中文摘要：

研究了Al含量对TiAl合金微观组织及压缩力学性能的影响,并分析其破坏机理。研究发现,Al含量对TiAl合金微观组织影响显著。通过真空自耗电弧冶炼方法制备的Ti-44.1Al（原子分数,%）合金的组织为全层片组织,层片团粗大,呈现柱状晶特征;而Ti-47.3Al合金的组织为双态组织,三维连通的网状γ相将粗大的铸造组织分割成细小的层片团。力学性能研究发现,与Ti-47.3Al合金相比,无论是在准静态还是动态压缩加载条件下,Ti-44.1Al合金都表现出较高的屈服强度,较低的抗压强度以及较差的塑性变形能力。破坏机理分析表明,准静态压缩加载条件下,在Ti-44.1Al合金中,微孔在γ/α2层片团的α2相中萌生并聚集形成裂纹;而在Ti-47.3Al合金中,微孔同时在γ/α2层片团中α2相中以及三维连通的网状γ相中萌生,微孔聚集形成裂纹并扩展;动态压缩加载条件下,在Ti-44.1Al合金中,在γ/α2层片团中存在大量的α2相与γ相的相界,由于加载时间短,在相界处易引起位错塞积而导致应力集中,致使微裂纹在相界处迅速萌生并扩展;而在Ti-47.3Al合金中,微裂纹不仅在γ/α2层片团中α2相与γ相的相界处萌生,同时也会在三维连通的网状γ相中迅速萌生并扩展,直至材料破坏。

英文摘要：

The effects of aluminum content on microstructure and compressive properties of TiA l alloy were investigated, and the failure mechanism was also discussed. It is interesting to find that the content of aluminum remarkably influences the microstructure of TiA l alloys fabricated by Induction Skull Melting technique. The microstructure of Ti-44.1Al（at%, similarly hereinafter） alloy is fully lamellar, and the γ/α_2 lamellar colonies exhibit the characteristics of columnar crystals. The microstructure of Ti-47.3Al alloy is duplex, which contains γ/α2 lamellar colonies and γ phase with 3D net structure. The microstructure of Ti-47.3Al alloy is much finer than that of Ti-44.1Al alloy. Compared with Ti-47.3Al alloy, Ti-44.1Al alloy exhibits higher yield strength, lower ultimate compressive strength, and lower ductility under both quasi-static compression and dynamic compression. Failure analysis after quasi-static compression shows that in Ti-44.1Al alloy, micro-pores initiation occurs in α2 phase of γ/α2 lamellar colonies. In Ti-47.3Al alloy, micro-pores initiation starts in both α2 phase of γ/α2 lamellar colonies and γ phase with 3D net structure. Thus, the failure mechanisms of both Ti-44.1Al alloy and Ti-47.3Al alloy are micro-porous coalescence fracture under quasi-static compression. Failure analysis after dynamic compression shows that in Ti-44.1Al alloy, micro-cracks originate in phase boundary between γ phase and α2 phase. In Ti-47.3Al alloy, micro-cracks originate in both phase boundary of γ/α2 lamellar colonies and γ phase with 3D net structure. With the increasing strain, the micro-cracks propagate rapidly, and cause the failure of the alloys under dynamic compression.