Zuo Zhenbo, Hu Rui, Wang Qingxiang, Gao Zitong, Luo Xian, Lai Yunjin, Xue Sa, Xiang Min, Zhao Xiaohao, Li Shaoqiang
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China.
Sino-Euro Materials Technologies of Xi'an Co., Ltd., Xi'an 710018, China.
Materials (Basel). 2024 Feb 7;17(4):794. doi: 10.3390/ma17040794.
Research on how thermal exposure affects the microstructure and mechanical properties of the Ti-48Al-3Nb-1.5Ta (at. %) alloy, which is prepared via powder hot isostatic pressing (P-HIP), is essential since this low-density alloy shows promise for use in high-temperature applications, particularly for aero-engines, which require long-term stable service. In this study, a P-HIP Ti-48Al-3Nb-1.5Ta (at. %) alloy was exposed to high temperatures for long durations. The phase, microstructure and mechanical properties of the P-HIP Ti-48Al-3Nb-1.5Ta alloy after thermal exposure under different conditions were analyzed using XRD, SEM, EBSD, EPMA, TEM, nanomechanical testing and tensile testing. The surface scale is composed of oxides and nitrides, primarily AlO, TiO, and TiN, among which AlO is preferentially generated and then covered by rapidly growing TiO as the thermal exposure duration increases. The nitrides appear later than the oxides and exist between the oxides and the substrate. With increasing exposure temperature and duration, the surface scale becomes more continuous, TiO particles grow larger, and the oxide layer thickens or even falls off. The addition of Ta and Nb can improve the oxidation resistance because Ta and Nb replace Ti in the rutile lattice and weaken O diffusion. Compared with the P-HIP Ti-48Al-3Nb-1.5Ta alloy, after thermal exposure, the grain size does not increase significantly, and the γ phase increases slightly (by less than 3%) with the decomposition of the α phase. With increasing thermal exposure duration, the γ phase exhibits discontinuous coarsening (DC). Compared with the P-HIP Ti-48Al-3Nb-1.5Ta alloy, the hardness increases by about 2 GPa, the tensile strength increases by more than 50 MPa, and the fracture strain decreases by about 0.1% after thermal exposure. When the depth extends from the edge of the thermally exposed specimens, the hardness decreases overall.
研究热暴露如何影响通过粉末热等静压（P-HIP）制备的Ti-48Al-3Nb-1.5Ta（原子百分比）合金的微观结构和力学性能至关重要，因为这种低密度合金在高温应用中显示出应用前景，特别是对于需要长期稳定运行的航空发动机。在本研究中，对一种P-HIP Ti-48Al-3Nb-1.5Ta（原子百分比）合金进行了长时间的高温暴露。使用XRD、SEM、EBSD、EPMA、TEM、纳米力学测试和拉伸测试分析了不同条件下热暴露后的P-HIP Ti-48Al-3Nb-1.5Ta合金的相、微观结构和力学性能。表面氧化皮由氧化物和氮化物组成，主要是AlO、TiO和TiN，随着热暴露时间的增加，其中AlO优先生成，然后被快速生长的TiO覆盖。氮化物比氧化物出现得晚，存在于氧化物和基体之间。随着暴露温度和时间的增加，表面氧化皮变得更加连续，TiO颗粒变大，氧化层增厚甚至脱落。添加Ta和Nb可以提高抗氧化性，因为Ta和Nb在金红石晶格中取代Ti并削弱O扩散。与P-HIP Ti-48Al-3Nb-1.5Ta合金相比，热暴露后晶粒尺寸没有显著增加，并且随着α相的分解，γ相略有增加（小于3%）。随着热暴露时间的增加，γ相表现出不连续粗化（DC）。与P-HIP Ti-48Al-3Nb-1.5Ta合金相比，热暴露后硬度增加约2 GPa，抗拉强度增加超过50 MPa，断裂应变降低约0.1%。当深度从热暴露试样的边缘延伸时，硬度总体上降低。
