Dual-structure titanium aluminum (TiAl) alloy and preparation method thereof

Abstract

The invention discloses a dual-structure titanium aluminum (TiAl) alloy and a preparation method thereof. The atomic percentage of the TiAl alloy compositions is TiaAlb, wherein a is more than 49 and less than 50.6, b is more than 49.4 and less than 51, and a plus b is equal to 100, the main body of the dual-structure TiAl alloy is a columnar crystal, and gamma-phase equiaxed grains are generated at a grain boundary of the columnar crystal; the preparation of the TiAl alloy comprises the following steps: selecting suitable compositions according to the phase diagram of a TiAl binary alloy system; using a water cooled copper crucible and a vacuum non-consumable arc melting furnace to prepare a cylindrical rod master alloy; using an optical floating zone crystal growing apparatus to carry out directional solidification on the master alloy to obtain the dual-structure TiAl alloy. The dual-structure TiAl alloy disclosed by the invention comprises the columnar crystal and an equiaxed grain structure, wherein the equiaxed grain structure is at the grain boundary of the columnar crystal, so that performance characteristics of a columnar crystal structure can be kept, and then performances of the alloy can be simply and effectively improved.

Description

technical field [0001] The invention belongs to the technical field of lightweight high-strength structural materials, and in particular relates to a double-structure TiAl alloy and a preparation method thereof. Background technique [0002] TiAl alloy has the advantages of low density, high specific strength, good high temperature performance and excellent oxidation resistance. It is the best candidate material for aerospace high temperature applications, especially for engines, with grams as the unit of weight reduction. GE Company of the United States successfully used Ti-48Al-2Cr-2Nb (4822) alloy to develop the rear two-stage low-pressure turbine blade of Boeing aircraft, which reduced the weight of a single aircraft engine by about 200Kg. Airbus has used forged TiAl alloy to manufacture PW1100G engine blades, and has successfully tested the flight. In addition, automotive supercharger turbine blades and other components have a large number of application requirements f...

AI Technical Summary

Problems solved by technology

[0003] Although TiAl alloy has significant irreplaceable advantages, its room temperature brittleness makes TiAl alloy difficult to process and limits its further application on high-temperature components.

The preparation of TiAl-based composite materials is an effective method to improve the room temperature brittleness of TiAl alloys, but it generally adopts the method of external compounding, which has prominent interface problems and cannot effectively improve the performance.

For example, Cui Xiping and others used the solid-liquid reaction method to prepare TiAl-based composite plates with layered reinforcements ("Acta Metals", 2013). In fact, this method did not effectively improve the room temperature performance of TiAl alloys. The reason It is hard and brittle TiB 2 enriched layer at the interface caused by

In addition, Chen Guang's research group found that the preparation of columnar or single crystal TiAl alloys by directional solidification can also improve the room temperature plasticity of TiAl alloys (a high-strength and high-plasticity TiAl alloy material and its preparation method, patent application number: 201410529844.5), however, this method The success rate of obtaining TiAl single crystal is relatively low, and it is difficult to be commercially applied

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