Abstract The challenge of producing high-density TiAl alloys is hereby addressed by a simple pressureless sintering approach. A systematic study has been made on the effect of Sn addition on the sintering densification, microstructure and mechanical properties of Ti–45Al-8.5Nb-0.2W-0.2B-0.02Y alloy. The results show that Sn addition significantly reduces the alloy's melting point, directly affecting the sintering behavior and with increasing Sn content the optimum sintering temperature decreases. A high-density (≥99.0%) and fine fully lamellar microstructure with a colony size of 40–60 μm can be achieved by a small amount of Sn addition. The lamella has a specific orientation relationship of ( 110 ) γ∥ ( 0001 ) α2 and [ 1 1 ‾ 0 ] γ∥ [ 1 1 ‾ 0 1 ‾ ] α2. Sn element is dissolved in TiAl matrix and the soluble Sn content in α2 phase is almost two times than that in γ phase. Benefitting from the optimized microstructure and Sn solid solution strengthening, the as-sintered TiAl–1Sn alloy exhibits the best mechanical properties, with a compressive strength of 3029 ± 49 MPa, yield strength of 685 ± 57 MPa and strain to failure of 32.5 ± 0.49%, respectively. The optimal Sn content should be between 1 and 2 at.% and beyond this the samples fails prematurely.

中文翻译：

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无压烧结Sn掺杂高Nb TiAl合金的烧结致密化、显微组织和力学性能

摘要 在此通过简单的无压烧结方法解决了生产高密度 TiAl 合金的挑战。系统研究了Sn添加对Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y合金烧结致密化、组织和力学性能的影响。结果表明，Sn的添加显着降低了合金的熔点，直接影响了烧结行为，随着Sn含量的增加，最佳烧结温度降低。通过少量的锡添加可以实现高密度（≥99.0%）和精细的全层状微观结构，集落尺寸为 40-60 μm。薄片具有 ( 110 ) γ∥ ( 0001 ) α2 和 [ 1 1 ‾ 0 ] γ∥ [ 1 1 ‾ 0 1 ‾ ] α2 的特定取向关系。Sn元素溶解在TiAl基体中，α2相中可溶Sn含量几乎是γ相中的两倍。得益于优化的微观结构和 Sn 固溶强化，烧结态 TiAl-1Sn 合金表现出最佳的机械性能，抗压强度为 3029 ± 49 MPa，屈服强度为 685 ± 57 MPa，断裂应变为 32.5 ± 0.49 ％， 分别。最佳 Sn 含量应介于 1 和 2 at.% 之间，超出此范围样品会过早失效。