北京工业大学韩晓东团队报道了负焓合金与局部化学有序——导致强度和延展性协同作用的概念和途径。相关研究成果发表在2024年1月18日出版的《国家科学评论》。

固溶在金属和合金中无处不在。局部化学有序化（LCO）是一种发生在许多固溶过程中的基本亚纳米/纳米级过程，可以作为优化强度和延展性的微观结构。然而，LCO的形成尚未完全阐明，更不用说如何为设计LCO提供有效的途径，以实现对卓越强度和延展性的协同作用。

该文中，研究人员提出了负焓合金中LCO的形成和控制。在固溶体中具有工程负焓的情况下，在负焓耐热HEA（RHEAs）中形成遗传LCO组分。与传统的“试错”方法相比，通过RHEAs中的工程负焓控制LCO是有指导意义的，并在环境温度下的张力下产生优异的强度（直到1160MPa）和均匀的延展性（高达24.5%），这是迄今为止报道的最好的方法之一。LCO可以促进位错的交滑移，增强位错之间的相互作用及其在大拉伸应变下的塞积；从而可以获得可持续的应变硬化，以确保合金的高延展性。

该项工作为负焓固溶体和合金的强度和延展性协同作用，以及新功能的新研究领域铺平了道路。

附：英文原文

Title: Negative enthalpy alloys and local chemical ordering: a concept and route leading to synergy of strength and ductility

Author: An, Zibing, Yang, Tao, Shi, Caijuan, Mao, Shengcheng, Wang, Lihua, Li, Ang, Li, Wei, Xue, Xianmeng, Sun, Ming, Bai, Yifan, He, Yapeng, Ren, Fuzeng, Lu, Zhouguang, Yan, Ming, Ren, Yang, Liu, Chain-Tsuan, Zhang, Ze, Han, Xiaodong

Issue&Volume: 2024-01-18

Abstract: Solid solutions are ubiquitous in metals and alloys. Local chemical ordering (LCO) is a fundamental sub-nano/nanoscale process that occurs in many solid solutions and can be used as a microstructure to optimize strength and ductility. However, the formation of LCOs has not been fully elucidated, let alone how to provide efficient routes for designing LCOs to achieve synergistic effects on both superb strength and ductility. Herein, we propose the formation and control of LCO in negative enthalpy alloys. With engineering negative enthalpy in solid solutions, genetic LCO components are formed in negative enthalpy refractory HEAs (RHEAs). In contrast to conventional ‘trial-and-error’ approaches, the control of LCO by engineering negative enthalpy in RHEAs is instructive and results in superior strength (till 1160 MPa) and uniform ductility (up to 24.5%) under tension at ambient temperature, which are among the best reported so far. LCO can promote dislocation cross slip, enhancing the interaction between dislocations and their accumulation at large tensile strains; sustainable strain hardening can thereby be attained to ensure high ductility of the alloy. This work paves the way for new research fields on negative enthalpy solid solutions and alloys for the synergy of strength and ductility as well as new functions.

DOI: 10.1093/nsr/nwae026

Source: https://dx.doi.org/10.1093/nsr/nwae026