合金碳化物M_(7)C_(3)的磁性与电子结构  

Magnetism and electronic structure of alloy carbide M_(7)C_(3)

作　　者：王雨[1,2,3] 侯廷平[1,2,3] 林恒福 杨晓萍 吴开明[1,2,3] WANG Yu;HOU Tingping;LIN Hengfu;YANG Xiaoping;WU Kaiming(State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;Hubei Province Key Laboratory of Systems Science in Metallurgical Process,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;Collaborative Innovation Center for Advanced Steels,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions,Hefei 230031,Anhui,China;High Magnetic Field Laboratory,Chinese Academy of Sciences,Hefei 230031,Anhui,China)

机构地区：[1]武汉科技大学省部共建耐火材料与冶金国家重点实验室,湖北武汉430081 [2]武汉科技大学冶金工程过程系统科学湖北省重点实验室,湖北武汉430081 [3]武汉科技大学高性能钢铁材料及其应用省部共建协同创新中心,湖北武汉430081 [4]极端条件下凝聚态物理安徽省重点实验室,安徽合肥230031 [5]中国科学院强磁场中心,安徽合肥230031

出　　处：《钢铁研究学报》2021年第3期240-245,共6页Journal of Iron and Steel Research

基　　金：国家自然科学基金重点资助项目(U1532268);国家自然科学基金青年基金资助项目(11404249);2019年度湖北省高等学校优秀中青年科技创新团队资助项目(T201903);省部共建耐火材料与冶金国家重点实验室2018年度青年基金重点资助项目(2018QN01)。

摘　　要：合金碳化物的析出行为决定了耐热钢在中、高温条件下的服役寿命。利用Diamond软件探索了合金碳化物M_(7)C_(3)(M=Fe,Cr)的晶体结构,并统计了M_(7)C_(3)中原子间的成键情况。同时,利用第一性原理计算其在0 K、0 Pa条件下M_(7)C_(3)中各原子的磁矩和电子结构。结果表明,M_(7)C_(3)中的Fe、C原子沿着〈001〉方向分层排列,且Fe原子沿着〈001〉方向构成了正方形、三角形、六角环;Fe—C键的键长越长,对应Fe原子的磁矩越大;态密度分布显示M_(7)C_(3)的磁矩贡献主要来自于Fe原子的d轨道,Fe原子d轨道与C原子的p轨道发生了杂化,形成了共价键、离子键,且M_(7)C_(3)具有金属性。Cr原子的自旋极化度小于Fe原子,所以Cr原子的加入使得M_(7)C_(3)的磁性减小。此研究有助于拓展碳化物的应用与控制技术,为碳化物的析出强化机制提供了理论基础。The properties of alloy carbides have an important effect on the service life of heat-resistant steels at medium and high temperatures.Diamond software was used to further explore the structure of the alloy carbide M_(7)C_(3)(M=Fe,Cr).The bonding between atoms in M_(7)C_(3) was analyzed statistically.At the same time,the first-principle was utilized to calculate the magnetic moment and electronic structure of alloy carbide M_(7)C_(3) at 0 K and 0 Pa.The results show that the Fe and C atoms in M_(7)C_(3) are layered along the〈001〉,and Fe atoms form square,triangle and hexagon rings along the direction〈001〉.The magnetic moment of corresponding Fe atom increases with length of the Fe-C bond.The density of states indicates that the magnetic moment contribution of M_(7)C_(3) mainly origins from the d orbit of the Fe atom.Covalent bond and ionic band formed due to hybridization of Fe atom and C atom and M_(7)C_(3) is metallic.The spin polarization of Cr atom is smaller than that of Fe atom,so the magnetic properties of M_(7)C_(3) decrease with the addition of Cr atom.This research is helpful to expand the application and control technology of carbides and provides a theoretical basis for the precipitation strengthening mechanism of carbides in heat-resistant steel.

关 键 词：钢 合金碳化物 第一性原理 磁矩 电子结构 

分 类 号：TG154.3[金属学及工艺—热处理]