大规模并行原子模拟在钛合金界面行为研究中的应用  

Implementing Large-Scale Parallel Atomistic Simulations in the Investigation of Interfacial Behaviors in Titanium Alloys

作　　者：王皞[1] 徐东生[1] 杨锐[1] 

机构地区：[1]中国科学院金属研究所,辽宁沈阳110016

出　　处：《科研信息化技术与应用》2013年第5期35-41,共7页E-science Technology & Application

基　　金：国家重点基础研究发展计划(973计划)(2011CB606404);国家自然科学基金(51171195;51101158)

摘　　要：界面对钛合金的力学性能有至关重要的影响。界面行为的原子模拟涉及的原子数目庞大,必须借助大规模并行计算。本研究组开发了大规模并行分子动力学程序,并将其应用于钛合金中不同种类界面行为的模拟研究。本文以钛铝金属间化合物中的孪晶界和α钛中的特殊大角晶界为例,介绍研究组在钛合金晶界行为的计算模拟方面的近期研究成果。所模拟的体系尺寸达到微米级,所需CPU核数几十至几百不等。研究发现,钛铝模拟晶胞沿伪孪晶方向剪切变形时,等静压力下可产生L11结构的伪孪晶形核长大,而等静张力下剪切可产生真孪晶的形核长大,提出钛铝中一种新的孪晶长大机制。在α钛中,特定取向的两个晶粒所形成的晶界与位错发生相互作用,裂纹形核依赖于加载外力的取向而发生在晶界处或硬取向晶粒内,从而可能导致疲劳断裂行为与加载取向相关。这些结果有助于理解钛合金的塑性变形行为,并为更高尺度的模拟研究提供了原子尺度细节。The mechanical behavior of titanium alloys is often influenced significantly by interfaces. The atomistic investigation of interfaces corresponds with large numbers of atoms, hence requiring large-scale parallel simulations. A molecular dynamics code for such simulations is developed in our group, and used in theinvestigations of interfacial behaviors in titanium alloys. The present paper introduces our recent works on the simulations of interfacial behaviors in titanium alloys, with the coherent twin boundary in TiA1 and a special large-angle grain boundary in a-titanium as two examples. The size of the simulated cells is around micrometers, using tens to hundreds of CPU cores. It is found that, in TiA1 under shear along the pseudo- twin direction, pseudO-twin and true twin nucleates and grows under hydrostatic compression and tension respectively. In α-Ti, the grain boundary between two grains with special orientations interacts with incoming dislocations, and depending on the orientation of the external loading, crack may nucleate either at the grain boundary or in the hard grain, thus it may cause the dependence of fracture on the orientation of external loading. These results contribute to understanding the plastic behavior of titanium alloys and provide atomic details for higher-scale simulations.

关 键 词：并行计算 原子模拟 钛合金 界面 

分 类 号：TG146.23[一般工业技术—材料科学与工程]