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对热挤压后新型Ti Al合金Ti-46.5Al-3Ta-2Cr-0.2W的微观结构,力学性能及氧化行为进行了研究。结果表明,该合金挤压后微观组织主要由γ和α2相组成近片层组织,其片层晶粒尺寸为50~70μm。通过不同冷却速率获得了等轴,近片层及全片层的结构,尤其是在油淬后的组织中发现了大量的块状相。拉伸试验结果表明,挤压后的合金室温屈服强度和抗拉伸强度分别从807和846 MPa,降至800℃的620和760 MPa,而其伸长率从2.16%提高至3%左右,说明该合金在高温条件下依然具有较高的强度。断口观察表明,与其他合金相比,该合金的裂纹长度较小,而且Ta的添加有利于合金塑性的提高。最后对新型Ti Al基合金在800℃氧化行为进行了讨论,发现Ta的加入可以降低氧在Ti Al合金的溶解度,同时因其本身具有低的扩散率,在升高温度时能抑制Ti O2的生长。
The microstructure, mechanical properties and oxidation behavior of a new TiAl alloy Ti-46.5Al-3Ta-2Cr-0.2W after hot extrusion were investigated. The results show that the microstructure of the alloy is mainly composed of γ and α2 phase near the lamellar structure, the grain size of the lamella is 50 ~ 70μm. Obtained by the cooling rate of the equiaxed, near-slice and whole slice structure, especially in the oil quenched after the organization found a large number of massive phase. Tensile test results show that the yield strength and tensile strength at room temperature of extruded alloy decrease from 807 and 846 MPa to 620 and 760 MPa respectively at 800 ℃, while the elongation increases from 2.16% to 3% This shows that the alloy still has high strength under high temperature conditions. Fracture observation shows that compared with other alloys, the crack length of the alloy is small, and the addition of Ta is conducive to the plasticity of the alloy. Finally, the oxidation behavior of the new TiAl-based alloy at 800 ℃ was discussed. It was found that the addition of Ta can reduce the solubility of oxygen in the TiAl alloy and at the same time, due to its low diffusion rate, Grow.