高纯稀土对M50钢液析碳化物的影响  

Effect of Adding High Purity Rare Earth on Primary Carbide in M50 Steel

作　　者：邓朝辉 陈云[1] 巩桐兆 徐闯 陈星秋[1] 傅排先[1] 李殿中[1] DENG Chaohui;CHEN Yun;GONG Tongzhao;XU Chuang;CHEN Xingqiu;FU Paixian;LI Dianzhong(Shenyang National Laboratory of Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China)

机构地区：[1]中国科学院金属研究所沈阳材料科学国家研究中心,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016

出　　处：《材料研究学报》2023年第12期915-923,共9页Chinese Journal of Materials Research

基　　金：国家重点研发计划(YFB3501503);中国科学院战略性先导科技专项(XDC04040202);国家自然科学基金(52031013);中国博士后科学基金(2021TQ0335)。

摘　　要：研究了在M50钢液中添加La、Ce混合稀土和纯Ce稀土对碳化物析出的影响。结果表明,添加稀土不改变液析碳化物的成分和结构,但是使块状碳化物的尺寸和共晶碳化物的面积减小,高纯Ce稀土的效果更显著。实验和计算结果揭示了在M50钢液中添加稀土影响碳化物析出的机制:加入稀土能变质钢液中的夹杂物,使生成的富含稀土的夹杂物成为高温δ-铁素体和奥氏体的形核剂,促进了高温δ-铁素体和奥氏体的形核和减小二次枝晶臂,阻碍碳化物形成元素在液相中的扩散和碳化物长大。第一性原理分子动力学计算结果表明,残留的游离稀土元素Ce与钢液中的元素原子间的相互作用,能降低熔体中Fe、C的扩散系数和碳化物的生长速率并细化液析碳化物。The large coarsened primary carbides precipitated from melt during solidification is a main factor that impacts the property of M50 bearing steel.In this paper,the effect of adding a relatively large amount of high purity rare earth on the precipitation of primary carbides is studied,including the La-Ce mischmetal and pure Ce.The characterized casting microstructure demonstrated that adding rare earth can effectively reduce and refine the primary carbides,especially for the ingot with addition of only high purity Ce.The mechanism of the effect of rare earth addition on the precipitation of primary carbides is then revealed.On the one hand,the added rare earth modified the traditional inclusions into the com-pound with rare earth,which can be the effective nucleation agent forδ-ferrite and austenite during solidification.And consequently,the dendritic grains and its secondary arm spacing can be refined,which is favor of impeding the diffusion of carbide formation elements in the liquid and then retards the carbide growth.On the other hand,the ab initio molecular dynamics simulations demonstrated that Ce can interact with other elements in the melt and lower the diffusion coefficients of Fe and C,and thus in turn lowers the growth rate of carbide and makes the primary carbides precipitated finer and more dispersive.

关 键 词：金属材料 M50轴承钢 稀土 液析碳化物 第一性原理分子动力学 

分 类 号：TG142.1[一般工业技术—材料科学与工程]