单晶Pt裂纹前端位错行为的原位原子尺度观察

In situ atomic-scale observation of dislocation behaviors at front of crack tip in single-crystal Pt

本文利用原位实验技术,在透射电镜中实现了对高层错能金属单晶铂(Pt)拉伸变形的原位原子尺度观察。研究了单晶Pt裂纹前端的塑性机制。原位原子尺度观察发现,在裂纹扩展的初始阶段,裂纹前端应力较小,此时塑性变形方式主要为60°全位错形核和运动。随着应力的增大,裂纹前端的位错行为不仅是60°全位错的形核、运动以及消失,而且全位错之间会发生反应形成Lomer位错锁。这种裂纹前端的塑性变形方式与其它低层错能金属裂纹前端的塑性行为(偏位错,孪晶)不同。本实验对人们理解金属裂纹前端塑性变形机制,以及层错能对裂纹前端塑性行为的影响具有一定借鉴意义。

In this paper,the atomic-scale tensile deformation process of single-crystal platinum(Pt)with high stacking faults was in-situ observed by using home-made in-situ deformation technique.The plasticity mechanism at front of crack tip of single-crystal Pt was investigated.In situ atomic-scale observations showed that at the early stage of crack tip propagation,the stress values at front of crack tip were relatively low,and the plastic deformation was governed by 60°full dislocation nucleation and motion.As the stress increasing,beside 60°full dislocation nucleation,motion and annihilation,the reaction of two full dislocations that lead to Lomer locks formation were also observed.Our results indicated that the plastic deformation mode at front of crack tip was different from that of the metals with low stacking faults energy(partial dislocations,twinning).These experiment results have shield light on understanding the atomistic deformation mechanism and how stacking faults energy affect their plasticity at front of crack tip of FCC structured metals.