Microstructure evolution and its effect on high-temperature compressive properties of directionally solidified Ti-44.5Al-3Nb-0.6Si-0.2C alloy by electromagnetic confinement after heat treatment

IF 4.3 2区材料科学 Q2 CHEMISTRY, PHYSICAL

Intermetallics Pub Date : 2024-09-15 DOI:10.1016/j.intermet.2024.108491

Jiajun Zhao, Jun Shen, Shaokai Zheng, Jiaxin Li, Wei Wang, Xiaoyu Gao

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引用次数: 0

Abstract

To regulate the microstructure of directionally solidified TiAl alloy and improve its service temperature and high-temperature mechanical properties, the large-size single crystal Ti-44.5Al-3Nb-0.6Si-0.2C alloy with full lamellar structure prepared by electromagnetic confinement directional solidification was heat-treated in the α single-phase region. The results show that this alloy has high stability and no recrystallization occurs at 1340 °C for 30 min. The (α₂+γ) lamellar structure formed during the subsequent cooling process is consistent with the orientation of the original as-cast state, and the refinement effect is very significant. The thickness of the α₂ and the γ phases is 1/3 and 1/10 of the original structure, respectively. The dislocation strengthening and the interface strengthening are enhanced with the increase of the dislocation density and the number of α₂/γ phase boundaries in the refined lamellar structure after heat treatment, thus resulting in a substantial increase of compressive strength at 1000 °C. The corresponding compressive peak strength at 1000 °C is 2.6 times higher than that of the as-cast alloy, reaching 709 MPa. This exceeds almost all the TiAl alloys under the same conditions reported so far. This research is expected to increase the service temperature of TiAl alloy to 1000 °C, thereby replacing more Ni-based superalloy components and promoting the lightweight development of aero engines.

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热处理后电磁约束定向凝固 Ti-44.5Al-3Nb-0.6Si-0.2C 合金的微观结构演变及其对高温抗压性能的影响

为调节定向凝固 TiAl 合金的微观结构，提高其使用温度和高温力学性能，在 α 单相区对电磁约束定向凝固制备的具有全片状结构的大尺寸单晶 Ti-44.5Al-3Nb-0.6Si-0.2C 合金进行了热处理。结果表明，这种合金具有很高的稳定性，在 1340 ℃ 30 分钟内不会发生再结晶。在随后的冷却过程中形成的（α2+γ）层状结构与原始铸造状态的取向一致，细化效果非常明显。α2和γ相的厚度分别为原始结构的1/3和1/10。随着热处理后细化层状结构中位错密度和α2/γ相界数量的增加，位错强化和界面强化得到加强，从而使 1000 °C 时的抗压强度大幅提高。相应的 1000 °C 抗压峰值强度是铸造合金的 2.6 倍，达到 709 兆帕。这几乎超过了迄今报道的所有相同条件下的 TiAl 合金。这项研究有望将 TiAl 合金的使用温度提高到 1000 °C，从而取代更多的镍基超级合金部件，促进航空发动机的轻量化发展。

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来源期刊

Intermetallics 工程技术-材料科学：综合

CiteScore

7.80

自引率

9.10%

发文量

291

审稿时长

37 days

期刊介绍： This journal is a platform for publishing innovative research and overviews for advancing our understanding of the structure, property, and functionality of complex metallic alloys, including intermetallics, metallic glasses, and high entropy alloys. The journal reports the science and engineering of metallic materials in the following aspects: Theories and experiments which address the relationship between property and structure in all length scales. Physical modeling and numerical simulations which provide a comprehensive understanding of experimental observations. Stimulated methodologies to characterize the structure and chemistry of materials that correlate the properties. Technological applications resulting from the understanding of property-structure relationship in materials. Novel and cutting-edge results warranting rapid communication. The journal also publishes special issues on selected topics and overviews by invitation only.