纳米晶合金热稳定性的熵调控设计

Design for Thermal Stability of Nanocrystalline Alloys Based on High-Entropy Effects

具有纳米尺度晶粒的纳米晶合金由于具有高强度和高硬度而成为材料领域的关注热点,然而,由于晶界占比高,纳米晶合金的热稳定性差,严重制约了在高温甚至室温下的应用。近年来,纳米晶高熵合金由于显著的高熵效应而展现出特殊性能,这一效应同时能在一定程度上缓解纳米晶在较高温度下的低热稳定性问题。本文通过对纳米晶合金常用的热稳定策略和相关研究进展的分析与归纳,探讨从熵调控的角度利用多组元的高熵效应设计的具有高热稳定性的纳米晶高熵合金的稳定机理和力学性能。已有研究结果表明,纳米晶高熵合金有望拓宽纳米晶合金的领域,同时可为突破纳米晶合金低热稳定性瓶颈提供新的思路。

Nanocrystalline alloys(NAs)with nano-sized fine grains and high density of grain boundaries exhibit promising properties,such as high strength and hardness.However,industrial applications of NAs at high or even room temperature have been limited,owing to their thermal instability,which originates from the high proportion of grain boundaries in NAs.Recently,nanocrystalline high-entropy alloys(NC-HEAs)have emerged and have been rapidly developed,which are expected to alleviate thermal instability.In this study,design strategies for the thermal stability of NC-HEAs and related progress are investigated and summarized.In addition,the underlying mechanism for the high thermal stability of NC-HEAs is discussed by utilizing high-entropy effects,based on entropy engineering.These high-entropy design strategies may provide a new methodology for dramatically increasing the thermal stability of NAs.