Ti_3(Sn_xAl_(1-x))C_2固溶体电学、力学和热学性能的理论研究  

Theoretical studies of electronic, mechanical and thermal properties of Ti_3(Sn_xAl_(1-x))C_2 solid solutions

作　　者：王雪飞[1] 马静婕[2] 焦照勇[1] 张现周[1] 

机构地区：[1]河南师范大学物理与材料科学学院,新乡453007 [2]河南质量工程职业学院,平顶山467000

出　　处：《物理学报》2016年第20期203-211,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11347004);河南省教育厅自然科学研究计划(批准号:14B140007)资助的课题~~

摘　　要：本文采用基于密度泛函理论的第一性原理平面波超软赝势方法对Ti_3(Sn_xAl_(1-x))C_2(x=0,0.25,0.5,0.75,1)固溶体的晶格结构、结构稳定性、电子结构、力学和热学性质进行了系统的理论研究.研究结果表明:Ti_3(Sn_xAl_(1-x))C_2固溶体具有金属性,都是热力学和力学稳定的脆性材料;Sn原子掺杂能在一定程度上提高材料的力学性能,当Sn原子掺杂浓度为0.75时有最大的体积模量,而掺杂浓度为0.5时有最大剪切模量.此外,Ti_3(Sn_xAl_(1-x))C_2固溶体都具有较高的熔点和德拜温度,其中Ti_3AlC_2,Ti3(Sn_(0.25)Al_(0.75))C_2和Ti3(Sn_(0.5)Al_(0.5))C_2在室温下的晶格热导率均能达到40 W/(m·K)以上,是良好的导热性材料.Available experimental and theoretical studies demonstrate that Ti3AlC2 and Ti3SnC2 compounds exhibit excellent mechanical properties at high temperatures, and thus are rendered a promising candidate of high-temperature structural materials. However, these compounds each have a relatively low hardness, Young＇s modulus, and poor oxidation resistance compared with other MAX phases. In order to overcome these limits, solid solutions on the M, A and/or X sites of the MAX phase compound are considered as a promising strategy to further improve the mechanical properties.Very recently, the solid solutions of Ti3（SnxAl1-x）C2 have been synthesized. However, no theoretical work has focused on the Ti3（SnxAl1-x）C2 solid solutions so far. Therefore, in this work, we perform first-principles calculation to study the microstructures, phase stabilities, electronic, mechanical and thermal properties of Ti3（SnxAl1-x）C2 solid solutions.Particularly, the effects of Sn concentration（x） on the properties are discussed for the Ti3（SnxAl1-x）C2 solid solutions by varying x from 0 to 1.0 in steps of 0.25. All the present ab initio calculations are carried out based on density-functional theory method as implemented in the Cambridge Serial Total Energy Package（CASTEP） code. The electron-ion interaction is described by Vanderbilt-type ultrasoft pseudo-potential with an exchange-correlation function in the generalized gradient approximation（GGA-PW91）. The equilibrium crystal structure is fully optimized by independently modifying lattice parameters and internal atomic coordinates, and we employ the Broyden-Fletcher-Goldfarb-Shanno minimization scheme to minimize the total energy and inter-atomic forces. For the reciprocal-space integration, a Monkhorst-Pack grid of 16 × 16 × 4 is used to sample the Brillouin-zones for Ti3AlC2 and Ti3SnC2 compound, and 8 × 8 × 2 for 2 × 2 × 1 supercell Ti3（SnxAl1-x）C2（x = 0.25–0.75） compounds. The present calculated results of the enthalpy formation energy and mec

关 键 词：Ti3(SnxAl1-x)C2固溶体 力学性质 热学性质 第一性原理计算 

分 类 号：O482[理学—固体物理]