Heat-crack-resistant medium-niobium cast TiAl alloy with over-peritectic solidification characteristic

Abstract

The invention relates to a heat-crack-resistant medium-niobium cast TiAl alloy with over-peritectic solidification characteristic. A medium amount of niobium element is added into a titanium-aluminum alloy with the aluminum content of 48.29-48.4 at.%, and the solidification path is over-peritectic solidification. The casting structure is an over-peritectic solidification structure which forms spherical alpha-dendrites with unobvious differentiation; no over-peritectic solidification structure with obvious peritectic corona, unobvious dendrites and unobvious dendritic segregation exists among the alpha-dendrites, thereby lowering the heat crack tendency of the niobium-containing cast titanium-aluminum alloy cast ingots and castings; and proper amounts of N and B elements are added, so that the solidification structure of the alloy is fine and uniform, thereby further lowering the crack among the lamella groups in the material. The invention provides an ideal cast titanium-aluminum alloy for titanium-aluminum alloy cast ingots and castings, which has the advantages of compact manufacturing structure, less segregation, favorable heat crack resistance and favorable properties; and the alloy can be used for manufacturing cast low-pressure turbine blades, compressor turbine blades and other heat-resistant structure components for engines.

Description

technical field [0001] The invention relates to the field of high-temperature structural materials, and is a cast titanium-aluminum (TiAl) alloy suitable for light-weight high-temperature structures with good thermal crack resistance. technical background [0002] γ-TiAl alloy has the advantages of low density, high specific strength and specific elastic modulus, good oxidation resistance and creep resistance, etc., making it an ideal material for manufacturing high-pressure compressor blades, low-pressure turbine blades, and automobile blades for advanced aircraft engines with high thrust-to-weight ratio. The most competitive material for lightweight heat-resistant structural parts such as turbochargers. [0003] From the first generation TiAl-based alloy (Ti-48Al-1V(at.%)) to the second generation TiAl-based alloy (Ti-48Al-2Nb-2Cr(at.%)), to the third generation TiAl-based alloy ( K5) Until the high-temperature TiAl-based alloys that will serve at 800–900 °C in the future...

AI Technical Summary

Problems solved by technology

[0007] In order to overcome the deficiencies in the existing technology that cannot meet the service temperature of the low-pressure turbine blades of the future engine and the tendency of hot cracking is serious, and cracking is easy to occur, the present invention proposes a hot-cracking-resistant medium-niobium cast TiAl with the characteristics of hyperperitectic solidification alloy

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