Phase-field crystal simulation of evolution of liquid pools in grain boundary pre-melting regions  

晶体相场法模拟晶界预熔区液相熔池的演化

作　　者：Xiao-lin TIAN Yu-hong ZHAO Dun-wei PENG Qing-wei GUO Zhen GUO Hua HOU 田晓林;赵宇宏;彭敦维;郭庆伟;郭震;侯华(中北大学材料科学与工程学院,太原030051)

机构地区：[1]School of Materials Science and Engineering,North University of China,Taiyuan 030051,China

出　　处：《Transactions of Nonferrous Metals Society of China》2021年第4期1175-1188,共14页中国有色金属学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (51774254,51774253,51701187,51674226,51804279,51801189);The Science and Technology Major Project of Shanxi Province,China (20191102008);Platform and Talent Project of Shanxi Province,China (201805D211036);Guiding Local Science and Technology Development Projects by the Central Government of China (YDZX20191400002796);Transformation of Scientific and Technological Achievements Special Guide Project of Shanxi Province,China (201804D131039)。

摘　　要：Pre-melting is a phenomenon that below the melting point the liquid-like structure appears at the grainboundary while the grain interior remains a crystal structure. The phase-field crystal method was employed to investigate the early evolution of the liquid pools in pre-melting regions, mainly involving four structural transformations: solid-solid state → small droplet → large liquid pool → homogeneous liquid melting. The microscopic morphology and free energy variation with different average atomic densities demonstrate that the average atomic density is sensitive to the morphological characteristics of liquid pools. Both two-dimensional and three-dimensional simulation results show that the amplitude reduction of order parameters can promote the order-disorder transition of grain boundaries, causing pre-melting in the edge dislocation aggregation. The relationship between the average atomic density and the width of the liquid pools is verified from thermodynamics, which provides a prerequisite for the application of high-temperature strain in the later stage to some extent.预熔是指晶体在低于熔点温度时,晶界处预先出现类似液体而块体仍为晶体状的现象。采用晶体相场法研究原子密度对晶界预熔的影响。结果表明:晶界处液相熔池的早期演化主要涉及4个形态特征:固-固状态→小液滴状态→较大的液相熔池→均质熔融层。通过对比不同平均原子密度下的微观结构和能量变化,表明平均原子密度对液相池的形态特征敏感。二维与三维模拟结果表明,平均原子密度的降低能抑制刃型位错聚集区域中原子的结晶相特征,这有助于液相熔池的形成。从热力学的角度验证平均原子密度与液相熔池宽度之间的关系,在一定程度上为后续施加高温应变提供前提条件。

关 键 词：phase-field crystal method pre-melting edge dislocations liquid pools 

分 类 号：TG113[金属学及工艺—物理冶金]