperature coefficient of resistance (ppm / ℃) = {(RR a ) / R a}×10 6 / (TT a ) …(1) however, R a is the resistance at the reference temperature, R is the resistance at any temperature. T a is the reference temperature (20°C in this invention), T is an arbitrary temperature (155° C. in this invention).

[0031] The resistor according to the present invention is obtained by performing an appropriate heat treatment on a Ni-based alloy with optimized components. Therefore, the resistor according to the present invention has a smaller absolute value of the temperature coefficient of resistance and a higher thermal stability of the temperature coefficient of resistance than conventional resistors. By optimizing the components and heat treatment conditions, a resistor with a temperature coefficient of resistance of -50 ppm / °C or more and 10 ppm / °C or less at 20 to 155°C can be obtained.

[0032] 2.2.4. Thickness The resistor according to the present invention has a high volume resistivity, a small absolute value of the temperature coefficient of resistance, and is easy to process. Therefore, it can be easily processed into a thin ribbon shape. By optimizing the manufacturing conditions, a resistor with a thickness of 3 mm or less can be obtained.

[0033] [3. Resistor manufacturing method] The method for producing a resistor according to the present invention includes the steps of: The raw materials are melted and cast, 15.0≦Cr≦25.0mass%, 1.0≦Al≦4.0mass%, 1.0≦Cu≦3.0mass%, 0≦Si≦1.5mass%, and 0≦Mn≦1.5mass% a melting and casting process for obtaining an ingot comprising the above-mentioned metal, the balance being Ni and unavoidable impurities; a homogenization heat treatment step of performing a homogenization heat treatment on the ingot to obtain a heat-treated body; a hot working step of hot working the heat-treated body to obtain a hot-formed body; a cold working step of performing cold working on the hot-formed body to obtain a cold-formed body; a heat treatment step of performing a heat treatment on the cold-formed body to remove distortion and control the amount of γ' phase precipitation and the amount of short-range ordered phase formed, thereby obtaining a resistor according to the present invention; It is equipped with:

[0034] [3.1. Melting and casting process] First, raw materials blended to obtain the resistor according to the present invention are melted and cast to obtain an ingot (melting and casting process). The method and conditions for melting and casting are not particularly limited, and well-known methods can be used.

[0035] [3.2. Homogenization heat treatment process] Next, the ingot is subjected to a homogenization heat treatment to obtain a heat-treated body (homogenization heat treatment step). The resistor according to the present invention uses a Ni-based alloy containing a large amount of Cr, and therefore elements are likely to segregate in the as-cast state. The homogenization heat treatment is performed to remove such segregation of elements.

[0036] If the homogenization heat treatment temperature is too low, segregation of elements cannot be sufficiently removed. Therefore, the heat treatment temperature is preferably 1000° C. or higher. The heat treatment temperature is preferably 1100° C. or higher, and more preferably 1200° C. or higher. On the other hand, if the heat treatment temperature is too high, oxidation may progress rapidly and the oxide layer may need to be removed. Therefore, the heat treatment temperature is preferably 1250° C. or less.

[0037] If the homogenization heat treatment time is too short, segregation of elements cannot be sufficiently removed. Therefore, the heat treatment time is preferably 4 hours or more. The heat treatment time is preferably 8 hours or more, and more preferably 16 hours or more. On the other hand, if the heat treatment time is too long, it may be necessary to remove the oxide layer, so the heat treatment time is preferably 24 hours or less.

[0038] [3.3. Hot working process] Next, the heat-treated body is subjected to hot working to obtain a hot-formed body (hot working step). The hot working is performed to homogenize the structure and process it into a rough shape. The method and conditions of the hot working are not particularly limited as long as the structure can be homogenized and the shape can be processed into a rough shape. In addition, a solution treatment may be performed after the hot working and before the cold working. The solution treatment before the cold working has the advantage that the material that has been work-hardened by the hot working is softened, making it easier to perform the cold working.

[0039] [3.4. Cold working process] Next, the hot-formed body is subjected to cold working to obtain a cold-formed body (cold working step). Usually, high thickness accuracy cannot be obtained by hot working alone. Cold working is performed to process the body into a final thickness dimension. The method and conditions of cold working are not particularly limited as long as the desired dimensional accuracy can be obtained.

[0040] [3.5. Heat treatment process] Next, the cold-formed body is subjected to a heat treatment for removing strain and controlling the amount of γ' phase precipitated and the amount of short-range ordered phase formed (heat treatment step), thereby obtaining a resistor according to the present invention.

[0041] In order to obtain a high volume resistivity and a stable temperature coefficient of resistance, it is necessary to generate a short-range ordered phase in the Ni-based alloy. In the cooling process after hot working, such a short-range ordered phase may be generated. However, since the short-range ordered phase is destroyed by cold working, the volume resistivity is small and the absolute value of the temperature coefficient of resistance is large in the cold-worked state. In addition, if the cooling rate during heat treatment after cold working is fast and the generation of the short-range ordered phase is insufficient, the volume resistivity is small and the absolute value of the temperature coefficient of resistance is large. Furthermore, if the strain is not sufficiently removed by heat treatment after cold working, the strain is gradually relaxed in the usage environment, and the volume resistivity and the temperature coefficient of resistance change.

[0042] Therefore, it is necessary to sufficiently re-form the short-range ordered phase that has disappeared due to cold working, thereby increasing the volume resistivity and decreasing the absolute value of the temperature coefficient of resistivity, and at the same time, it is necessary to sufficiently remove the residual strain. However, it is preferable to carry out the heat treatment under conditions that do not cause excessive precipitation of the γ' phase, since if the heat treatment is carried out under conditions that cause excessive precipitation of the γ' phase, not only will the volume resistivity decrease and the absolute value of the temperature coefficient of resistance increase, but the hardness of the resistor may also become excessively high. Specific examples of the heat treatment method include the following.

[0043] [3.5.1. First method] The heat treatment step includes: A solution treatment process in which the cold-formed body is held at a heating temperature of 800°C to 1200°C for 30 seconds to 3 hours, and then cooled in the temperature range from the heating temperature to 400°C at an average cooling rate capable of obtaining the resistor according to the present invention. The above may also be provided.

[0044] Here, "solution treatment" means (a) The cold-formed body is held at a relatively high solution treatment temperature for a relatively short period of time to form a solid solution in which elements are uniformly dissolved macroscopically and the ordered phase is eliminated; (b) The solid solution is then cooled from the solution treatment temperature at a predetermined average cooling rate to form a short-range ordered phase during the cooling process. This refers to processing. "Average cooling rate" refers to the temperature difference (ΔT) between the heating temperature and 400°C divided by the time (t) required for cooling (= ΔT / t).

[0045] If the temperature of the solution treatment is too low, the removal of distortion and the solid solution of elements will be insufficient. Therefore, the treatment temperature is preferably 800° C. or higher, and more preferably 1000° C. or higher. On the other hand, if the temperature of the solution treatment is too high, the crystal grains grow too rapidly, and the material strength may decrease. Therefore, the treatment temperature is preferably 1200° C. or less. The treatment temperature is preferably 1100° C. or less.

[0046] If the solution treatment time is too short, the removal of distortion and the solid solution of elements will be insufficient. Therefore, the heat treatment time is preferably 30 seconds or more. The heat treatment time is preferably 60 seconds or more, and more preferably 90 seconds or more. On the other hand, if the solution treatment time is too long, crystal grains may grow and the material strength may decrease, so the heat treatment time is preferably 3 hours or less.

[0047] If the average cooling rate is too slow, the γ' phase (Ni3Al phase) precipitates during cooling, increasing hardness. The precipitation of the γ' phase also leads to a decrease in volume resistivity and an increase in the absolute value of the temperature coefficient of resistance. On the other hand, if the average cooling rate is too fast, the formation of the short-range ordered phase becomes insufficient, a sufficiently large volume resistivity cannot be obtained, and the absolute value of the temperature coefficient of resistance also becomes large. Therefore, when only the solution treatment is performed, it is preferable to select an optimal value for the average cooling rate so that the resistor according to the present invention can be obtained.

[0048] The average cooling rate during solution treatment depends not only on the cooling method but also on the shape of the cold-formed body. For example, when the thickness of the cold-formed body is 2 mm or less, the precipitation of the γ' phase may be suppressed by simply heating the cold-formed body to the solution treatment temperature and then air-cooling it. On the other hand, when the thickness of the cold-formed body exceeds 2 mm, if the cold-formed body is heated to the solution treatment temperature and then air-cooled, an excess of γ' phase may precipitate during the cooling process, resulting in an increase in hardness. In such a case, it is preferable to perform cooling using a cooling method that provides an average cooling rate that exceeds that of air cooling. Examples of such cooling methods include gas quenching.

[0049] However, when water cooling is performed, the formation of the short-range ordered phase becomes insufficient. As a result, the volume resistivity may be excessively decreased and the absolute value of the temperature coefficient of resistivity may be increased. Therefore, the average cooling rate is preferably greater than air cooling and less than water cooling. An example of an average cooling rate greater than air cooling is 100°C / min or more. An example of an average cooling rate less than water cooling is less than 60,000°C / min. By using the above-mentioned gas quenching, it is possible to achieve an average cooling rate of 100°C / min or more and 10,000°C / min or less.

[0050] [3.5.1. Second Method] The heat treatment process is a solution treatment process in which the cold-formed body is held at a heating temperature of 800°C or more and 1200°C or less for 30 seconds or more and 3 hours or less, and then cooled at a cooling rate exceeding air cooling in a temperature range from the heating temperature to 400°C to obtain a solution-treated body; an annealing step of holding the solution-treated body at a heating temperature of 200° C. or higher and 700° C. or lower for 30 seconds or longer and 5 hours or shorter to obtain a resistor according to the present invention; The above may also be provided. That is, the heat treatment step may be one that can obtain the resistor according to the present invention by solution treatment and annealing.

[0051] [A. Solution treatment] As described above, when the cold-formed body is heated to the solution treatment temperature and then water-cooled, the volume resistivity may be excessively decreased and the absolute value of the temperature coefficient of resistivity may be increased. However, in the second method, annealing is performed after the solution treatment. When the annealing conditions are optimized, an appropriate short-range ordered phase is formed, the volume resistivity increases, and the absolute value of the temperature coefficient of resistivity decreases. Therefore, in the second method, the cooling method during the solution treatment may be water-cooling. Other points regarding the solution treatment are the same as those in the first method, so the explanation will be omitted.

[0052] [B. Annealing treatment] The term "annealing treatment" refers to a process in which a cold-formed body is solution-treated, and then the solution-treated body is held at a predetermined annealing temperature for a relatively long period of time, thereby simultaneously removing the strain introduced during the solution treatment and forming a short-range ordered phase.

[0053] If the annealing temperature is too low, the short-range ordered phase cannot be sufficiently formed within a practical annealing time, so the annealing temperature is preferably 200° C. or higher. On the other hand, if the annealing temperature is too high, the γ' phase (Ni3Al phase) precipitates, ordering progresses excessively, or the ordered phase disappears due to a part or all of the metal structure becoming a solid solution state. As a result, the volume resistivity may decrease or the absolute value of the resistance change rate may increase. Therefore, the annealing temperature is preferably 700°C or less.

[0054] If the annealing time is too short, the formation of the short-range ordered phase becomes insufficient. Therefore, the annealing time is preferably 30 seconds or more. The annealing time is preferably 60 seconds or more, and more preferably 90 seconds or more. On the other hand, if the annealing time is too long, the productivity is reduced. Therefore, the annealing time is preferably 5 hours or less, more preferably 4 hours or less, and further preferably 3 hours or less.

[0055] [4. Effect] The hardness, volume resistivity, and temperature coefficient of resistance (TCR) of the resistor according to the present invention depend not only on the composition of the resistor but also on the amount of γ' phase (Ni3Al phase) precipitated in the resistor and the amount of short-range ordered phase (SRO) formed. In addition, both the amount of γ' phase precipitated and the amount of SRO formed depend on the heat treatment conditions. Therefore, by optimizing the heat treatment conditions in addition to optimizing the composition, a resistor having appropriate hardness, appropriate volume resistivity, and appropriate temperature coefficient of resistance can be obtained.

[0056] Specifically, the slower the cooling rate during solution treatment, the higher the hardness of the resistor, which is believed to be because the amount of γ' phase precipitated increases as the cooling rate slows. In addition, the slower the cooling rate during the solution treatment, the higher the volume resistivity and the lower the absolute value of the TCR, which is believed to be because the slower the cooling rate, the greater the amount of SRO formed. However, if the cooling rate during the solution treatment is too slow, the volume resistivity may decrease and the absolute value of the TCR may increase. This is believed to be because an excessively slow cooling rate causes excessive precipitation of the γ' phase during the cooling process.

[0057] When annealing is performed after solution treatment, the hardness of the resistor may increase if the annealing temperature is 500° C. or higher. This is believed to be due to the precipitation of the γ' phase during annealing. Furthermore, when annealing is performed after the solution treatment, the higher the annealing temperature, the higher the volume resistivity and the lower the absolute value of the TCR, which is believed to be because the higher the annealing temperature, the greater the amount of SRO formed. However, if the annealing temperature is excessively high, the volume resistivity may decrease and the absolute value of the TCR may increase, which is believed to be because an excessively high annealing temperature causes excessive precipitation of the γ' phase. EXAMPLES

[0058] (Examples 1 to 6, Comparative Examples 1 to 6) [1. Sample preparation] The raw materials mixed to obtain the composition shown in Table 1 were melted in a vacuum induction furnace to obtain a 30 kg ingot. The ingot was then subjected to a homogenization treatment in which it was heated at 1200°C for 24 hours. Thereafter, it was forged at 1150°C and formed into a plate shape with a thickness of 10 mm. In addition, the plate-shaped hot-formed body was subjected to a solution treatment in which it was held at 1100°C for 2 hours and then air-cooled. Furthermore, the hot-formed body was cold-rolled at room temperature to obtain a cold-formed body with a thickness of 1.25 mm or 0.25 mm.

[0059] [Table 1]

[0060] Next, the obtained cold-formed bodies were subjected to a solution treatment under predetermined conditions. Furthermore, some of the samples were annealed under predetermined conditions after the solution treatment.

[0061] 2. Test Method 2.1. Cutting out test pieces Test pieces for measuring electrical resistance with dimensions of 1.25 mm x 3 mm x 90 mm or 0.25 mm x 3 mm x 90 mm (thickness as cold rolled) were cut out from the heat-treated compacts. Electric discharge cutting was used to cut the test pieces in order to avoid the introduction of distortion due to cutting. The cutting direction was the same as the rolling direction and the longitudinal direction of the test pieces.

[0062] [2.2. Measurement of volume resistivity and calculation of temperature coefficient of resistance] The volume resistivity (ρ) was measured by the four-terminal method. The measurement temperatures were 20°C and 155°C. The volume resistivity was measured three times at each temperature, and the average value was calculated. The measurement at 155°C was performed after the temperature was raised from 20°C to 155°C at a rate of 5°C / s and then held for 5 minutes after reaching 155°C. Furthermore, the temperature coefficient of resistance was calculated using the above-mentioned formula (1).

[0063] [2.3. Vickers hardness] The hardness was measured according to the Vickers hardness test method specified in JIS Z2244. The load was 4.9 N, and the measurement was performed at the center position in the plate thickness direction. The measurement was performed at five points, and the average value was used.

[0064] [3. Results] The results are shown in Table 2. The heat treatment conditions are also shown in Table 2. Furthermore, Figures 1 to 3 show the hardness, volume resistivity, and temperature coefficient of resistance of the resistors obtained in Examples 1 and 6 and Comparative Examples 1 to 4, respectively. The following can be seen from Table 2 and Figures 1 to 3.

[0065] In Table 2, the cooling method during solution treatment is as follows: "Furnace cooling" corresponds to an average cooling rate of about 50℃ / min. "Water cooling" corresponds to an average cooling rate of about 60,000℃ / min. "Gas quenching" corresponds to an average cooling rate of 100°C / min or more.

[0066] Regarding hardness, "◎" indicates that the material is between 170Hv and 220Hv. "○" indicates that the material is between 160Hv and 230Hv (except for ◎). "X" indicates less than 160Hv or more than 230Hv.

[0067] Regarding volume resistivity, "◎" indicates that the resistance is between 128μΩ·cm and 138μΩ·cm. "○" indicates that the resistance is between 125μΩ·cm and 150μΩ·cm (excluding the case of ◎). "×" indicates less than 125 μΩ·cm or more than 150 μΩ·cm.

[0068] Regarding temperature coefficient of resistance (TCR), "◎" indicates that the temperature is between -10 ppm / ℃ and 10 ppm / ℃. "○" indicates that the temperature is between -50 ppm / ℃ and 10 ppm / ℃ (excluding the case of ◎). "X" indicates less than -50 ppm / °C or more than 10 ppm / °C.

[0069] (1) In Comparative Example 1, the hardness exceeded 230 Hv and the TCR exceeded 10 ppm / ° C. This is believed to be because the steel was not solution-treated and contained a large amount of γ' phase. (2) In Comparative Example 2, the hardness exceeded 230 Hv and the TCR exceeded 10 ppm / °C. This is believed to be because the cooling rate was excessively slow due to furnace cooling during the solution treatment, and a large amount of γ' phase was precipitated during the cooling process. (3) In Comparative Example 3, the volume resistivity was less than 125 μΩ cm and the TCR exceeded 10 ppm / °C. This is believed to be because water cooling was performed during the solution treatment, resulting in an excessively fast cooling rate and a small amount of SRO formed.

[0070] (4) In Comparative Example 4, the TCR exceeded 10 ppm / °C. This is believed to be because the resistor was thin, so that the average cooling rate was excessively fast even when gas quenching was used as the cooling method during the solution treatment, resulting in a small amount of SRO formation. (5) In Comparative Example 5, the hardness exceeded 230 Hv and the TCR exceeded 10 ppm / ° C. This is believed to be because a large amount of γ′ phase was precipitated during annealing at 800° C.

[0071] (6) In Comparative Example 6, the TCR exceeded 10 ppm / ° C. This is believed to be because annealing was performed at 100° C., resulting in an insufficient amount of SRO formed. (7) All of Examples 1 to 6 had appropriate hardness, appropriate volume resistivity, and appropriate TCR.

[0072] [Table 2]

[0073] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention. [Industrial Applicability]

[0074] The resistor according to the present invention can be used as various resistors for use in power supply devices, electric vehicles, and the like.

Claims

1. A resistor having the following configuration: (1) The resistor is made of a Ni-based alloy, The Ni-based alloy is 15.0≦Cr≦25.0mass%, 1.0≦Al≦4.0mass%, 1.0≦Cu≦3.0mass%, 0≦Si≦1.5mass%, and 0≦Mn≦1.5mass% and the balance being Ni and unavoidable impurities. (2) The resistor is The Vickers hardness at 20°C is 160 Hv or more and 230 Hv or less, The volume resistivity at 20°C is 125 μΩ cm or more and 150 μΩ cm or less, The temperature coefficient of resistance at 20 to 155°C is -50 ppm / °C or more and 10 ppm / °C or less.

2. 2. The resistor according to claim 1, having a thickness of 3 mm or less.

3. The raw materials are melted and cast, 15.0≦Cr≦25.0mass%, 1.0≦Al≦4.0mass%, 1.0≦Cu≦3.0mass%, 0≦Si≦1.5mass%, and 0≦Mn≦1.5mass% a melting and casting step for obtaining an ingot comprising the balance Ni and unavoidable impurities; a homogenization heat treatment step of performing a homogenization heat treatment on the ingot to obtain a heat-treated body; a hot working step of hot working the heat-treated body to obtain a hot-formed body; a cold working step of performing cold working on the hot-formed body to obtain a cold-formed body; a heat treatment step of performing a heat treatment on the cold-formed body to remove distortion and to control the amount of precipitation of the γ' phase and the amount of formation of the short-range ordered phase, thereby obtaining the resistor according to claim 1; A method for manufacturing a resistor comprising the steps of:

4. The heat treatment step includes: A solution treatment process in which the cold-formed body is held at a heating temperature of 800° C. to 1200° C. for 30 seconds to 3 hours, and then cooled in a temperature range from the heating temperature to 400° C. at an average cooling rate capable of obtaining the resistor according to claim 1. The method for producing a resistor according to claim 3 , comprising:

5. The heat treatment step includes: a solution treatment step of holding the cold-formed body at a heating temperature of 800° C. or more and 1200° C. or less for 30 seconds or more and 3 hours or less, and then cooling the cold-formed body at an average cooling rate exceeding air cooling in a temperature range from the heating temperature to 400° C. to obtain a solution-treated body; an annealing step of holding the solution-treated body at a heating temperature of 200° C. to 700° C. for 30 seconds to 5 hours to obtain the resistor according to claim 1; The method for producing a resistor according to claim 3 , comprising:

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