L1_2结构γ′-Co_3(Al_(1-x)W_x)相的弹性性质和热力学性质的第一性原理研究  

First-principles Study of Elastic Properties and Thermodynamic Properties of L1_2 Orderedγ′-Co_3(Al_(1-x)W_x)

作　　者：刘兴军[1] 邓斌[1] 许伟伟[2] 韩佳甲[1] 王翠萍[1] LIU Xingjun DENG Bin XU Weiwei HAN Jiajia WANG Cuiping(College of Materials,Xiamen University,Xiamen 361005 ,China School of Aerospace Engineering,Xiamen University,Xiamen 361102,China)

机构地区：[1]厦门大学材料学院,福建厦门361005 [2]厦门大学航空航天学院,福建厦门361102

出　　处：《厦门大学学报（自然科学版）》2017年第2期156-165,共10页Journal of Xiamen University：Natural Science

基　　金：国家国际科技合作专项(2014DFA53040)

摘　　要：采用第一性原理方法并结合准简谐德拜模型,系统研究了W原子分数对Co基高温合金中γ′-Co_3(Al_(1-x)W_x)(x=0,0.25,0.50,0.75,1.0)相的弹性性质和热力学性质的影响.研究发现随W原子分数的升高,γ′-Co_3(Al_(1-x)W_x)相的弹性模量显著提高,而弹性各向异性的程度明显降低,同时γ′-Co_3(Al_(1-x)W_x)相由延性材料向脆性材料过渡转变.通过分析电荷密度和态密度的计算结果,发现随W原子分数的增大,Co和W之间共价键的结合强度呈现增大的趋势,并且Co原子间的电荷密度分布逐渐由各向异性向各向同性过渡转变.在有限温度下,随W原子分数的升高,γ′-Co_3(Al_(1-x)W_x)相的热容、热膨胀系数和焓均减小.The effects of W concentration on the elastic properties, and thermodynamic properties of γ＇-Co3 （All-x Wx ） （x = 0, 0. 25,0.50,0.75,1.0）are investigated using first-principles calculations within generalized gradient approximation （GGA）.It is found that the elastic modulus of γ＇-Coa （Al1-x Wx ）, including bulk modulus, shear modulus and Young＇s modulus, increase with increasing W concentration, while the degree of elastic anisotropy decreases with increasing W concentration.In addition, γ＇-Co3 （All-x Wx ） experiences a ductile-to-brittle transition as the W concentration is increased.By analyzing the charge density distribution and the density of states,it is found that the directional bonding between Co atoms and W atoms becomes stronger with increasing W concentration,and the electron density between Co atoms tends to distribute in a more isotropic manner with increasing W concentration.Moreover,based on the quasi-harmonic Debye-Gruneisen approach, the thermodynamic properties as a function of temperature of γ＇-Co3 （All-x Wx ） （x = 0, 0.25, 0.50, 0.75, 1.0） are calculated, including heat capacities, entropy, enthalpy and thermal expansion coefficients.It was found that heat capacities,enthalpy and thermal expansion coefficient decrease with increasing W concentration.

关 键 词：第一性原理计算 Co基高温合金 弹性性质 热力学性质 

分 类 号：O469[理学—凝聚态物理]