Laves相脆韧变形机制的像差校正电子显微学研究

Laves相是金属间化合物中数量最多的一类结构，广泛存在于含有多种金属元素的合金中，并对合金性能产生重要影响。Laves相在高温下具有优异的力学性能，但低温脆性限制了其应用。因此，对Laves相的变形行为进行研究，进而指导改善其塑性变形能力，对于推动Laves相的实用化进程至关重要。由于结构复杂，当前对Laves相脆、韧变形及其转变的认识还远远不足。本项目拟以C14和C36两种结构的Laves相为研究对象，从低温到高温进行不同温度的显微硬度加载，结合原子分辨率的透射电子显微学表征，系统研究Laves相由低温脆性变形到高温韧性变形条件下的位错运动及其转变过程、微观缺陷结构及其成分的演变。本项目研究有望从原子尺度揭示复杂金属间化合物塑性变形和脆韧转变的机理，为改善复杂结构材料的塑性变形能力，以及该类材料作为合金强化相的成分和结构设计提供理论帮助。

Laves phases form the most abundant class of intermetallic compounds, widely exist in alloys containing several metallic elements and dramatically affect properties of the alloys. Laves phases possess excellent mechanical properties at high temperature, while their severe brittleness at low temperature limits their applications. Therefore, it is crucial to study the deformation behaviors of Laves phases to guide the improvement of their plastic deformation ability, and further to promote the practicalization of Laves phases. Owing to complex structures of Laves phases, the study on their brittle, ductile deformations, and mutual transitions between them, is still in its infancy. This project intends to perform microhardness loading on C14- and C36-type Laves phases from low temperature to high temperature. Combined with atomic-resolution characterizations by transmission electron microscopy, the project will systematically study dislocation motions and their transformation process, microscopic structural and componential evolutions of defects. Mechanisms of plastic deformation and brittle-to-ductile transition in complex intermetallic compounds are to be revealed at atomic scale. The research of the project will provide theoretical guidance for improving the plastic deformation ability of complex structural materials, as well as componential and structural designs of such materials as alloy strengthening phases.