A non-magnetic tungsten-nickel-iron alloy and its preparation method and application

Abstract

The present invention provides a non-magnetic tungsten-nickel-iron alloy and a preparation method and application thereof, belonging to the technical field of powder metallurgy. The present invention mixes tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder, and then performs pressing and molding, and finally sequentially performs sintering and vacuum heat treatment to obtain a non-magnetic tungsten-nickel-iron alloy. The present invention controls the Ni / Fe value in the tungsten-nickel-iron alloy to obtain a non-magnetic tungsten-nickel-iron alloy without affecting the overall performance of the alloy, and then obtains a non-magnetic tungsten-nickel-iron alloy with excellent mechanical properties through pressing and molding, sintering and vacuum heat treatment. The results of the embodiment show that the tungsten-nickel-iron alloy prepared by the present invention is non-magnetic, and has a tensile strength of ≥900MPa, a yield strength of ≥670MPa, an elongation of ≥15%, and an impact toughness of ≥100J / cm 2 .

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a non-magnetic tungsten-nickel-iron alloy and a preparation method and application thereof. Background Art

[0002] Tungsten alloy has the characteristics of high density, high strength and hardness, good electrical and thermal conductivity, low thermal expansion coefficient, strong radiation absorption ability, high pressure resistance and excellent electrical corrosion resistance, which is conducive to machining, welding, forging and heat treatment. It plays an irreplaceable role in the fields of national defense, aerospace, electronic information, energy, metallurgy, mechanical processing and nuclear industry. It occupies an important position in the national economy and has become one of the most active research fields in the field of materials science. At present, tungsten alloys are divided into two categories, namely tungsten nickel iron alloy and tungsten nickel copper alloy.

[0003] Among them, tungsten-nickel-iron alloy is a magnetic tungsten alloy made by sintering a mixture of tungsten powder, nickel powder, iron powder and other metal powders. This alloy has high sintering density, great strength and plasticity, and good weldability and machinability. It is widely used in aerospace, aviation, military, oil drilling, medicine and other fields, and has been unanimously praised by the people.

[0004] The tungsten-nickel-copper alloy material is a non-magnetic tungsten alloy, which is mainly used in some special occasions, such as gyroscope rotors and other devices that require working under the action of a magnetic field, which cannot be met by the performance of traditional magnetic tungsten-nickel-iron alloys. However, since the tensile strength of tungsten-nickel-copper is generally only about 800MPa, and the elongation is about 3%, the alloy has poor toughness, strength and plasticity, and low sintering density, and there is no nickel-iron activation sintering tungsten and other shortcomings, the instruments made of tungsten-nickel-copper alloy materials are more prone to damage, looseness, and reduced accuracy during use, and replacing these instruments and equipment will greatly increase the cost consumption.

[0005] Therefore, in order to increase the service life of the instrument, providing a tungsten-nickel-iron alloy that is non-magnetic and has excellent mechanical properties to replace the tungsten-nickel-copper alloy material has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] The purpose of the present invention is to provide a non-magnetic tungsten-nickel-iron alloy and a preparation method and application thereof. The tungsten-nickel-iron alloy prepared by the preparation method provided by the present invention not only has excellent mechanical properties, but also is different from the traditional magnetic tungsten-nickel-iron alloy. The tungsten-nickel-iron alloy prepared by the present invention is non-magnetic and can replace the tungsten-nickel-copper alloy with relatively low mechanical properties, and has good development prospects.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a non-magnetic tungsten-nickel-iron alloy, comprising the following steps:

[0009] (1) mixing tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder to obtain a mixed powder; the mass ratio of Ni to Fe in the mixed powder is (6-12):1;

[0010] (2) pressing the mixed powder obtained in step (1) to obtain a compact to be sintered;

[0011] (3) The sintered compact obtained in step (2) is subjected to sintering and vacuum heat treatment in sequence to obtain a non-magnetic tungsten-nickel-iron alloy.

[0012] Preferably, in step (1), the tungsten powder has a Fischer-Strauss particle size of 2.5-3.5 μm, the nickel powder has a Fischer-Strauss particle size of 2.2-2.8 μm, the iron powder has a Fischer-Strauss particle size of 5-8 μm, the cobalt powder has a Fischer-Strauss particle size of 0.9-1.5 μm, and the manganese powder has a Fischer-Strauss particle size of 7-9 μm.

[0013] Preferably, the chemical composition of the mixed powder in step (1) is, by mass percentage, 85-95% W, 3-15% Ni, 0.5-3% Fe, 0.3-0.6% Co and 0.02-0.05% Mn.

[0014] Preferably, the mass ratio of Ni to Fe in the mixed powder is (8-11.5):1.

[0015] Preferably, the holding pressure of the compression molding in step (2) is 160 to 200 MPa, and the holding time of the compression molding is 120 to 240 s.

[0016] Preferably, the sintering in step (3) is carried out in a high-temperature molybdenum wire furnace.

[0017] Preferably, the sintering temperature is 1440-1550° C., the sintering speed is 6-26 mm / min, and the sintering method is semi-naked sintering.

[0018] Preferably, the holding temperature of the vacuum heat treatment in step (3) is 1100-1250°C, and the vacuum degree of the vacuum heat treatment is less than 6.5×10 -2 Pa, the holding time of vacuum heat treatment is 2 to 4 hours.

[0019] The present invention provides a non-magnetic tungsten-nickel-iron alloy prepared by the preparation method described in the above technical solution.

[0020] The present invention provides the application of the non-magnetic tungsten-nickel-iron alloy described in the above technical solution in a device working under the action of a magnetic field.

[0021] The invention provides a method for preparing a non-magnetic tungsten-nickel-iron alloy, comprising the following steps: (1) mixing tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder to obtain a mixed powder; the mass ratio of Ni to Fe in the mixed powder is (6-12):1; (2) pressing the mixed powder obtained in the step (1) to obtain a sintered compact; (3) sequentially sintering and vacuum heat treating the sintered compact obtained in the step (2) to obtain a non-magnetic tungsten-nickel-iron alloy. The present invention uses tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder as raw materials, and controls the mass ratio of Ni to Fe in the mixed powder to be (6-12): 1, which can ensure that the prepared tungsten-nickel-iron alloy is non-magnetic and will not affect its mechanical properties; a high-density blank can be obtained by pressing and molding, which is not easy to produce defects such as bubbles and cracks during the subsequent sintering process, and ensures that the internal crystal structure of the tungsten-nickel-iron alloy is sintered more uniformly; finally, hydrogen embrittlement can be removed by vacuum heat treatment, and the mechanical properties of the tungsten-nickel-iron alloy are further improved, thereby obtaining a tungsten-nickel-iron alloy with both non-magnetic and excellent mechanical properties, which can replace the tungsten-nickel-copper alloy with low mechanical properties and has good development prospects; in addition, the preparation method of the present invention is simple, low in consumption cost, and convenient for large-scale industrial promotion. The results of the embodiment show that the non-magnetic tungsten-nickel-iron alloy prepared by the preparation method provided by the present invention is non-magnetic, and has a tensile strength of ≥900MPa, a yield strength of ≥670MPa, an elongation of ≥15%, and an impact toughness of ≥100J / cm 2 . DETAILED DESCRIPTION

[0022] The present invention provides a method for preparing a non-magnetic tungsten-nickel-iron alloy, comprising the following steps:

[0023] (1) mixing tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder to obtain a mixed powder; the mass ratio of Ni to Fe in the mixed powder is (6-12):1;

[0024] (2) pressing the mixed powder obtained in step (1) to obtain a compact to be sintered;

[0025] (3) The sintered compact obtained in step (2) is subjected to sintering and vacuum heat treatment in sequence to obtain a non-magnetic tungsten-nickel-iron alloy.

[0026] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared using preparation processes well known to those skilled in the art.

[0027] The invention mixes tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder to obtain mixed powder.

[0028] In the present invention, the iron powder is preferably carbonyl iron powder.

[0029] In the present invention, the Fischer-Strauss particle size of the tungsten powder is preferably 2.5-3.5 μm; the Fischer-Strauss particle size of the nickel powder is preferably 2.2-2.8 μm; the Fischer-Strauss particle size of the iron powder is preferably 5-8 μm; the Fischer-Strauss particle size of the cobalt powder is preferably 0.9-1.5 μm; and the Fischer-Strauss particle size of the manganese powder is preferably 7-9 μm. The present invention controls the particle size of the metal powder, thereby controlling the microstructure and properties of the powder during compression molding, shrinkage during sintering, and vacuum heat treatment, and ensures the consistency of the organization and stability of the properties of the tungsten-nickel-iron alloy by controlling the particle size.

[0030] In the present invention, the mixing is preferably carried out in a mixer; the mixing time is preferably 10 to 22 hours, more preferably 12 to 20 hours; and tungsten alloy balls are preferably added to the mixer during the mixing process. The present invention has no special restrictions on the specific chemical composition, size and dosage of the tungsten alloy balls, which can be determined according to the technical common sense of those skilled in the art. The present invention can make the alloy powder mixed more uniformly by controlling the mixing method.

[0031] In the present invention, the chemical composition of the mixed powder is preferably: W85-95%, Ni 3-15%, Fe 0.5-3%, Co 0.3-0.6% and Mn 0.02-0.05%, more preferably: W 90-93%, Ni 4-12%, Fe 0.75-2.5%, Co 0.4-0.5% and Mn 0.03-0.04%, and further preferably: W 90-93%, Ni8-10%, Fe 0.9-1.5%, Co 0.4-0.5% and Mn0.03-0.04%. The present invention can lay a foundation for the excellent mechanical properties of the tungsten-nickel-iron alloy by controlling the chemical composition of the mixed powder, and can eliminate the magnetism of the tungsten-nickel-iron alloy by coordinating with the subsequent preparation process.

[0032] In the present invention, the mass ratio of Ni to Fe in the mixed powder is (6-12): 1, preferably (8-11.5): 1, and more preferably (9-11.5): 1. The present invention can eliminate the magnetism in the tungsten-nickel-iron alloy by controlling the ratio of nickel and iron, thereby obtaining a non-magnetic tungsten-nickel-iron alloy.

[0033] After obtaining the mixed powder, the present invention performs compression molding on the mixed powder to obtain a compact to be sintered.

[0034] In the present invention, the compression molding is preferably performed in a cold isostatic press. The present invention has no particular limitation on the specific model of the cold isostatic press, and a commercial product well known to those skilled in the art can be used.

[0035] In the present invention, the method of loading the mixed powder into the cold isostatic press is preferably: loading the mixed powder into the rubber sleeve of the cold isostatic press, compacting and packaging it with a press, and then lifting it with a crane and placing it into the cold isostatic press to start pressing and molding.

[0036] In the present invention, the holding pressure of the press molding is preferably 160-200MPa, more preferably 170-190MPa, and further preferably 180MPa; the holding time of the press molding is preferably 120-240s, more preferably 150-210s, and further preferably 160-180s. The present invention can improve the compactness of the green compact to be sintered by controlling the parameters of the press molding, thereby further improving the mechanical properties of the tungsten-nickel-iron alloy.

[0037] After obtaining the compact to be sintered, the present invention sequentially performs sintering and vacuum heat treatment on the compact to be sintered to obtain a non-magnetic tungsten-nickel-iron alloy.

[0038] In the present invention, the sintering is preferably carried out in a high-temperature molybdenum wire furnace. The present invention has no particular limitation on the specific model of the high-temperature molybdenum wire furnace, and a commercial product well known to those skilled in the art can be used.

[0039] In the present invention, the sintering temperature is preferably 1440-1550°C, more preferably 1450-1500°C; the sintering push speed is preferably 6-26mm / min, more preferably 8-24mm / min, and further preferably 10-20mm / min; the sintering method is preferably semi-naked sintering. In the present invention, the sintering atmosphere is preferably a reducing atmosphere; the reducing atmosphere is preferably hydrogen. The present invention has no special limitation on the pressure or flow rate of the reducing atmosphere, which can be determined according to the technical common sense of those skilled in the art. The present invention can ensure that the internal temperature of the furnace of the high-temperature molybdenum wire furnace is uniform by controlling the sintering method and parameters, and at the same time facilitate the observation of the sintering process of the blank, optimize the process at any time, and control the reducing atmosphere of the furnace of the high-temperature molybdenum wire furnace, so that it is not easy to produce defects such as bubbles and cracks, and ensure that the internal crystal structure of the tungsten-nickel-iron alloy is sintered more uniformly.

[0040] In the present invention, the holding temperature of the vacuum heat treatment is preferably 1100-1250°C, more preferably 1150-1200°C; the vacuum degree of the vacuum heat treatment is preferably <6.5×10 -2 The holding time of the vacuum heat treatment is preferably 2 to 4 hours, more preferably 3 hours. The present invention can remove hydrogen embrittlement and improve the mechanical properties of the tungsten-nickel-iron alloy through vacuum heat treatment.

[0041] The invention adopts tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder as raw materials, and controls the mass ratio of Ni to Fe in the mixed powder to be (6-12):1, so that the prepared tungsten-nickel-iron alloy is non-magnetic and its mechanical properties are not affected; a high-density blank can be obtained by pressing and forming, so that it is not easy to generate defects such as bubbles and cracks in the subsequent sintering process, and the internal crystal structure of the tungsten-nickel-iron alloy is sintered more uniformly; finally, hydrogen embrittlement can be removed by vacuum heat treatment, and the mechanical properties of the tungsten-nickel-iron alloy are further improved, so as to obtain a tungsten-nickel-iron alloy with both non-magnetic properties and excellent mechanical properties.

[0042] The present invention provides a non-magnetic tungsten-nickel-iron alloy prepared by the preparation method described in the above technical solution. In the present invention, the chemical composition of the non-magnetic tungsten-nickel-iron alloy is preferably: W85-95%, Ni 3-15%, Fe0.5-3%, Co 0.3-0.6% and Mn 0.02-0.05% by mass percentage, more preferably: W 90-93%, Ni 4-12%, Fe0.75-2.5%, Co 0.4-0.5% and Mn 0.03-0.04%, further preferably: W 90-93%, Ni 8-10%, Fe 0.9-1.5%, Co 0.4-0.5% and Mn 0.03-0.04%.

[0043] The non-magnetic tungsten-nickel-iron alloy provided by the present invention is non-magnetic, and has a tensile strength of ≥900MPa, a yield strength of ≥670MPa, an elongation of ≥15%, and an impact toughness of ≥100J / cm 2 It can be seen that the tungsten-nickel-iron alloy provided by the present invention has both non-magnetic properties and excellent mechanical properties.

[0044] The present invention provides the application of the non-magnetic tungsten-nickel-iron alloy described in the above technical solution in a device working under the action of a magnetic field. The present invention has no special limitation on the specific manner of the application, and the application manner familiar to those skilled in the art can be adopted.

[0045] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] A method for preparing a non-magnetic tungsten-nickel-iron alloy comprises the following steps:

[0048] (1) Tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder are mixed in a mixer for 12 hours, and tungsten alloy balls are added during the mixing process to obtain a mixed powder; the tungsten powder has a Fischer-Strauss particle size of 3.0 μm; the nickel powder has a Fischer-Strauss particle size of 2.2 μm; the iron powder is carbonyl iron powder, and the iron powder has a Fischer-Strauss particle size of 6 μm; the cobalt powder has a Fischer-Strauss particle size of 1.2 μm; the manganese powder has a Fischer-Strauss particle size of 7 μm; the chemical composition of the mixed powder is, by mass percentage, 93% W, 5.55% Ni, 0.9% Fe, 0.5% Co and 0.05% Mn; the mass ratio of Ni to Fe in the mixed powder is 6.16:1;

[0049] (2) The mixed powder obtained in step (1) is loaded into a rubber sleeve of a cold isostatic press, compacted and packaged with a press, and then lifted by a crane and placed in a cold isostatic press to start press molding to obtain a green compact to be sintered; the press molding method is preferably isostatic pressing; the holding pressure of the press molding is 180 MPa; and the holding time of the press molding is 120 s;

[0050] (3) Sintering the green compact obtained in step (2) in a high-temperature molybdenum wire furnace in a hydrogen atmosphere, and then performing vacuum heat treatment to obtain a non-magnetic tungsten-nickel-iron alloy; the sintering temperature is 1475° C.; the sintering push speed is 10 mm / min; the sintering method is semi-bare sintering; the holding temperature of the vacuum heat treatment is 1250° C.; the vacuum degree of the vacuum heat treatment is less than 6.5×10 -2 Pa; the holding time of the vacuum heat treatment is 3h.

[0051] Example 2

[0052] A method for preparing a non-magnetic tungsten-nickel-iron alloy comprises the following steps:

[0053] (1) Tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder are mixed in a mixer for 22 hours, and tungsten alloy balls are added during the mixing process to obtain a mixed powder; the tungsten powder has a Fischer-Strauss particle size of 2.8 μm; the nickel powder has a Fischer-Strauss particle size of 2.5 μm; the iron powder is carbonyl iron powder, and the iron powder has a Fischer-Strauss particle size of 6.8 μm; the cobalt powder has a Fischer-Strauss particle size of 1.0 μm; the manganese powder has a Fischer-Strauss particle size of 7.5 μm; the chemical composition of the mixed powder is, by mass percentage, 90% W, 8.62% Ni, 0.75% Fe, 0.6% Co and 0.03% Mn; the mass ratio of Ni to Fe in the mixed powder is 11.5:1;

[0054] (2) The mixed powder obtained in step (1) is loaded into a rubber sleeve of a cold isostatic press, compacted and packaged with a press, and then lifted by a crane and placed in a cold isostatic press to start press molding to obtain a green compact to be sintered; the press molding method is preferably isostatic pressing; the holding pressure of the press molding is 200 MPa; and the holding time of the press molding is 240 s;

[0055] (3) Sintering the green compact obtained in step (2) in a high-temperature molybdenum wire furnace in a hydrogen atmosphere, and then performing vacuum heat treatment to obtain a non-magnetic tungsten-nickel-iron alloy; the sintering temperature is 1460° C.; the sintering push speed is 26 mm / min; the sintering method is semi-naked sintering; the holding temperature of the vacuum heat treatment is 1200° C.; the vacuum degree of the vacuum heat treatment is less than 6.5×10 -2 Pa; the holding time of the vacuum heat treatment is 4h.

[0056] Example 3

[0057] A method for preparing a non-magnetic tungsten-nickel-iron alloy comprises the following steps:

[0058] (1) Tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder are mixed in a mixer for 10 hours, and tungsten alloy balls are added during the mixing process to obtain a mixed powder; the tungsten powder has a Fischer-Strauss particle size of 2.8 μm; the nickel powder has a Fischer-Strauss particle size of 2.6 μm; the iron powder is carbonyl iron powder, and the iron powder has a Fischer-Strauss particle size of 6.8 μm; the cobalt powder has a Fischer-Strauss particle size of 1.0 μm; the manganese powder has a Fischer-Strauss particle size of 7.5 μm; the chemical composition of the mixed powder is, by mass percentage, 95% W, 4.15% Ni, 0.5% Fe, 0.3% Co and 0.05% Mn; the mass ratio of Ni to Fe in the mixed powder is 8.3:1;

[0059] (2) The mixed powder obtained in step (1) is loaded into a rubber sleeve of a cold isostatic press, compacted and packaged with a press, and then lifted by a crane and placed in a cold isostatic press to start press molding to obtain a green compact to be sintered; the press molding method is preferably isostatic pressing; the holding pressure of the press molding is 160 MPa; and the holding time of the press molding is 120 s;

[0060] (3) Sintering the green compact obtained in step (2) in a high-temperature molybdenum wire furnace in a hydrogen atmosphere, and then performing vacuum heat treatment to obtain a non-magnetic tungsten-nickel-iron alloy; the sintering temperature is 1530° C.; the sintering push speed is 6 mm / min; the sintering method is semi-bare sintering; the holding temperature of the vacuum heat treatment is 1100° C.; the vacuum degree of the vacuum heat treatment is less than 6.5×10 -2 Pa; the holding time of the vacuum heat treatment is 2h.

[0061] Comparative Example 1

[0062] Traditional WNiCu alloy.

[0063] Comparative Example 2

[0064] The chemical element composition of the traditional 95WNiFe alloy is 95wt.% W, 3.5wt.% Ni and 1.5wt.% Fe.

[0065] The performance of the non-magnetic tungsten-nickel-iron alloys prepared in Examples 1 to 3 and the traditional tungsten alloys provided in Comparative Examples 1 to 2 were tested according to national standards, and the results are shown in Table 1:

[0066] Table 1 Properties of the non-magnetic tungsten-nickel-iron alloys prepared in Examples 1 to 3 and the conventional tungsten alloys provided in Comparative Examples 1 to 2

[0067]

[0068] It can be seen from Table 1 that when the Ni / Fe value of the present invention is controlled to exceed 6.0, the obtained tungsten-nickel-iron alloy is non-magnetic, and the present invention can improve the toughness of the tungsten-nickel-iron alloy by adding the Co element; the performance of the tungsten-nickel-iron alloy prepared by the preparation process provided by the present invention far exceeds that of ordinary tungsten-nickel-copper, and its tensile strength is ≥900MPa, yield strength is ≥670MPa, elongation is ≥15%, and impact toughness is ≥100J / cm 2 , with good process performance.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a non-magnetic tungsten-nickel-iron alloy, comprising the following steps: (1) Mixing tungsten powder, nickel powder, iron powder, cobalt powder and manganese powder to obtain a mixed powder; the mass ratio of Ni to Fe in the mixed powder is (6-12):1; (2) pressing the mixed powder obtained in step (1) to obtain a compact to be sintered; (3) sintering and vacuum heat treating the green compact obtained in step (2) to obtain a non-magnetic tungsten-nickel-iron alloy; The chemical composition of the mixed powder in step (1) is: W 85-95%, Ni 3-15%, Fe 0.5-3%, Co 0.3-0.6% and Mn 0.02-0.05%; In step (3), the sintering is carried out in a high-temperature molybdenum wire furnace, the sintering temperature is 1440-1550° C., the sintering push speed is 6-26 mm / min, and the sintering method is semi-naked sintering; The holding temperature of the vacuum heat treatment in step (3) is 1100-1250°C, and the vacuum degree of the vacuum heat treatment is less than 6.5×10 -2 Pa, the holding time of vacuum heat treatment is 2~4h.

2. The preparation method according to claim 1, characterized in that: In the step (1), the Fischer-Strauss particle size of the tungsten powder is 2.5-3.5 μm, the Fischer-Strauss particle size of the nickel powder is 2.2-2.8 μm, the Fischer-Strauss particle size of the iron powder is 5-8 μm, the Fischer-Strauss particle size of the cobalt powder is 0.9-1.5 μm, and the Fischer-Strauss particle size of the manganese powder is 7-9 μm.

3. The preparation method according to claim 1, characterized in that: The mass ratio of Ni to Fe in the mixed powder is (8-11.5):

1.

4. The preparation method according to claim 1, characterized in that: The holding pressure of the pressing molding in the step (2) is 160-200 MPa, and the holding time of the pressing molding is 120-240 s.

5. The non-magnetic tungsten-nickel-iron alloy prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the non-magnetic tungsten-nickel-iron alloy according to claim 5 in a device operating under the action of a magnetic field.

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