阅读说明：本技术 低氧粉末冶金TiAl合金制件及其制备方法 (Low-oxygen powder metallurgy TiAl alloy part and preparation method thereof ) 是由 路新 张策 郭志猛 杨芳 刘博文 潘宇 徐伟 曲选辉 于 2020-05-21 设计创作，主要内容包括：本发明提供了一种低氧粉末冶金TiAl合金制件及其制备方法,该制备方法包括以下步骤：原料准备,选取块体TiH<Sub>2</Sub>、Al-Ti中间合金以及Al与其他合金元素的中间合金为原料；破碎处理,将所述原料混合后进行低温机械破碎处理,得到破碎后粉末；将所述破碎后粉末依次进行成形、真空烧结及无包套热等静压处理,得到TiAl合金制件。本发明通过对改进原料种类、破碎方式及优化制备流程实现了低氧含量高致密度的TiAl合金,制备得到的TiAl合金致密度大于99％,氧含量低于0.15wt.％。(The invention provides a low-oxygen powder metallurgy TiAl alloy part and a preparation method thereof, wherein the preparation method comprises the following steps: preparing raw materials, selecting block TiH 2 Al-Ti intermediate alloy and intermediate alloy of Al and other alloy elements are taken as raw materials; crushing, namely mixing the raw materials and then performing low-temperature mechanical crushing treatment to obtain crushed powder; and sequentially carrying out forming, vacuum sintering and non-sheath hot isostatic pressing treatment on the crushed powder to obtain a TiAl alloy part. The invention realizes the high-density and high-low-oxygen content by improving the types and the crushing modes of the raw materials and optimizing the preparation processThe density of the TiAl alloy prepared from the TiAl alloy is more than 99 percent, and the oxygen content is lower than 0.15 wt.%.)

1. A preparation method of a low-oxygen powder metallurgy TiAl alloy part is characterized by comprising the following steps:

s1: preparing raw materials, selecting block TiH₂Al-Ti intermediate alloy and intermediate alloy of Al and other alloy elements are taken as raw materials;

s2: crushing, namely mixing the raw materials and then performing low-temperature mechanical crushing treatment to obtain crushed powder;

s3: and (5) sequentially carrying out forming, vacuum sintering and non-sheath hot isostatic pressing treatment on the crushed powder obtained in the step S2 to obtain a TiAl alloy part.

2. The method for preparing the low-oxygen powder metallurgy TiAl alloy workpiece according to claim 1, wherein in step S1, the other elements are Cr, Nb, V, Y or Si.

3. The method for preparing the low-oxygen powder metallurgy TiAl alloy workpiece as claimed in claim 1, wherein in the step S1, the Al mass fraction of the Ti-Al intermediate alloy is 40-65 wt.%.

4. The method for preparing the low-oxygen powder metallurgy TiAl alloy workpiece as recited in claim 1, wherein in step S2, the low-temperature medium in the low-temperature mechanical crushing treatment is liquid argon.

5. The method for preparing the low-oxygen powder metallurgy TiAl alloy workpiece as recited in claim 1, wherein in step S2, the particle size of the crushed powder is 10-75 μm.

6. The method for preparing the TiAl alloy workpiece in the low-oxygen powder metallurgy according to claim 5, wherein in the step S2, the particle size of the crushed powder is 10-30 μm.

7. The method for preparing the low-oxygen powder metallurgy TiAl alloy workpiece according to the claim 1, wherein in the step S3, the forming process adopts a cold isostatic pressing forming process; wherein the pressing pressure is 150-200 MPa, and the pressure maintaining time is 10-30 s.

8. The method for preparing the low-oxygen powder metallurgy TiAl alloy workpiece according to claim 7, wherein in the step S3, the vacuum sintering treatment is specifically as follows: carrying out vacuum sintering densification on the blank obtained by the cold isostatic pressing; wherein the sintering temperature is 1300-1400 ℃, and the sintering time is 2-5 h.

9. The method for preparing the low-oxygen powder metallurgy TiAl alloy part according to claim 1, wherein in the step S3, the hot isostatic pressing treatment without capsule is specifically as follows: directly carrying out hot isostatic pressing on the blank subjected to the vacuum sintering treatment; wherein the hot isostatic pressing temperature of the non-sheathed tube is 1200-1300 ℃, the pressure is 150-200 MPa, and the sintering time is 2-5 h.

10. The low-oxygen powder metallurgy TiAl alloy part prepared by the preparation method of the low-oxygen powder metallurgy TiAl alloy part according to any one of claims 1-9, wherein the oxygen content of the TiAl alloy part is lower than 0.15 wt.%.

Technical Field

The invention relates to the technical field of powder metallurgy, in particular to a low-oxygen powder metallurgy TiAl alloy part and a preparation method thereof.

Background

The traditional Ni-based high-temperature alloy material has high density and large specific gravity, and can not meet the requirements of aerospace technology on skin and engine materials. TiAl intermetallic compounds (also called TiAl alloys) have been the first choice for the research of light high temperature structural materials due to their intrinsic characteristics such as excellent high temperature mechanical properties and lower density. Factors restricting the wide application of TiAl alloy mainly include alloy performance problem and production cost. The TiAl alloy prepared by the powder metallurgy method effectively overcomes the problems of serious macrosegregation, coarse and uneven structure, shrinkage porosity and the like of the TiAl alloy prepared by the fusion casting method, is a near-net forming technology for effectively preparing the TiAl alloy, and effectively saves the cost.

Most powder TiAl alloys adopt a prealloying method at present, the TiAl alloys prepared by the prealloying method have high density, fine microstructure and good room temperature plasticity, but the high cost of prealloying powder and the subsequent reinforced sintering process greatly increase the material cost. The mixed element method effectively overcomes the defects, and alloy elements can be added randomly according to needs. Patents CN201310099463.3 and CN102888530A provide a method for directly preparing TiAl alloy by using simple substance Ti powder and Al powder, but due to Kirkendall effect generated by uneven diffusion between Ti and Al, it is difficult to obtain high-density alloy material, and even cracking of sintered compact occurs. Thus, patent CN102825259A et al propose the use of TiH₂And Al powder, the method overcomes the Kirkendall effect and is beneficial to preparing TiAl alloy with high density. On the other hand, however, the simple substance aluminum powder is due to surface Al₂O₃The presence of a passivation layer allows the oxygen content of the alloy powder prepared by pre-reaction with elemental powder (>0.3 wt.%), which would be extremely highThe performance of the TiAl alloy is deteriorated.

Disclosure of Invention

The invention mainly aims to provide a low-oxygen powder metallurgy TiAl alloy part and a preparation method thereof, the preparation method adopts a low-temperature crushing mode to realize the preparation of intermediate alloy fine powder, aluminum element is introduced through Al-Ti alloy to reduce the Kinkendall holes generated between simple substance Ti powder and Al powder, the sintering density is increased, and meanwhile, oxygen element introduced through a passive film on the surface of the simple substance Al powder is reduced, so that the technical problem of higher powder oxygen content in the preparation process of the powder metallurgy TiAl alloy in the prior art is solved.

In order to achieve the above object, according to a first aspect of the present invention, a method for preparing a low-oxygen powder metallurgy TiAl alloy article is provided.

The preparation method of the low-oxygen powder metallurgy TiAl alloy part comprises the following steps:

s1: preparing raw materials, selecting block TiH₂Al-Ti intermediate alloy and intermediate alloy of Al and other alloy elements are taken as raw materials;

s2: crushing, namely mixing the raw materials and then performing low-temperature mechanical crushing treatment to obtain crushed powder;

s3: and (5) sequentially carrying out forming, vacuum sintering and non-sheath hot isostatic pressing treatment on the crushed powder obtained in the step S2 to obtain a TiAl alloy part.

Further, in step S1, the other element is Cr, Nb, V, Y, or Si.

Further, in step S1, the mass fraction of Al in the Ti — Al master alloy is 40 to 65 wt.%.

Further, in step S2, the cryogenic medium in the cryogenic mechanical crushing process is liquid argon.

Further, in step S2, the particle size of the crushed powder is 10 to 75 μm.

Further, in step S2, the particle size of the crushed powder is 10 to 30 μm.

Further, in step S3, the forming process adopts a cold isostatic pressing process; wherein the pressing pressure is 150-200 MPa, and the pressure maintaining time is 10-30 s.

Further, in step S3, the vacuum sintering process specifically includes: carrying out vacuum sintering densification on the blank obtained by the cold isostatic pressing; wherein the sintering temperature is 1300-1400 ℃, and the sintering time is 2-5 h.

Further, in step S3, the hot isostatic pressing treatment without capsule specifically includes: directly carrying out hot isostatic pressing on the blank subjected to the vacuum sintering treatment; wherein the hot isostatic pressing temperature of the non-sheathed tube is 1200-1300 ℃, the pressure is 150-200 MPa, and the sintering time is 2-5 h.

To achieve the above objects, according to a second aspect of the present invention, there is provided a low oxygen powder metallurgy TiAl alloy article.

The low-oxygen powder metallurgy TiAl alloy part prepared by the preparation method of the low-oxygen powder metallurgy TiAl alloy part is characterized in that the oxygen content of the TiAl alloy part is lower than 0.15 wt.%.

In the invention, Al-Ti intermediate alloy is adopted to introduce aluminum element, so that the increase of oxygen content caused by simple-substance aluminum powder is avoided, and meanwhile, in order to increase the brittleness of the Al-Ti alloy, a low-temperature crushing technology is innovatively introduced, so that alloy powder with finer granularity is obtained.

In addition, Al element in Al-Ti alloy is TiAl₂、TiAl₃And TiAl phase exists, so that the Cokendall holes in the subsequent sintering process are greatly reduced, and the sintering density is increased. The communicated holes disappear after vacuum sintering, and hot isostatic pressing can be directly carried out to realize complete densification.

Therefore, the TiAl alloy with high oxygen content and high compactness is realized by improving the types and crushing modes of raw materials and optimizing the preparation process, and experiments show that the compactness of the TiAl alloy prepared by the method is more than 99 percent, and the oxygen content is lower than 0.15 wt.%.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below. While exemplary embodiments of the present disclosure have been shown, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The invention discloses a preparation method of a low-oxygen powder metallurgy TiAl alloy part, which comprises the following steps:

s1: preparing raw materials, selecting block TiH₂(+80 mesh), Al-Ti intermediate alloy (+80 mesh) and intermediate alloy of Al and other alloy elements are used as raw materials, wherein the other elements are Cr, Nb, V, Y or Si; the mass fraction of Al in the Ti-Al intermediate alloy is 40-65 wt.%.

S2: crushing, namely mixing the raw materials according to the alloy component ratio and then performing low-temperature mechanical crushing treatment, wherein a low-temperature medium is liquid argon to obtain crushed powder; the particle size of the crushed powder is 10-75 mu m; preferably 10 to 30 μm.

S3: forming, namely forming the crushed powder obtained in the step S2, and specifically adopting a cold isostatic pressing process; wherein the pressing pressure is 150-200 MPa, and the pressure maintaining time is 10-30 s.

S4: vacuum sintering, wherein the blank obtained by cold isostatic pressing is subjected to vacuum sintering densification; wherein the sintering temperature is 1300-1400 ℃, and the sintering time is 2-5 h.

S5: performing non-sheath hot isostatic pressing treatment, namely directly performing hot isostatic pressing on the blank subjected to vacuum sintering treatment to obtain a TiAl alloy part; wherein the hot isostatic pressing temperature of the non-sheathed tube is 1200-1300 ℃, the pressure is 150-200 MPa, and the sintering time is 2-5 h.

The method for preparing the low-oxygen powder metallurgy TiAl alloy part in the application is described in detail by the specific embodiment.