周惠久论坛——Specifics of the Dislocation Motion in BCC Metals and Tribological Contacts

讲座名称: 周惠久论坛——Specifics of the Dislocation Motion in BCC Metals and Tribological Contacts
讲座时间: 2019-05-23
讲座人: Peter Gumbsch
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校区: 兴庆校区
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讲座内容: 讲座时间:2019年5月23日上午10:30 讲座地点:仲英楼 材料学院第一会议室 讲座人:  Prof. Peter Gumbsch   讲座主题:Specifics of the Dislocation Motion in BCC Metals and Tribological Contacts   讲座内容:   Mechanical properties of body-centered cubic (bcc) metals are characterized by several specific aspects like the strong temperature dependence of the flow stress, a brittle-to-ductile transition and a significant tension/compression asymmetry. Most of these specifics can be related to the behavior of screw dislocations in bcc metals but this relation so far is mostly anecdotal and materials specific differences can often not be explained. We are therefore undertaking significant efforts of building a rigorous multiscale modeling framework to describe these properties quantitatively. This is based on an atomistic level understanding of dislocation core structures and energetics. These simulations reveal important details about the influence of non-Schmid (non-glide) stresses on the mobility of screw dislocations which can then be implemented to mesoscopic discrete dislocation dynamics (DDD) simulations. I will report examples where DDD simulations help to understand elementary processes of dislocation interaction and show applications of DDD simulations to studies of plasticity in small-scale bcc single crystals.   As a second topic I will focus on dislocation motion under strong stress gradients as exemplarily found in tribological contacts. Dislocation structures developed in such strong stress gradients include prismatic dislocation structures and a dislocation trace line which constitutes the origin of further microstructural evolution under tribological loading.   I will end with an outlook on the development of continuum models based on advanced 3D dislocation density measures with evolution equations that naturally track dislocation motion.   主办单位: 材料学院 金属材料强度国家重点实验室   
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