A high-activity special alloy with good surface quality and preparation method thereof

Abstract

The present invention provides a high-activity special alloy with good surface quality and a preparation method thereof, belonging to the technical field of special alloy preparation. The present invention adopts a method of protecting a high-activity special alloy by combining metal foil with a high-activity metal. The outer layer protection uses metal foil for sealing and protecting the high-activity special alloy and combining with residual oxygen in a vacuum furnace; the inner layer material uses a high-activity metal with a high melting point that can absorb oxygen in the vacuum furnace, which can reduce the reaction of the high-activity special alloy with oxygen at high temperatures and prevent the high-activity special alloy from reacting with the inner layer material at high temperatures, thereby solving the problem of surface oxidation of the high-activity special alloy and ensuring the good surface quality of the high-activity special alloy. The results of the embodiment show that the high-activity special alloy prepared by the preparation method provided by the present invention has low and uniformly distributed oxygen content in different parts, and the organizational structure is uniformly distributed.

Description

Technical Field

[0001] The invention relates to the technical field of special alloy preparation, and in particular to a high-activity special alloy with good surface quality and a preparation method thereof. Background Art

[0002] High-activity special alloys refer to alloys that have a high affinity for oxygen and are prone to react with oxygen during their preparation, processing and use, which can deteriorate the processing and service performance of the material. High-activity special alloys are more likely to react with oxygen in the atmosphere under high-temperature heating during high-temperature heat treatment, resulting in a certain degree of oxygen permeation on the surface of the high-activity special alloy, which reduces the performance of the high-activity special alloy and affects its application.

[0003] At present, the anti-oxidation measures for heat treatment often use vacuum furnace or argon protection, or apply anti-oxidation coating for protection. Although the vacuum furnace or argon protection method can remove most of the oxygen in the atmosphere, there is still a slightly oxidizing atmosphere, which causes the high-activity special alloy to react with the surface of the high-activity special alloy under high temperature during heat treatment, resulting in a certain depth of oxygen permeation layer on the surface of the high-activity special alloy, which affects the processing performance and service performance of the alloy; although the anti-oxidation coating method can prevent oxidation to a certain extent, the high-activity special alloy is also easy to react with the coating material, affecting the performance and surface quality of the high-activity special alloy.

[0004] Therefore, how to solve the problem of surface oxidation of high-activity special alloys while ensuring the good surface quality of high-activity special alloys has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a high-activity special alloy with good surface quality and a preparation method thereof. The preparation method provided by the present invention solves the problem of surface oxidation of the high-activity special alloy and ensures the good surface quality of the high-activity special alloy.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a high-activity special alloy with good surface quality, comprising the following steps:

[0008] (1) Using a high-activity metal to coat a high-activity special alloy to obtain a coated object; the high-activity metal has a higher melting point than the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy;

[0009] (2) Wrapping the coating obtained in step (1) with metal foil to obtain a sample to be processed;

[0010] (3) heat treating the sample to be treated obtained in step (2) to obtain a high-activity special alloy with good surface quality.

[0011] Preferably, the chemical components of the high-activity special alloy in step (1) include at least three of Ta, Zr, Hf, Nb, Ti, Mo and Al.

[0012] Preferably, the highly active metal in step (1) is molybdenum.

[0013] Preferably, the metal foil in step (2) is tantalum foil or zirconium foil; the thickness of the metal foil is 0.02-0.05 mm.

[0014] Preferably, the heat treatment in step (3) is carried out at a holding temperature of 1200-1450°C, a holding time of 2-6 hours, and a vacuum degree of ≤5×10 -2 Pa.

[0015] Preferably, when the metal foil in step (2) is tantalum foil, the holding temperature of the heat treatment in step (3) is 1350-1450°C.

[0016] Preferably, when the metal foil in step (2) is zirconium foil, the holding temperature of the heat treatment in step (3) is 1200-1350°C.

[0017] Preferably, after the heat treatment in step (3) is completed, argon gas is filled in, followed by cooling, and finally taking out of the furnace to obtain a high-activity special alloy.

[0018] Preferably, the cooling time is 30-40 minutes; and the cooling end point temperature is less than 100°C.

[0019] The present invention provides a high-activity special alloy with good surface quality prepared by the preparation method described in the above technical solution.

[0020] The present invention provides a method for preparing a high-activity special alloy with good surface quality, comprising the following steps: (1) using a high-activity metal to coat the high-activity special alloy to obtain a coating; the high-activity metal has a higher melting point than the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy; (2) using a metal foil to wrap the coating obtained in step (1) to obtain a sample to be processed; (3) heat-treating the sample to be processed obtained in step (2) to obtain a high-activity special alloy with good surface quality. The present invention adopts a method of using a metal foil in combination with a high-activity metal to protect a high-activity special alloy, wherein the outer layer protection uses a metal foil for sealing the high-activity special alloy and combining with residual oxygen in a vacuum furnace; the inner layer material uses a high-activity metal with a high melting point that can absorb oxygen in the vacuum furnace, which can reduce the reaction of the high-activity special alloy with oxygen at high temperatures and prevent the high-activity special alloy from reacting with the inner layer material at high temperatures, thereby solving the problem of surface oxidation of the high-activity special alloy and ensuring the good surface quality of the high-activity special alloy. The results of the examples show that the high-activity special alloy prepared by the preparation method provided by the present invention has low and uniformly distributed oxygen content in different parts, and the organizational structure is uniformly distributed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the high-activity special alloy anti-oxidation coating provided by the present invention;

[0022] Figure 2 The surface oxygen content test diagram of the high-activity special alloy provided in Examples 1-2 and Comparative Example 1;

[0023] Figure 3 The surface optical metallographic structure of the high-activity special alloy provided in Example 1;

[0024] Figure 4 The surface optical metallographic structure of the high-activity special alloy provided in Example 2;

[0025] Figure 5 The optical metallographic structure of the surface layer of the high-activity special alloy provided in Comparative Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a high-activity special alloy with good surface quality, comprising the following steps:

[0027] (1) Using a high-activity metal to coat a high-activity special alloy to obtain a coated object; the high-activity metal has a higher melting point than the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy;

[0028] (2) Wrapping the coating obtained in step (1) with metal foil to obtain a sample to be processed;

[0029] (3) heat treating the sample to be treated obtained in step (2) to obtain a high-activity special alloy with good surface quality.

[0030] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art.

[0031] The present invention uses a high-activity metal to coat a high-activity special alloy to obtain a coated object.

[0032] The present invention has no special limitation on the specific type of the high-activity special alloy, and the high-activity special alloy well known to those skilled in the art can be used. As an embodiment of the present invention, the chemical composition of the high-activity special alloy can include at least three of Ta, Zr, Hf, Nb, Ti, Mo and Al, and can also be any combination of three, four or five of Ta, Zr, Hf, Nb, Ti, Mo and Al. The present invention has no special limitation on the composition of the chemical composition in the high-activity special alloy, and it can be determined according to the specific type of the required high-activity special alloy.

[0033] The present invention has no particular limitation on the specific preparation method of the high-activity special alloy, and the high-activity special alloy can be prepared by a preparation method well known to those skilled in the art. As an embodiment of the present invention, the high-activity special alloy can be obtained by a suspension melting molding process.

[0034] The present invention has no particular limitation on the specific size of the high-activity special alloy, as long as the high-activity metal can be completely coated. As an embodiment of the present invention, the high-activity special alloy can be in the shape of a disc; the diameter of the high-activity special alloy can be 50mm, 60mm, 70mm, 80mm or 90mm; the thickness of the high-activity special alloy can be 8mm, 9mm or 10mm.

[0035] In the present invention, the high-activity special alloy is preferably polished before coating. The present invention has no special limitation on the specific operation of the polishing, and it only needs to remove the surface oil stains.

[0036] In the present invention, the melting point of the high-activity metal is higher than that of the high-activity special alloy. The present invention can avoid the high-activity metal from melting and mixing with the high-activity special alloy during the heat treatment process by controlling the melting point of the high-activity metal to be higher than that of the high-activity special alloy.

[0037] In the present invention, the highly active metal reacts with oxygen but does not react with the highly active special alloy. By controlling the above conditions, the present invention can avoid the highly active metal from reacting with the highly active special alloy during the heat treatment process, thereby affecting the surface quality of the highly active special alloy. At the same time, the highly active metal can react with the oxygen remaining in the atmosphere during the heat treatment process, thereby avoiding the contact between oxygen and the highly active special alloy, thereby solving the problem of surface oxidation of the highly active special alloy and ensuring the surface quality of the highly active special alloy.

[0038] The present invention has no particular limitation on the specific type of the highly active metal, as long as it can meet the above requirements. As an embodiment of the present invention, the highly active metal may be molybdenum, titanium or zirconium.

[0039] The present invention has no particular limitation on the specific shape of the highly active metal, as long as it can coat the highly active special alloy. As an embodiment of the present invention, the highly active metal can be in the shape of a metal box or a metal sheet.

[0040] When the high-activity metal is in the shape of a metal box, the present invention has no special limitation on the specific size of the metal box, as long as the high-activity special alloy can be placed in the metal box. As an embodiment of the present invention, the length of the metal box can be 100 mm, 110 mm or 120 mm; the width of the metal box can be 100 mm, 110 mm or 120 mm; the height of the metal box can be 9 mm, 10 mm or 11 mm; the thickness of the metal box can be 0.9 mm, 1 mm or 1.1 mm.

[0041] In the present invention, when the high-activity metal is in the form of a metal sheet, the number of the metal sheets is preferably 2. The present invention has no particular limitation on the specific size of the metal sheet, as long as it can completely clamp and cover the high-activity special alloy. The present invention uses two metal sheets to completely cover the high-activity special alloy.

[0042] After obtaining the coating, the present invention uses metal foil to wrap the coating to obtain a sample to be processed.

[0043] In the present invention, the metal foil is preferably tantalum foil or zirconium foil; the thickness of the metal foil is preferably 0.02-0.05 mm. The present invention can further prevent the high-activity special alloy from contacting with oxygen by wrapping the coating with metal foil, thereby solving the problem of surface oxidation of the high-activity special alloy. As an embodiment of the present invention, the thickness of the metal foil can be 0.02 mm, 0.03 mm, 0.04 mm or 0.05 mm.

[0044] The present invention preferably uses a copper hammer or a wooden hammer to pound the folded part of the metal foil when it is wrapped. The present invention can ensure that the highly active metal is tightly wrapped and the surface of the metal foil is not damaged through the above operation.

[0045] After obtaining the sample to be processed, the present invention performs heat treatment on the sample to be processed to obtain a high-activity special alloy with good surface quality.

[0046] In the present invention, the heat treatment is preferably carried out in a vacuum furnace. The present invention has no particular limitation on the specific model of the vacuum furnace, and a commercially available vacuum furnace well known to those skilled in the art can be used.

[0047] In the present invention, the heat treatment holding temperature is preferably 1200-1450°C; the heat treatment holding time is preferably 2-6 hours; the heat treatment vacuum is preferably ≤5×10 -2 Pa.

[0048] In the present invention, when the metal foil is a tantalum foil, the holding temperature of the heat treatment is preferably 1350-1450°C; when the metal foil is a zirconium foil, the holding temperature of the heat treatment is preferably 1200-1350°C.

[0049] The present invention controls the heat treatment temperature to less than 1600°C, and the saturated vapor pressure of highly active metal molybdenum is higher than 10 -6 Pa, so the product will not stick to the molybdenum box during the heat treatment process, which is conducive to the subsequent removal of high-activity special alloys; when the heat treatment temperature is lower than 1350°C, the metal foil is preferably wrapped with zirconium foil. Zirconium has a stronger affinity for oxygen than tantalum and is cheaper, but it is easy to diffuse weld with the surface of the molybdenum box when used above 1350°C. When the surface foil material is removed after the heat treatment, the foil material is prone to damage, making it difficult to reuse; when the temperature is higher than 1350°C, the metal foil is preferably wrapped with tantalum foil to prevent the welding of tantalum foil and molybdenum box at high temperature, so it can be reused.

[0050] As an embodiment of the present invention, the holding temperature of the heat treatment may be 1200°C, 1250°C, 1300°C, 1350°C, 1400°C or 1450°C; the holding time of the heat treatment may be 2h, 3h, 4h, 5h or 6h.

[0051] After the heat treatment is completed, the present invention preferably fills the vacuum furnace with argon gas, then cools it, and finally takes it out of the furnace to obtain a high-activity special alloy.

[0052] The present invention has no special limitation on the specific amount of the argon gas, which can be determined according to the technical common sense of those skilled in the art. As an embodiment of the present invention, the amount of the argon gas can be such that the pressure of the vacuum furnace is 0.3-0.5 MPa. By introducing argon gas, the present invention can maintain an inert atmosphere in the vacuum furnace, which is beneficial to the subsequent removal of the high-activity special alloy and avoids secondary oxidation.

[0053] In the present invention, the cooling time is preferably 30-40 minutes; the cooling end temperature is preferably <100°C.

[0054] The schematic diagram of the high-activity special alloy anti-oxidation coating provided by the present invention is as follows Figure 1 As shown. Figure 1 It can be seen that the present invention places the high-activity special alloy into a molybdenum box and then wraps it with a zirconium foil or a tantalum foil, thereby isolating the high-activity special alloy from contact with oxygen in the atmosphere.

[0055] The present invention adopts a method of protecting a high-activity special alloy by using zirconium foil or tantalum foil in combination with a molybdenum box. The outer layer protection is made of ductile and highly active foil materials such as zirconium or tantalum, which are used for sealing and protecting the high-activity special alloy and combining with oxygen in a vacuum furnace. The inner layer material is made of a high-activity metal with a high melting point that can absorb oxygen in the vacuum furnace, which can reduce the reaction of the high-activity special alloy with oxygen at high temperature and prevent the high-activity special alloy from reacting with the inner layer material at high temperature, thereby solving the problem of surface oxidation of the high-activity special alloy and ensuring the good surface quality of the high-activity special alloy.

[0056] The present invention also provides a high-activity special alloy with good surface quality prepared by the preparation method described in the above technical solution.

[0057] The high-activity special alloy provided by the invention has low surface oxygen content and good surface quality.

[0058] 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.

[0059] Example 1

[0060] A method for preparing a high-activity special alloy with good surface quality comprises the following steps:

[0061] (1) grinding a disc-shaped high-activity special alloy to remove surface oil stains, cutting the surface every 0.2 mm to test the oxygen content, observing the surface structure, and then using a molybdenum box to coat the high-activity special alloy to obtain a coating; the melting point of the high-activity metal is higher than that of the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy; the high-activity special alloy is a NbZrTi high-activity special alloy prepared by a suspension smelting molding process, and the diameter of the high-activity special alloy is 90 mm and the thickness is 9 mm; the length of the metal box is 100 mm, the width is 100 mm, the height is 10 mm, and the thickness is 1 mm;

[0062] (2) Wrapping the coating obtained in step (1) with a metal foil, and using a copper hammer to pound the folded part of the metal foil to obtain a sample to be processed; the metal foil is tantalum foil, and the thickness of the metal foil is 0.05 mm;

[0063] (3) The sample to be processed obtained in step (2) is placed in a vacuum furnace and then evacuated to a vacuum degree of 5×10 -2 Pa, then heated to 1400°C for heat treatment for 4 hours, stopped heating, filled the vacuum furnace with argon to a pressure of 0.4 MPa, cooled for 40 minutes to a temperature of <100°C, and removed the tantalum foil and molybdenum box to obtain a high-activity special alloy with good surface quality. The surface of the high-activity special alloy was cut every 0.2 mm to test the oxygen content, and the surface structure was observed.

[0064] Example 2

[0065] A method for preparing a high-activity special alloy with good surface quality comprises the following steps:

[0066] (1) grinding a disc-shaped high-activity special alloy to remove surface oil stains, cutting the surface every 0.2 mm to test the oxygen content, observing the surface structure, and then using a molybdenum box to coat the high-activity special alloy to obtain a coating; the melting point of the high-activity metal is higher than that of the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy; the high-activity special alloy is a NbZrTi high-activity special alloy prepared by a suspension smelting molding process, and the diameter of the high-activity special alloy is 90 mm and the thickness is 9 mm; the length of the metal box is 100 mm, the width is 100 mm, the height is 10 mm, and the thickness is 1 mm;

[0067] (2) Wrapping the coated material obtained in step (1) with a metal foil, and using a copper hammer to pound the folded part of the metal foil to obtain a sample to be processed; the metal foil is a zirconium foil, and the thickness of the metal foil is 0.05 mm;

[0068] (3) The sample to be processed obtained in step (2) is placed in a vacuum furnace and then evacuated to a vacuum degree of 5×10 -2 Pa, then heated to 1300°C for heat treatment for 4 hours, stopped heating, filled the vacuum furnace with argon to a pressure of 0.4 MPa, cooled for 40 minutes to a temperature of <100°C, and removed the tantalum foil and molybdenum box to obtain a high-activity special alloy with good surface quality. The surface of the high-activity special alloy was cut every 0.2 mm to test the oxygen content, and the surface structure was observed.

[0069] Comparative Example 1

[0070] A method for preparing a high-activity special alloy comprises the following steps:

[0071] (1) grinding a disc-shaped high-activity special alloy to remove surface oil stains, cutting the surface every 0.2 mm to test the oxygen content, observing the surface structure, and then using a molybdenum box to coat the high-activity special alloy to obtain a coating; the melting point of the high-activity metal is higher than that of the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy; the high-activity special alloy is a NbZrTi high-activity special alloy prepared by a suspension smelting molding process, and the diameter of the high-activity special alloy is 90 mm and the thickness is 9 mm; the length of the metal box is 100 mm, the width is 100 mm, the height is 10 mm, and the thickness is 1 mm;

[0072] (2) The coated material obtained in step (1) is placed in a vacuum furnace and then evacuated to a vacuum degree of 5×10 - 2 Pa, then heated to 1400°C for heat treatment for 4 hours, stopped heating, filled the vacuum furnace with argon to a pressure of 0.4 MPa, cooled for 40 minutes to a temperature of <100°C, and removed the tantalum foil and molybdenum box to obtain a high-activity special alloy. The oxygen content of the high-activity special alloy was tested by cutting the surface every 0.2 mm, and the surface structure was observed.

[0073] The surface oxygen content of the high-activity special alloy provided in Examples 1-2 and Comparative Example 1 was tested, and the surface oxidation conditions obtained were as follows: Figure 2 As shown. Figure 2 It can be seen that after the present invention uses a molybdenum box for coating, and then wraps it with zirconium foil or tantalum foil, and the high-activity special alloy is heat treated, the surface oxygen content at different positions is not much different, and the oxygen content is low. The high-activity special alloy obtained by only coating with a molybdenum box but not wrapping with a zirconium foil or tantalum foil has a high oxygen content at the edge of the high-activity special alloy, and the oxygen content gradually decreases as it approaches the center, but it is still higher than the surface oxygen content of the high-activity special alloy obtained by the present invention, indicating that the preparation method provided by the present invention can effectively reduce the surface oxygen content of the high-activity special alloy.

[0074] The surface optical microstructures of the high-activity special alloys provided in Examples 1-2 and Comparative Example 1 are as follows: Figure 3~Figure 5 As shown. Figure 3 and Figure 4 It can be seen that the high-activity special alloy prepared by the preparation method provided by the present invention has a uniform organizational structure distribution both at the edge and inside the alloy. Figure 5 It can be seen that the organizational structure of the high-activity special alloy prepared in Comparative Example 1 near the edge of the alloy has obviously changed, resulting in the deterioration of the surface quality of the high-activity special alloy, indicating that the preparation method provided by the present invention can improve the surface quality of the high-activity special alloy.

[0075] 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 high-activity special alloy with good surface quality, comprising the following steps: (1) Using a high-activity metal to coat a high-activity special alloy to obtain a coated object; the high-activity metal has a higher melting point than the high-activity special alloy; the high-activity metal reacts with oxygen but does not react with the high-activity special alloy; (2) Wrapping the coating obtained in step (1) with metal foil to obtain a sample to be processed; (3) heat treating the sample to be treated obtained in step (2) to obtain a high-activity special alloy with good surface quality; The chemical components of the high-activity special alloy in step (1) include at least three of Ta, Zr, Hf, Nb, Ti, Mo and Al; In step (1), the highly active metal is molybdenum; In step (2), the metal foil is tantalum foil or zirconium foil; the thickness of the metal foil is 0.02-0.05 mm; The heat treatment in step (3) is carried out at a holding temperature of 1200-1450°C, a holding time of 2-6 hours, and a vacuum degree of ≤5×10 -2 Pa.

2. The preparation method according to claim 1, characterized in that: When the metal foil in step (2) is tantalum foil, the holding temperature of the heat treatment in step (3) is 1350-1450°C.

3. The preparation method according to claim 1, characterized in that: When the metal foil in step (2) is zirconium foil, the holding temperature of the heat treatment in step (3) is 1200-1350°C.

4. The preparation method according to claim 1, characterized in that: After the heat treatment in step (3) is completed, argon gas is filled in, followed by cooling, and finally taking out of the furnace to obtain a high-activity special alloy.

5. The preparation method according to claim 4, characterized in that: The cooling time is 30-40 minutes; the cooling end temperature is less than 100°C.

6. A high-activity special alloy with good surface quality prepared by the preparation method according to any one of claims 1 to 5.

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