CN102825259B - Method for preparing TiAl inter-metallic compound powder by using titanium hydride powder - Google Patents

Abstract

The invention belongs to the technical field of powder metallurgy, and relates to a method for preparing TiAl intermetallic compound powder with titanium hydride powder. The preparation steps are as follows: Weigh titanium hydride powder and aluminum powder according to the atomic ratio of Ti and Al of 1:1, and mix them evenly through high-energy ball milling. During the process, toluene is added as a control agent to prevent oxidation, and then the vacuum degree is 4.0×10 ^{- 2} ~ 4.0×10 ^-3 Pa rapid heating tubular electric furnace for sintering with a certain process, after cooling with the furnace to obtain TiAl intermetallic compounds. The process of the invention is simple, and the titanium hydride powder with relatively cheap raw materials is diffused and sintered at a low temperature, and after simple grinding, a very high-purity TiAl intermetallic compound powder can be obtained, and the powder can be shaped by common methods of powder metallurgy, etc. Subsequent processing.

Description

A method for preparing TiAl intermetallic compound powder with titanium hydride powder

technical field

The invention belongs to the technical field of powder metallurgy, and relates to a method for preparing TiAl intermetallic compound powder with titanium hydride powder.

Background technique

With the rapid development of aerospace and automobile fields, titanium-aluminum intermetallic compounds have become the most promising high-temperature structural materials in the future due to their excellent performance, and are widely used in aerospace and other fields, such as various components in aerospace engines. various parts, engine parts in high-end sports cars, etc.

The process of preparing TiAl-based alloys by powder metallurgy can be divided into element powder method and pre-alloy powder method according to the raw material powder. Elemental powder is used as raw material, and the cost is low, but due to the Kirkendall effect, a large volume expansion will occur during reaction sintering, so it is difficult to obtain high-density materials by pressureless sintering, and because of its high oxygen and impurity content, the sintering performance is poor Poor, the performance of the alloy parts is weakened, although hot pressing or hot isostatic pressing can make the material higher density, but the cost is more expensive; the composition uniformity of the pre-alloyed powder method is good, oxygen and impurities The content is low and the mechanical properties are good, but the current methods of producing TiAl intermetallic compounds are generally produced by mechanical alloying, vacuum smelting and other methods. Among these methods, mechanical alloying is easy to produce various inclusions; vacuum smelting has the disadvantages of component segregation, difficult operation, and easy occurrence of various inclusions. Therefore, it is very necessary to discuss the method of preparing alloy powder and develop a new process for the production of alloy powder, so that the produced alloy powder has lower cost, fewer inclusions, higher purity, and simpler preparation process.

Wang Jun et al. used titanium powder and aluminum powder obtained by dehydrogenation of titanium hydride as raw materials to obtain TiAl alloy powder by diffusion reaction in a tube furnace after mechanical mixing. In addition, titanium hydride is more expensive than titanium hydride, and titanium powder is more active than titanium hydride powder, resulting in a higher content of oxygen and other inclusions in titanium powder, which is very unfavorable for further processing.

Contents of the invention

The object of the present invention is to provide a method for preparing TiAl intermetallic compound powder with titanium hydride powder.

Compared with titanium powder, titanium hydride powder has a lower price, and TiAl alloy powder is obtained by sintering at a low sintering temperature, and the alloy powder obtained by sintering at last has very high purity, and the operation process of this method is very simple. Therefore, it can be used as a method for preparing high-purity TiAl alloy powder.

A method for preparing TiAl intermetallic compound powder with titanium hydride powder, characterized in that:

1) Weigh titanium hydride powder and aluminum powder according to the atomic ratio of Ti and Al of 1:1, and homogenize them in a high-energy ball mill; add toluene as a control agent during the process to prevent oxidation;

2) Put the above uniformly mixed materials into a rapid heating tubular electric furnace with a vacuum degree of ≤4.0×10 ^-2 Pa. The diffusion reaction temperature is 100-650°C, and the heating rate is 2~4°C/min. The time is 10 minutes to 4 hours; the purpose of the low-rate heating diffusion reaction is for the diffusion reaction of aluminum powder and the dehydrogenation of titanium hydride powder. The sintering temperature is 750-1000°C, the heating rate is 4-8°C/min, and the holding time is 1-5 hours. The higher temperature holding is for alloying between titanium and aluminum.

3) After heating, cool with the furnace and grind to obtain TiAl intermetallic compound powder with an average particle size of 10-50 μm.

Since the dehydrogenation of titanium hydride is carried out first in the low temperature holding stage or in the heating process, the various defects of the mixed powder after vibration ball milling are reduced and part of the energy is released, and the diffusion of Ti and Al mixed powder is more sensitive to the holding time than Its sensitivity to temperature is much lower, so purer TiAl alloy powder cannot be obtained simply by extending it for a few hours, so Ti and Al powder after dehydrogenation cannot be fully alloyed in a lower temperature range. Only by heating to a certain temperature to provide sufficient energy for the diffusion of Ti and Al powders can very pure TiAl alloy powders be obtained. At the same time, the price of titanium hydride powder is much cheaper than that of titanium powder obtained by dehydrogenation of titanium hydride, which is far lower than the additional cost caused by heating. Therefore, the present invention has clear practical significance.

The advantages of the present invention are: the conventional production of TiAl intermetallic compound powder is to use titanium powder and aluminum powder as raw materials, and the titanium powder used is obtained by dehydrogenating titanium hydride, so the price is relatively high; the present invention directly uses hydrogenation Titanium powder and aluminum powder are used as raw materials, and sintering is carried out under high vacuum and low temperature. Not only is the cost low, but the obtained TiAl intermetallic compound powder contains few impurities; the process of the above method is extremely simple.

detailed description

Example 1:

Step 1: Weigh 240g of titanium hydride powder with an average particle size of 30μm, and 135g of aluminum powder with an average particle size of 8μm, mix them in a high-energy ball mill for 1 hour, and add toluene as a control agent to prevent oxidation;

Step 2: Heat the mixed powder in a rapid heating tubular electric furnace with a vacuum degree of 3×10 ^-3 Pa. The heating process is as follows: heating to 120°C at a heating rate of 3°C/min, holding at 120°C for 10min, from 120°C to 500°C at a heating rate of 3°C/min, hold for 2 hours, then raise the temperature to 750°C at a heating rate of 6°C/min, and hold for another 2 hours;

Step 3: Cool the heated powder with the furnace, and perform simple grinding to obtain TiAl intermetallic compound powder with an average particle size of 10 μm.

Example 2:

Step 1: Weigh 240 g of titanium hydride powder with an average particle size of 50 μm, and 135 g of aluminum powder with an average particle size of 15 μm, and mix them in a high-energy ball mill for 20 hours, adding toluene as a control agent to prevent oxidation;

Step 2: Heat the mixed powder in a rapid heating tubular electric furnace with a vacuum degree of 3×10 ^-2 Pa. The heating process is as follows: heating to 120°C at a heating rate of 3°C/min, holding at 120°C for 10min, from 120°C to 1000°C at a heating rate of 6°C/min, and then hold at 1000°C for 3 hours;

Step 3: Cool the heated powder with the furnace, and perform simple grinding to obtain TiAl intermetallic compound powder with an average particle size of 30 μm.

Claims (1)

1. a method for preparing TiAl intermetallic compound powder with titanium hydride powder, is characterized in that: 1) Weigh titanium hydride powder and aluminum powder according to the atomic ratio of Ti and Al being 1:1, and ball mill in a high-energy ball mill for 1-24 hours for homogenization; during the process, toluene is added as a control agent to prevent oxidation; The average particle size of titanium hydride powder used as raw material is 20-65 μm, and the average particle size of aluminum powder is 5-20 μm; 2) Put the uniformly mixed materials into a rapid heating tubular electric furnace with a vacuum degree of ≤4.0×10 ^-2 Pa, and perform dehydrogenation treatment at 100-500°C, with a heating rate of 2-4°C/min, and keep warm The time is 10min-4 hours; then directly heated to a high temperature, and kept at 1000°C for 1-5 hours for alloying; the purpose of the low-speed temperature rise diffusion reaction is for the diffusion reaction of aluminum powder and the dehydrogenation of titanium hydride powder, higher temperature Insulation is for alloying between titanium and aluminum; 3) After heating, cool with the furnace and grind to obtain TiAl intermetallic compound powder; The average particle size of the ground TiAl intermetallic compound powder is 10-50 μm.