三元Nb系和Ta系硼碳化物稳定性和物理性能的第一性原理研究  

First-principles calculations of stabilities and physical properties of ternary niobium borocarbides and tantalum borocarbides

作　　者：胡前库[1] 秦双红 吴庆华[1] 李丹丹 张斌 袁文凤 王李波[1] 周爱国[1] Hu Qian-Ku;Qin Shuang-Hong;Wu Qing-Hua;Li Dan-Dan;Zhang Bin;Yuan Wen-Feng;Wang Li-Bo;Zhou Ai-Guo(Henan Key Laboratory of Materials on Deep-Earth Engineering,School of Materials Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China)

机构地区：[1]河南理工大学材料科学与工程学院,河南省深地材料科学与技术重点实验室,焦作454000

出　　处：《物理学报》2020年第11期187-196,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51472075,51772077);河南省高校科技创新团队(批准号:19IRTSTHN027);河南省高校基本科研业务费专项资金(批准号:NSFRF180308)资助的课题.

摘　　要：过渡金属轻元素化合物是高硬度材料的潜在候选.以往研究多集中在二元过渡金属硼化物、碳化物和氮化物,三元相的研究则相对较少.本文通过提炼和堆垛已知相Nb3B3C (Ta3B3C)和Nb4B3C2 (Ta4B3C2)的结构基元,构建不同组分的Nb-B-C和Ta-B-C三元相结构模型,采用第一性原理计算方法,计算所建结构的形成焓、声子谱和弹性常数,通过判断其热力学、动力学和力学稳定性,绘出了三元Nb-B-C和Ta-B-C相图,成功预测了5种Nb-B-C和6种Ta-B-C三元稳定相.力学和电学性能计算结果显示Nb-B-C和Ta-B-C三元稳定相均为高硬度导电材料,硬度大约为25 GPa.Transition-metal light-element compounds are potential candidates for hard materials.In the past,most of studies focused on the binary transition metal borides,carbides and nitrides,while the researches of ternary phases are relatively rare.In this paper,the structure units of the known Nb3B3C and Nb4B3C2 phases are first analyzed to be Nb6C octahedron and Nb6B triangular prism,respectively.By stacking the Nb6C octahedron and Nb6B triangular prism,twenty ternary Nb-B-C and twenty ternary Ta-B-C configurations with different compositions are constructed.The chemical formula of these Nb-B-C and Ta-B-C configurations can be defined to be Nb(m+n+2)B(2m+2)Cn and Ta(m+n+2)B(2m+2)Cn,respectively.Using first-principles density functional calculations,thermodynamical,dynamical and mechanical stabilities of the constructed ternary Nb-B-C and Ta-B-C configurations are investigated through calculating their enthalpies of formation,phonon dispersions and elastic constants.Five Nb-B-C(Nb3B3C,Nb4B3C2,Nb6B4C3,Nb7B4C4 and Nb7B6C3)phases and six Ta-B-C(Ta3B3C,Ta4B3C2,Ta6B4C3,Ta7B4C4,Ta7B6C3 and Ta3BC2)phases are predicted to be stable by analyzing the constructed ternary Nb-B-C and Ta-B-C phase diagrams,in which the seven phases(Nb6B4C3,Ta3B3C,Ta4B3C2,Ta6B4C3,Ta7B4C4,Ta7B6C3 and Ta3BC2)are first predicted to be stable.The Nb6B4C3,Ta6B4C3,Ta4B3C2 and Ta3B3C phases are stable when temperature is higher than 1730,210,360 and 1100 K,respectively.And the Ta3BC2 phase is stable only when temperature is lower than 130 K.The calculated results about mechanical and electric properties show that these Nb-B-C and Ta-B-C phases are conductive materials with a high hardness in a range of 23.8–27.4 GPa.

关 键 词：硬质材料 相图 第一性原理计算 稳定性 

分 类 号：TQ163[化学工程—高温制品工业]