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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/α_2层片团的α_2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α_2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/α_2层片团中存在大量的α_2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/α_2层片团中α_2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。
The effect of Al content on the microstructure and compressive mechanical properties of TiAl alloy was studied and the failure mechanism was analyzed. The results show that Al content significantly affects the microstructure of TiAl alloy. The microstructure of Ti-44.1Al (atomic fraction,%) alloy prepared by vacuum consumable arc smelting method is a full-layer structure with large lamella and columnar grain structure. The microstructure of Ti-47.3Al alloy is bistatic Tissue, three-dimensionally connected, network-like γ-phase separates coarse cast tissue into fine lamellar masses. Mechanical properties of Ti-47.1Al alloy found that Ti-44.1Al alloy exhibited higher yield strength, lower compressive strength, and poorer compressive strength than the Ti-47.3Al alloy under both quasi-static and dynamic compression loading conditions Plastic deformation capacity. The analysis of failure mechanism shows that in the Ti-44.1Al alloy, the micropores initiate and aggregate in the α_2 phase of the γ / α_2 lamella in the quasi-static compression loading condition. In the Ti-47.3Al alloy, the micropores At the same time, the micro-pores were aggregated to form cracks in the α_2 phase of γ / α2 lamellae and in the three-dimensionally connected reticular γ phase. In the dynamic compression loading condition, in the Ti-44.1Al alloy, There are a large number of α_2phase and γphase phase boundary in the pellet. Due to the short loading time, the dislocations are easy to cause the stress concentration in the phase boundary, resulting in the rapid initiation and propagation of micro-cracks in the phase boundary. However, In the -47.3Al alloy, microcracks not only initiated at the phase boundary of α_2 phase and γ phase in the γ / α_2 lamella, but also rapidly initiated and expanded in the three-dimensionally connected reticular γ phase until the material was destroyed.