fcc高熵合金变形机制的中子衍射研究进展

Deformation Behavior and Mechanisms of fcc High-Entropy Alloys: Insights from Neutron Diffraction

摘要:

高熵合金的“多主元”特性，颠覆了传统“单一主元”的合金设计理念，使其具有优异的力学性能。然而，也正因为“多主元”，高熵合金具有复杂的变形行为，表现为多种变形机制交替出现且耦合关联。因此，厘清高熵合金的复杂变形机制是当前研究的难点。在表征复杂变形行为方面，中子衍射技术比传统显微方法更具优势，其强穿透性可原位、实时、无损探测厘米级块体样品在复杂环境下的结构演变，且中子衍射可精确表征C、O等轻元素和近邻元素的晶胞占位。本文从中子衍射原理、实验及数据分析出发，结合当前面心立方高熵合金研究的最新进展，总结并展示了运用中子衍射探究其变形行为的典型范例，揭示了位错、层错、孪晶和相变主导的变形机制。

Abstract:

The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element, endowing them with excellent mechanical properties. However, owing to this multi-principal element nature, high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms. Therefore, elucidating these intricate deformation mechanisms remains a key challenge in current research. Neutron diffraction (ND) techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior. The strong penetration capability of neutrons enables in-situ, real-time, and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments, and ND allows precise characterization of lattice site occupations for light elements, such as C and O, and neighboring elements. This review discussed the principles of ND, experiment procedures, and data analysis. Combining with recent advances in the research about face-centered cubic high-entropy alloy, typical examples of using ND to investigate the deformation behavior were summarized, ultimately revealing deformation mechanisms dominated by dislocations, stacking faults, twinning, and phase transformations.