难熔高熵合金:制备方法与性能综述

Refractory high-entropy alloys: A review of preparation methods and properties

  • 摘要: 从加工方法、微观结构以及各类性能三方面介绍了难熔高熵合金(Refractory high-entropy alloys,RHEAs),最后对难熔高熵合金的发展和未来进行了展望。以MoNbTaVW为代表的难熔高熵合金在高温下表现出优于传统镍基高温合金的压缩屈服强度,且屈服强度随温度的变化更加缓慢,高温力学性能优异;以MoNbTaVW、MoNbTaTiZr、HfNbTiZr等为代表的难熔高熵合金,与商用高温合金、难熔金属、难熔合金以及工具钢相比,展现出更优的耐磨性能。以W38Ta36Cr15V11合金为代表的难熔高熵合金在辐照后,除了析出小颗粒第二相外,不存在位错环缺陷结构,抗辐照性能优异。提出了难熔高熵合金未来发展的两大方向:建立高通量的实验和计算方法继续探索更多的难熔高熵合金组成和结构模型;探索多场耦合环境下难熔高熵合金的服役行为。

     

    Abstract: Alloying is one of the main ways to achieve desirable properties in materials. The design concept is based on one or two metal elements, supplemented with multiple trace elements to achieve altered or optimized properties. With the advancement in technology, the traditional alloy has evolved from simple to complex compositions, thus improving their properties and promoting the progress of civilization. High-entropy alloys (HEAs) are a new type of multi-master alloys that are popular in the recent two decades. Unlike conventional alloys, HEAs comprise multiple alloying elements according to the isoatomic or non-isoatomic ratios and have several unique properties, such as high strength and hardness, excellent wear and corrosion resistance, thermal stability, and irradiation resistance. Refractory high-entropy alloys (RHEAs), HEAs made of refractory metals, have attracted great attention because of their excellent high-temperature mechanical properties. This paper discusses RHEAs from three aspects: processing methods, microstructure, and properties. Finally, this work presents the development and future prospects of RHEAs. RHEAs represented by MoNbTaVW alloys show better compressive yield strengths at high temperatures and a slower change of yield strength with temperature than traditional Ni-based high-temperature alloys. Compared with commercial superalloys, refractory metals, refractory alloys, and tool steels, RHEAs, such as MoNbTaVW, MoNbTaTiZr, and HfNbTiZr, show excellent wear resistance. RHEAs represented by W38Ta36Cr15V11 have no dislocation ring defect structure and excellent anti-irradiation performance after irradiation, except for the precipitation of small particles in the second phase. In this paper, two directions of future development of RHEAs were proposed: (1) establishing high-throughput experimental and computational methods to continue exploring composition and structural models of RHEAs and (2) exploring the service behavior of RHEAs in a multi-field coupled environment.

     

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