| [Experimental Nanomechanics ] In-situ TEM Observation and Atomistic simulation of pyramidal dislocations in c-axis compression of single crystal magnesium In-situ TEM Observation and Atomistic simulation of pyramidal dislocations in c-axis compression of single crystal magnesium Boyu Liu1; Fei Liu1; Bin Li2; Jian-feng Nie3; Zhiwei Shan1; 1XI'AN JIAOTONG UNIVERSITY, Xi'an, China; 2UNIVERSITY OF NEVADA, RENO, RENO, United States; 3MONASH UNIVERSITY, Melbourne, Australia; PAPER: 79/Multiscale/Regular (Oral) SCHEDULED: 14:50/Tue. 29 Nov. 2022/Similan 1 ABSTRACT: <p>Pyramidal dislocations are important dislocations that are able to accommodate the c-axis strain when a single crystal magnesium is compressed along its c-axis. Generally, pyramidal dislocations require higher stresses to activate than basal and prismatic slip systems. But the nature of these dislocations, which have very large Burgers vectors (0.612 nm), has been controversial in terms of slip plane, dislocation dissociation, and dislocation mobility. In this work, we present in-situ TEM observation of pyramidal dislocations in submicron single crystal magnesium during c-axis compression. High density pyramidal dislocations were observed, which generated a large plastic strain, in stark contrast to bulk samples. Computational tomography was conducted to analyze the slip plane of the pyramidal dislocations. The results show that both pyramidal-I and pyramidal-II dislocations were activated. Atomistic simulations were also performed and the simulation results were consistent with the in-situ TEM observations.</p> |
