A Method for Accurately Controlling Metastable Microstructure Stabilization to Realize γ-tial Alloy Refinement

Abstract

The invention discloses a method for accurately controlling the stabilization of the metastable structure to realize the refinement of the γ-TiAl alloy. The γ-TiAl alloy is composed of the following atomic percentages: Al 47.0%-48.5%, Nb 1.0%-2.5%, Cr 0.0% to 2.0%, Ta 1.0% to 3.0%, B 0.01% to 0.1%, and the balance is Ti. The method includes: 1. preparing γ-TiAl alloy ingot; 2. hot isostatic pressing and homogenization treatment; 3. Heating and heat preservation in the α single-phase region and α+γ two-phase region in turn, and repeating the above heat treatment process multiple times; 4. Heating and heat preservation in the α single-phase region to obtain a γ-TiAl alloy with a fine-grained full-lamellar structure. The invention adopts the addition of alloy elements combined with cyclic heat treatment to continuously control the metastable structure, realizes the grain refinement in the γ-TiAl alloy, and improves the properties such as room temperature plasticity and strength of the γ-TiAl alloy.

Description

A method for precise control of metastable microstructure stabilization to achieve γ-TiAl alloy refinement technical field The invention belongs to the manufacture field of lightweight high temperature structural material, be specifically related to a kind of precise control metastable tissue stabilization Methods to achieve γ-TiAl alloy refinement. Background technique At present, the power system of aerospace, automobile engine, petrochemical high-temperature parts, etc. The demand for materials is urgent, because the density of γ-TiAl alloy is only about 50% of that of Ni-based superalloy (about 3.8-4.3g / cm 3 ), and has the advantages of high specific modulus, high creep resistance, good combustion resistance, good oxidation resistance, strong corrosion resistance, etc., has gradually become a Candidate materials for high temperature components to replace superalloys to achieve substantial weight reduction. The second generation of casting γ-TiAl alloy devel...

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Problems solved by technology

However, the existing casting industrial technology makes it difficult to control the grain size of lamellar clusters below 200 μm

The invention patent titled "A Heat Treatment Method for Refinement of TiAl Alloy Full Lamellar Cluster Size" (publication number: CN107904530A) adopts a two-step heat treatment process of quenching and tempering to refine TiAl alloy to obtain 20-100μm Fine-grained full-lamellar structure; however, this method uses a high-energy heat treatment method of quenching, which increases the cracking tendency of the ingot, and the degree of refinement is limited

The invention patent titled "A Multi-step Cyclic Heat Treatment Method for Improving the Mechanical Properties of Traditional Cast γ-TiAl Alloys" (publication number: CN105220096A) heat-treats the homogenized TiAl alloy continuously in the α+γ two-phase region; but the Method implementation takes too long and has limited granularity

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