Al_(2)O_(3)对铝熔体中杂质Fe扩散行为影响的分子动力学模拟  

Molecular dynamics simulation of effect of Al_(2)O_(3)on diffusion behavior of Fe impurity in aluminum melt

作　　者：宋莉莉[1,3] 傅高升 许乾[1] 陈鸿玲 王火生 SONG Li-li;FU Gao-sheng;XU Qian;CHEN Hong-ling;WANG Huo-sheng(School of Materials Science and Engineering,Fuzhou University,Fuzhou 350108,China;College of Physics and Electronic Information Engineering,Minjiang University,Fuzhou 350108,China;School of New Energy and Intelligent Manufacturing,Ningde Vocational and Technical College,Fu’an 355000,China;School of Materials Science and Engineering,Fujian University of Technology,Fuzhou 350118,China)

机构地区：[1]福州大学材料科学与工程学院,福州350108 [2]闽江学院物理与电子信息工程学院,福州350108 [3]宁德职业技术学院新能源与智能制造学院,福安355000 [4]福建工程学院材料科学与工程学院,福州350118

出　　处：《中国有色金属学报》2023年第7期2071-2080,共10页The Chinese Journal of Nonferrous Metals

基　　金：福建省自然科学基金资助项目(2017J01156);福建省科技计划(产学研联合创新)项目(2020Y4018)。

摘　　要：采用分子动力学模拟方法从均方位移、自扩散系数、径向分布函数、配位数等方面分析研究了Al_(2)O_(3)对铝熔体中杂质Fe扩散行为的影响规律。结果表明:Al_(2)O_(3)是影响铝熔体中杂质Fe扩散和富集的关键因素,随着Al_(2)O_(3)含量的增加,杂质Fe的均方位移随之下降,且随着时间的延长,均方位移的增加幅度减小,扩散系数从0.173×10^(−8)m^(2)/s下降到0.037×10^(−8)m^(2)/s,即Al_(2)O_(3)含量的增加阻碍了杂质Fe的扩散,且Al2O3含量阻碍杂质Fe扩散行为的倾向随着时间的延长而加剧。同时,随Al_(2)O_(3)含量的增加,径向分布函数曲线发生明显变化,曲线第一峰的高度逐渐变高,即Fe原子配位数逐渐增加,杂质Fe的聚集程度增加。分析认为Al_(2)O_(3)的存在破坏了铝熔体中原子的有序排布,改变了Fe原子的晶格畸变能和熔体的黏度,造成杂质Fe的扩散困难;Al_(2)O_(3)有利于杂质Fe的富集,为富Fe相的形成创造了有利条件。杂质Fe在铝合金组织中常以富Fe相依附于Al_(2)O_(3)周围,Al_(2)O_(3)可作为异质基底促进富Fe相的形核和生长;杂质Fe的存在形态与Al_(2)O_(3)含量有直接关系,Al_(2)O_(3)含量的减少有利于降低杂质Fe在铝熔体中的富集倾向,从而降低形成团聚的粗大富Fe相的可能性。这与分子动力学模拟结果相吻合,也说明模拟方法是可行的。The effect of Al_(2)O_(3)on the diffusion behavior of Fe impurity in aluminum melts was analyzed by molecular dynamics simulation methods in terms of mean square displacement(DMS),self-diffusion coefficient(D),radial distribution function(g(r))and coordination number(Nij).The simulation results show that Al_(2)O_(3)is the key factor affecting the diffusion and enrichment of Fe.With the increase of Al_(2)O_(3)content,the DMS of Fe decreases and this trend increases as the time prolongs,resulting in a decrease of the diffusion coefficient from 0.173×10^(−8)m^(2)/s to 0.037×10^(−8)m^(2)/s.Therefore,Al_(2)O_(3)in aluminum melt hinders the diffusion of Fe,and the tendency increases with the extension of time.Meanwhile,with the increase of Al2O3 content,the g(r)curve changes significantly,the height of the first peak of the curve gradually becomes higher and the Nij of Fe atoms increases,finally results in the enrichment of Fe.The analysis shows that Al_(2)O_(3)destroys the ordered arrangement of atoms in aluminum melt,changes the distortion energy of Fe and the viscosity of melt,leading to the decline in diffusion capacity and enrichment intensification in enrichment of Fe,which creates favorable conditions for the formation of Fe-rich phase.The Fe impurity often exists around Al_(2)O_(3)in the form of Fe-rich phase,further confirming that Al_(2)O_(3)can be used as a heterogeneous substrate to promote the nucleation and growth of Fe-rich phase.To sum up,Fe impurity is directly related to the Al_(2)O_(3)content,the decrease of Al_(2)O_(3)content is beneficial to reduce the enrichment tendency of Fe and reduces the forming possibility of Fe-rich phase.This is consistent with the results of molecular dynamics simulation,which shows that the simulation method is feasible.

关 键 词：铝熔体 Al_(2)O_(3) 杂质Fe 扩散行为 分子动力学模拟 

分 类 号：TG146.21[一般工业技术—材料科学与工程]