选区激光熔化Ni40Co18Cr18Fe14Al5Ti5高熵合金低温力学性能研究

Cryogenic Mechanical Properties of Ni40Co18Cr18Fe14Al5Ti5 High-Entropy Alloy Fabricated by Selective Laser Melting

摘要:

增材制造技术为高熵合金复杂结构的成形与微观组织的精准调控提供了全新途径，极大拓展了其在航空航天、深空探测等极端服役环境下的应用前景。然而，目前关于增材制造高熵合金在低温条件下的力学行为，特别是动态冲击响应及其微观变形机制，仍然缺乏系统深入的认识。本工作采用选区激光熔化技术制备了Ni₄₀Co₁₈Cr₁₈Fe₁₄Al₅Ti₅高熵合金，系统研究了其在77 K低温环境下的静态拉伸与动态冲击力学行为。研究结果表明，该高熵合金在低温下表现出优异的强塑性匹配与冲击韧性，其屈服强度达1083.4 MPa，均匀延伸率为29.8%，冲击功高达117.7 J。微观结构分析表明，低温变形时高密度位错、层错及其与初始胞结构间的交互作用，有效促进能量耗散，从而赋予该高熵合金优异的低温冲击韧性。

Abstract:

Additive manufacturing technique provides a new approach for the fabrication of complex structures and precise control of the microstructure in high-entropy alloys (HEAs), greatly expanding their application prospects in extreme service environments such as aerospace and deep-space exploration. However, there is still a lack of systematic and in-depth understanding of the mechanical behavior of additively manufactured HEAs under cryogenic conditions, particularly regarding their dynamic impact response and underlying microstructural deformation mechanisms. In this study, a Ni₄₀Co₁₈Cr₁₈Fe₁₄Al₅Ti₅ HEA was prepared using selective laser melting (SLM), and its static tensile and dynamic impact mechanical behaviours at 77 K were investigated. The results show that this HEA exhibits excellent strength-ductility synergy and impact toughness at cryogenic temperature, with a yield strength of 1083.4 MPa, a uniform elongation of 29.8%, and an impact energy as high as 117.7 J. Microstructural analysis reveals that the high-density dislocations, stacking faults, and their interactions between the initial cellular structures during cryogenic deformation effectively facilitate energy dissipation, thereby endowing this HEA with excellent cryogenic impact toughness.