Low-oxygen titanium alloy prepared through electromagnetic stirring in-situ deoxidation and method of low-oxygen titanium alloy

Abstract

The invention provides a low-oxygen titanium alloy prepared through electromagnetic stirring in-situ deoxidation and a method of the low-oxygen titanium alloy, and particularly relates to the technical field of titanium alloy preparation. The method for preparing the low-oxygen titanium alloy through electromagnetic stirring in-situ deoxidation comprises the steps that titanium powder and rare earth boride are mixed, and mixed powder is obtained; the mixed powder is roasted, and the titanium alloy is obtained; the roasting is carried out under an electromagnetic stirring condition. Electromagnetic stirring is used for assisting high-temperature melting, and the uniformity and compactness of the titanium alloy in the sintering process are improved; carrying out in-situ deoxidation by using the rare earth boride to generate a reinforced phase TiB of the titanium alloy; the high-oxygen titanium powder is used as the raw material, the cost is reduced, the roasting temperature, the content of the rare earth boride and the current intensity and the current frequency of electromagnetic stirring are controlled, and the titanium alloy with good performance is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy preparation, and in particular relates to a low-oxygen titanium alloy prepared by in-situ deoxidation using electromagnetic stirring and a method thereof. Background Art

[0002] Titanium has a strong affinity for oxygen, but as the oxygen concentration in titanium increases, the material's ductility decreases significantly. Strictly controlling oxygen levels to ensure final titanium product quality makes the production process more complex and expensive.

[0003] At present, powder metallurgy is one of the effective methods for preparing low-cost, high-performance titanium and titanium alloys in a short process in metallurgical technology. There are mainly two types of powder metallurgy for titanium: mixed element method and pre-alloy method. The mixed element method uses cheap hydrogenated dehydrogenated titanium powder or TiH 2 The powder is mixed with other alloy powders and then pressed into shape, and then vacuum sintered to obtain titanium or titanium alloy products. However, the titanium products obtained by the mixed element method have a high oxygen content. The pre-alloy method uses spherical titanium powder with low oxygen content as raw material, and obtains titanium products through high temperature and high pressure sintering. In terms of raw materials, the spherical titanium powder used in the pre-alloy method is ten times the price of ordinary titanium powder, and the sintering process needs to be carried out under high temperature and high pressure, which has extremely high requirements for equipment. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a low-oxygen titanium alloy prepared by in-situ deoxidation using electromagnetic stirring and a method thereof. The method provided by the present invention has a short process, low cost, simple operation, and the obtained titanium alloy has low oxygen content and good mechanical properties.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing titanium alloy by in-situ deoxidation using electromagnetic stirring, comprising the following steps:

[0007] mixing titanium powder and rare earth boride to obtain mixed powder;

[0008] calcining the mixed powder to obtain a titanium alloy;

[0009] The calcination is carried out under electromagnetic stirring conditions.

[0010] Preferably, the titanium powder is spherical and / or non-spherical titanium powder; the oxygen content of the titanium powder is lower than 4400 ppm; and the particle size of the titanium powder is ≤74 μm.

[0011] Preferably, the current intensity of the electromagnetic stirring is 200-300A, and the current frequency is 3-9Hz.

[0012] Preferably, the calcination temperature is 1700-1900°C;

[0013] The heat preservation time of the calcination is 10 to 16 hours;

[0014] The rate of heating to the calcination temperature is 5-10°C / min.

[0015] Preferably, the process of raising the temperature to the calcination temperature is carried out under electromagnetic stirring conditions.

[0016] Preferably, the mass of the rare earth boride accounts for 0.3-2.2% of the mass of the mixed powder.

[0017] Preferably, the rare earth in the rare earth boride includes Y, La, Ce, Sc or Nd.

[0018] Preferably, the mixed powder is preheated before calcination; the preheating temperature is 400-600°C, and the holding time is 4-8h; the rate of heating to the preheating temperature is 20-35°C / min.

[0019] Preferably, the step of mixing the titanium powder and the rare earth boride further includes drying.

[0020] The present invention also provides a titanium alloy prepared by the method described in the above technical solution, wherein the phase composition of the titanium alloy includes rare earth oxides and titanium and a TiB reinforcement phase doped in the titanium alloy;

[0021] The solid dissolved oxygen content in the titanium alloy is ≤3900ppm.

[0022] The present invention provides a method for preparing titanium alloy by electromagnetic stirring in-situ deoxidation, comprising the following steps: mixing titanium powder and rare earth boride to obtain mixed powder; calcining the mixed powder to obtain titanium alloy; the calcination is carried out under electromagnetic stirring conditions, the current intensity of the electromagnetic stirring is 200-300A, and the current frequency is 3-9Hz. The present invention utilizes electromagnetic stirring to make the various materials mix evenly, improve the internal quality of the titanium alloy, improve the tensile strength, impact strength and toughness of the alloy, reduce the segregation of alloy components, improve the surface quality of the alloy, assist high-temperature melting by electromagnetic stirring, and improve the uniformity and density of the titanium alloy during sintering; utilize rare earth boride for in-situ deoxidation, during the high-temperature calcination process, the solid solution oxygen in the titanium lattice will react with the rare earth elements in the rare earth boride to generate rare earth oxides, reduce the solid solution oxygen content in the titanium lattice, achieve the deoxidation effect, improve the ductility of the titanium alloy, and generate the reinforcing phase TiB of the titanium alloy, further improving the mechanical properties of the titanium alloy. The present invention breaks away from the limitation that the traditional pre-alloying method must use spherical titanium powder with low oxygen content as raw material, and is also applicable to non-spherical titanium powder raw materials with high oxygen content (the O content can be as high as 4400ppm), thereby reducing the production cost of low oxygen content titanium alloy. At the same time, the method provided by the present invention can be completed under normal pressure conditions, without the need for high temperature and high pressure equipment, with low cost and simple operation.

[0023] It can be seen from the data of the examples that when the oxygen content in the titanium powder raw material is 4200 ppm, the oxygen content of the titanium alloy prepared by the present invention is ≤3900 ppm, the tensile elongation is 18-24%, and the relative density is >95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 The present invention is a flow chart of the method for preparing low-oxygen titanium alloy by in-situ deoxidation using electromagnetic stirring. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing titanium alloy by in-situ deoxidation using electromagnetic stirring, comprising the following steps:

[0027] mixing titanium powder and rare earth boride to obtain mixed powder;

[0028] calcining the mixed powder to obtain a titanium alloy;

[0029] The calcination is carried out under electromagnetic stirring conditions.

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

[0031] The present invention mixes titanium powder and rare earth boride to obtain mixed powder.

[0032] In the present invention, the particle size of the titanium powder is preferably ≤74 μm. In the present invention, the oxygen content of the titanium powder is preferably less than 4400 ppm. In a specific embodiment of the present invention, the oxygen content of the titanium powder is preferably 4000-4400 ppm, and the morphology of the titanium powder is preferably spherical or non-spherical. The present invention can use titanium powders of different specifications such as spherical and non-spherical to prepare titanium alloys, and there is no strict requirement for the oxygen content of the titanium powder, which breaks through the traditional titanium powder metallurgy method's reliance on high-cost spherical low-oxygen titanium powder and solves the problem of high raw material costs.

[0033] In the present invention, the rare earth in the rare earth boride preferably includes Y, La, Ce, Sc or Nd.

[0034] In the present invention, the mass of the rare earth boride preferably accounts for 0.3-2.2% of the mass of the mixed powder. In a specific embodiment, the mass of the rare earth boride can account for 0.3%, 0.5%, 0.8%, 1%, 1.25%, 1.5%, 1.8%, 2% or 2.2% of the mass of the mixed powder.

[0035] In the present invention, the mixing of titanium powder and rare earth boride preferably includes drying, and the drying is preferably vacuum drying. In the present invention, the drying temperature is preferably 200-300° C., and in a specific embodiment, the drying temperature can be 200° C., 250° C. or 300° C. The present invention removes moisture from the mixed powder by drying.

[0036] After obtaining the mixed powder, the present invention bakes the mixed powder to obtain a titanium alloy.

[0037] In the present invention, the mixed powder is preferably preheated before calcination, and the rate of heating to the preheating temperature is preferably 5-10°C / min. In a specific embodiment, the rate of heating to the preheating temperature may be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min; the preheating temperature is preferably 400-600°C. In a specific embodiment, the preheating temperature may be 400°C, 450°C, 500°C, 550°C or 600°C; the preheating holding time is preferably 4-8h. In a specific embodiment, the preheating holding time is preferably 4h, 6h or 8h. In the present invention, the preheating is preferably carried out in an argon atmosphere. The present invention reduces the volume shrinkage during high-temperature sintering by preheating, thereby reducing the risk of cracks.

[0038] In the present invention, the rate of heating to the calcination temperature is preferably 5-10°C / min. In a specific embodiment, the rate of heating to the calcination temperature may be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min; the calcination temperature is preferably 1700-1900°C. In a specific embodiment, the calcination temperature may be 1700°C, 1750°C, 1800°C, 1850°C or 1900°C; the holding time of the calcination is preferably 10-16h. In a specific embodiment, the holding time of the calcination may be 10h, 12h, 14h or 16h. In the present invention, the calcination is preferably carried out in an argon atmosphere. During the calcination process, each component is sintered and solidified to obtain a titanium alloy. During the roasting process, the dissolved oxygen in the titanium lattice will react with the rare earth elements in the rare earth boride to generate rare earth oxides, which will reduce the dissolved oxygen content in the titanium lattice, achieve the deoxidation effect, and improve the mechanical properties of the titanium alloy. At the same time, the strengthening phase TiB of the titanium alloy will be generated, which will further improve the mechanical properties of the titanium alloy. The generated rare earth oxides will not affect the performance of the titanium alloy.

[0039] In the present invention, the preheating and calcining are preferably carried out under normal pressure.

[0040] In the present invention, the calcination is carried out under electromagnetic stirring conditions, and the current intensity of the electromagnetic stirring is preferably 200-300A. In a specific embodiment, the current intensity of the electromagnetic stirring can be 200A, 220A, 250A, 280A or 300A; the current frequency of the electromagnetic stirring is preferably 3-9Hz. In a specific embodiment, the current frequency of the electromagnetic stirring can be 3Hz, 4Hz, 5Hz, 6Hz, 7Hz, 8Hz or 9Hz.

[0041] In the present invention, the process of heating to the calcination temperature is preferably carried out under electromagnetic stirring. In a specific embodiment, when the preheating stage is over, the electromagnetic stirring is turned on, and the temperature is simultaneously raised to the calcination temperature. When the calcination is over, the electromagnetic stirring is turned off. Electromagnetic stirring is used to mix the melt evenly, improve the internal quality of the titanium alloy, improve the tensile strength, impact strength and toughness of the alloy, reduce the segregation of alloy components, improve the surface quality of the alloy, and improve the uniformity and density of the titanium alloy during sintering.

[0042] The present invention controls the roasting temperature, the content of rare earth boride, and the current intensity and current frequency of electromagnetic stirring within the above range, so as to obtain a titanium alloy with low oxygen content, good mechanical properties and high relative density. At the same time, the method provided by the present invention can be completed under normal pressure conditions, with low cost and simple operation.

[0043] The present invention also provides a titanium alloy prepared by the method described in the above technical solution, wherein the phase composition of the titanium alloy includes rare earth oxides and titanium and a TiB reinforcement phase doped in the titanium alloy.

[0044] In the present invention, the solid solution oxygen content in the titanium alloy is preferably ≤3900 ppm, the tensile elongation is preferably 18-24%, and the relative density is preferably >95%.

[0045] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with specific embodiments below. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Any modification, equivalent replacement, improvement, etc. made to the implementation methods of the present invention based on the technical essence and general principles of the present invention without creative work should be within the scope of protection of the present invention.

[0046] The flow chart of the method for preparing titanium alloy by electromagnetic stirring in-situ deoxidation provided by the present invention is as follows: Figure 1 As shown in the figure, titanium powder and YB 6 After mixing, dry vacuum drying is performed first, and then electromagnetic stirring assisted high temperature sintering is started to obtain a titanium alloy.

[0047] Example 1

[0048] Titanium powder with a particle size of ≤74 μm (oxygen content of 4200 ppm) and YB 6 The powders were mixed and dried at 60°C in a vacuum environment for 2 h to obtain a mixed powder, in which YB 6The powder mass accounts for 0.5% of the mixed powder mass. The mixed powder is preheated, heated to 400°C at 10°C / min and kept at this temperature for 6 hours, and then roasted, heated to 1700°C at 10°C / min and kept at this temperature for 12 hours. During the roasting process, electromagnetic stirring is performed, wherein the current intensity is 200A and the current frequency is 3Hz, to obtain a titanium alloy.

[0049] During the electromagnetic stirring process, the oxygen in the titanium powder will react with YB 6 The Y in the reaction produces Y 2 O 3 , achieving the deoxidation effect, and at the same time forming TiB as the strengthening phase of the titanium alloy. The obtained titanium alloy has an oxygen content of 3990ppm, a tensile elongation of 18%, and a density of 95.5%.

[0050] Example 2

[0051] Titanium powder with a particle size of ≤74 μm (oxygen content of 4200 ppm) and YB 6 The powders were mixed and dried at 60°C in a vacuum environment for 4 h to obtain a mixed powder, in which YB 6 The powder mass accounts for 1.25% of the mixed powder mass. The mixed powder is preheated, heated to 500°C at 8°C / min and kept for 6 hours, then roasted, and heated to 1800°C at 8°C / min for a second time and kept for 12 hours. During the roasting process, electromagnetic stirring is performed, the current intensity is 250A, and the current frequency is 6Hz to obtain a titanium alloy.

[0052] The obtained titanium alloy has an oxygen content of 3050 ppm, a tensile elongation of 19% and a density of 96.2%.

[0053] Example 3

[0054] Titanium powder with a particle size of ≤74 μm (oxygen content of 4200 ppm) and YB 6 The powders were mixed and dried at 60°C in a vacuum environment for 6 h to obtain a mixed powder, in which YB 6 The powder mass accounts for 2% of the mixed powder mass. The mixed powder is preheated, heated to 600°C at 5°C / min and kept at this temperature for 6 hours, and then roasted, heated to 1900°C at 5°C / min and kept at this temperature for 12 hours. During the roasting process, electromagnetic stirring is performed, the current intensity is 300A, and the current frequency is 6Hz, to obtain a titanium alloy.

[0055] The obtained titanium alloy has an oxygen content of 2100 ppm, a tensile elongation of 24%, and a density of 97.6%.

[0056] Comparative Example 1 (without electromagnetic stirring)

[0057] Titanium powder with a particle size of ≤74 μm (oxygen content of 4200 ppm) and YB6 The powders were mixed and dried at 60 °C in a vacuum environment for 2 h to obtain a mixed powder, in which YB 6 The mass of the powder accounts for 0.5% of the mass of the mixed powder. The mixed powder is preheated, heated to 400°C at 10°C / min and kept at this temperature for 6 hours, then roasted, and heated to 1700°C at 10°C / min for a second time and kept at this temperature for 12 hours to obtain a titanium alloy.

[0058] The obtained titanium alloy had an oxygen content of 4110 ppm and a tensile elongation of 14%.

[0059] Comparative Example 2 (without electromagnetic stirring)

[0060] Titanium powder with a particle size of ≤74 μm (oxygen content of 4200 ppm) and YB 6 The powders were mixed and dried at 60°C in a vacuum environment for 6 h to obtain a mixed powder, in which YB 6 The mass of the powder accounts for 2% of the mass of the mixed powder. The mixed powder is preheated, heated to 600°C at 5°C / min and kept at this temperature for 6 hours, then calcined, and heated to 1800°C at 5°C / min for a second time and kept at this temperature for 12 hours to obtain a titanium alloy.

[0061] The obtained titanium alloy had an oxygen content of 2980 ppm and a tensile elongation of 16%.

[0062] By comparing the titanium alloys obtained in Examples 1 and 3 with those obtained in Comparative Examples 1 to 2, it can be seen that at the same sintering temperature, the titanium alloy obtained by electromagnetic stirring assisted sintering has higher oxygen content and tensile elongation than the titanium alloy obtained without electromagnetic stirring assisted sintering, indicating that the method provided by the present invention can reduce the oxygen content in the titanium alloy and improve the mechanical properties of the titanium alloy.

[0063] 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 titanium alloy by in-situ deoxidation by electromagnetic stirring, characterized in that: The following steps are involved: mixing titanium powder and rare earth boride to obtain mixed powder; calcining the mixed powder to obtain a titanium alloy; The calcination is carried out under electromagnetic stirring conditions.

2. The method according to claim 1, characterized in that The titanium powder is spherical and / or non-spherical; the oxygen content of the titanium powder is lower than 4400 ppm; and the particle size of the titanium powder is ≤74 μm.

3. The method according to claim 1, characterized in that The current intensity of the electromagnetic stirring is 200-300A, and the current frequency is 3-9Hz.

4. The method according to claim 1, characterized in that: The calcination temperature is 1700-1900°C; The heat preservation time of the calcination is 10 to 16 hours; The rate of heating to the calcination temperature is 5-10°C / min.

5. The method according to claim 1, characterized in that: The process of heating up to the calcination temperature is carried out under electromagnetic stirring conditions.

6. The method according to claim 1, characterized in that The mass of the rare earth boride accounts for 0.3-2.2% of the mass of the mixed powder.

7. The method according to claim 1 or 6, characterized in that: The rare earth in the rare earth boride includes Y, La, Ce, Sc or Nd.

8. The method according to claim 1, characterized in that: The mixed powder is preheated before calcination; the preheating temperature is 400-600°C, and the insulation time is 4-8h; the rate of heating to the preheating temperature is 20-35°C / min.

9. The method according to claim 1, characterized in that: The method further comprises drying after mixing the titanium powder and the rare earth boride.

10. The titanium alloy obtained by the method according to any one of claims 1 to 9, characterized in that: The phase composition of the titanium alloy includes rare earth oxide, titanium and a TiB reinforcing phase doped in the titanium alloy; The solid dissolved oxygen content in the titanium alloy is ≤3900ppm.

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