报告题目 (Title)：Probing small-scale fracture and plasticity in quasicrystals and high-entropy alloys（准晶和高熵合金的小尺度断裂与塑性的检测）

报告人 (Speaker)：邹宇 教授（多伦多大学）

报告时间 (Time)：2021年11月19日(周五) 10:00

报告地点 (Place)：线上Zoom:

会议 ID：Join Zoom Meeting

https://utoronto.zoom.us/j/2822310747?pwd=SjU2dUpEMXZTWGkxTHRsTWJwZnlRZz09

Meeting ID: 282 231 0747

Passcode: 719584

邀请人(Inviter)：李永乐 副教授

主办部门：理学院物理系

摘要：In the first part of the presentation, we show that typically brittle quasicrystals can exhibit remarkable ductility of over 50% strains and high strengths of ∼4.5 GPa at room temperature and sub-micrometer scales. In contrast to the generally accepted dominant deformation mechanism in quasicrystals—dislocation climb, our observation suggests that dislocation glide may govern plasticity under high-stress and low-temperature conditions. The ability to plastically deform quasicrystals at room temperature should lead to an improved understanding of their deformation and fracture mechanism.

In the second part of the presentation, we present that the fracture properties of high-entropy alloys (HEAs). Most refractory high-entropy alloys (HEAs) are brittle and suffer from limited formability at ambient temperature. Here, using in situ micro-cantilever tests, we show that the fracture toughness of a bi-crystal HEA, Nb25Mo25Ta25W25, is one order of magnitude lower than that of single crystalline ones. In addition, we have documented and described aspects of mud-cracking specific to Cr-containing electrodeposited HEA alloys made from trivalent Cr electrolytes.