Directional TiAl-based alloy and preparation method thereof

Abstract

The invention discloses directional TiAl-based alloy and a preparation method thereof. According to the atomic percentage, TiAl alloy components are expressed as Ti-(40-50)Al-aNb-bCr-cMo-dV-eMn, wherein in the formula, a, b, c, d, e are atomic percentages, a+b+c+d+e is less than or equal to 10, and the balance is Ti. The method for preparing the columnar crystal TiAl-based alloy includes the following steps that mother alloy is smelted through vacuum induction suspension, and a mother alloy cast rod is prepared through vacuum suction casting; an optical floating zone crystal growth system is adopted, argon is used as protection gas, the flow speed is 3-3.6L / min, the width of a regional heating zone is 6-6.7mm, heat treatment is performed on the TiAl-based alloy cast rod, the heating temperature is controlled to be 1250-1350 DEG C, the drawing speed is in the range of 3-13 micrometers per second, and the columnar crystal TiAl-based alloy is prepared. Compared with a directional solidification technology, in the preparation method, peritectic reaction is omitted, and therefore peritectic segregation is avoided; the problem that refractory metal and alloy, such as tungsten and molybdenum, with direction tissue cannot be prepared through the direction solidification technology can also be solved.

Description

technical field [0001] The invention relates to an oriented TiAl-based alloy and a preparation method thereof, in particular to a method for preparing a columnar TiAl-based alloy which is energy-saving at a relatively low temperature, has no pollution, and has directional organization, and can be used as an aerospace engine turbine blade Preparation of materials, such as nickel-based superalloys, etc. Background technique [0002] TiAl-based intermetallic compounds have the advantages of low density, high specific strength, high elastic modulus, excellent oxidation resistance and creep resistance, and can maintain high specific strength and specific stiffness at high temperatures. It has broad application prospects in the fields of engine and automobile high temperature resistant structural materials. GE Corporation of the United States recently announced that the two-stage blades behind the low-pressure turbine of the GENX engine used in Boeing 787 and 747-8 civil aviation...

AI Technical Summary

Problems solved by technology

In addition, due to the low symmetry of the crystal structure of intermetallic compounds and the poor binding force of grain boundaries, the more grain boundaries there are, the more harmful they are

Conventional heat treatment processes can be classified into two categories: quenching-tempering / aging heat treatment and cyclic heat treatment, but conventional heat treatment can only obtain fine equiaxed grains, but cannot obtain materials with orientation or columnar crystals

[0004]The existing directional solidification equipment [patent: CN 103436960 A] to prepare TiAl-based alloy not only needs to heat the alloy above the melting point, but also requires high energy consumption, and the heating width of the equipment High, low efficiency, slow growth

Because a crucible is required, it also contaminates the alloy melt

The specific drawbacks of the existing directional solidification technology for preparing TiAl-based alloys [patent: CN 102400074 A] are as follows. First, directional solidification needs to heat the material above the melting point, so energy consumption is high; second, due to titanium and Titanium alloy melt reacts violently with almost all ceramic crucible materials, so it will pollute the alloy; third, the directional solidification process undergoes peritectic reaction, so segregation will occur, which has a great impact on material properties; fourth, directional solidification Solidification technology cannot prepare refractory metals and alloys such as tungsten and molybdenum

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