Understanding ductile-to-brittle transition of metallic glasses from shear transformation zone dilatation  

作　　者：M.Q.Jiang G.Wilde F.Jiang L.H.Dai 

机构地区：[1]State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences [2]Institute of Materials Physics, Westf?lische Wilhelms-Universit?t Münster [3]State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University

出　　处：《Theoretical & Applied Mechanics Letters》2015年第5期200-204,共5页力学快报（英文版）

基　　金：supported by the National Nature Science Foundation of China (Grant Nos.11522221,11372315,11472287,and 51171138);the National Basic Research Program of China (Grant No.2012CB937500);the CAS/SAFEA International Partnership Program for Creative Research Teams;partially also by DFG

摘　　要：A theoretical model that takes into account the flee-volume aided cooperative shearing of shear transformation zones （STZs） is developed to quantitatively understand the ductile-to-brittle transition （DBT） of metallic glasses. The STZ dilatational strain is defined as the ratio of STZ-activated free volume to STZ volume itself. The model demonstrates that the STZ dilatational strain will increase drastically and exceed the characteristic shear strain of STZ as temperature decreases below a critical value. This critical temperature is in good agreement with the experimentally measured DBT temperature. Our results suggest that the DBT of metallic glasses is underpinned by the transition of atomic-cluster motions from STZ-tvpe rearrangements to dilatational processes （termed tension transformation zones （TrZs））.A theoretical model that takes into account the flee-volume aided cooperative shearing of shear transformation zones （STZs） is developed to quantitatively understand the ductile-to-brittle transition （DBT） of metallic glasses. The STZ dilatational strain is defined as the ratio of STZ-activated free volume to STZ volume itself. The model demonstrates that the STZ dilatational strain will increase drastically and exceed the characteristic shear strain of STZ as temperature decreases below a critical value. This critical temperature is in good agreement with the experimentally measured DBT temperature. Our results suggest that the DBT of metallic glasses is underpinned by the transition of atomic-cluster motions from STZ-tvpe rearrangements to dilatational processes （termed tension transformation zones （TrZs））.

关 键 词：Ductile-to-brittle transitionMetallic glassFractureShear transformation zoneTension transformation zone 

分 类 号：O346.1[理学—固体力学]