低层错能的CrCoNi基(中)高熵合金在室温或低温下具有优异的断裂韧性.同时,在冲击条件下变形机理的多样性使CrCoNi基(中)高熵合金具有优异的抗变形能力,有望作为抗冲击结构材料被应用于极端环境中.然而,金属材料"强度-塑性"的倒置关系在CrCoNi基(中)高熵合金中依然存在,低的屈服强度限制了CrCoNi基(中)高熵合金的潜在应用.因此,选择合适的强化方法,提高CrCoNi基(中)高熵合金的屈服强度,同时保持高塑性,成为目前高熵合金研究的热点.本文从固溶元素、晶内缺陷、相结构 3 个方面介绍了目前应用在CrCoNi基(中)高熵合金中的强化方法,从固溶原子、间隙原子、位错、孪晶、相变、梯度结构等多方面讨论了强韧化机制,并以CrCoNi基(中)高熵合金的变形机理为切入点,分析了不同方法对合金性能的提升机理,为低层错能高强韧合金的设计提供了思路.
CrCoNi-based medium-or high-entropy alloys with low stacking fault energy have excellent fracture toughness at room temperature or low temperature.Moreover,under impact conditions,the variety of deformation mechanisms imparts excellent deformation ability to CrCoNi-based medium-or high-entropy alloys,which can be used as impact-resistant structural materials in extreme environments.However,the dilemma of"strength-plasticity"in metallic materials is still observed in CrCoNi-based medium-or high-entropy alloys,and the low yield strength limits the potential application of CrCoNi-based medium-or high-entropy alloys.Therefore,selecting appropriate strengthening methods to improve the yield strength of CrCoNi-based medium-or high-entropy alloys while maintaining their high plasticity has become a hotspot in the research of high-entropy alloys at present.This article introduced the strengthening methods currently applied in CrCoNi-based medium-or high-entropy alloys from three aspects:solid element,lattice defects,and phase structure.Various strengthening and toughening mechanisms,such as solid solution elements,interstitial atoms,dislocations,twinning,phase transformations,and gradient structures,were reviewed.By learning from the deformation mechanisms of CrCoNi-based medium-or high-entropy alloys,the different strengthening mechanisms and their impact on the increase in mechanical properties were analysed,providing ideas for the design of high-strength and high-toughness alloys with low stacking fault energy.