Ni-Cu合金力学和热力学性质第一性原理研究

Investigation on First-principles for Mechanical and Thermodynamic Properties of Ni-Cu Alloy

基于密度泛函理论,采用CASTEP和DMol3程序软件包研究了Ni_xCu_((1-x))(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1)合金的力学性能和热力学性质。计算了合金的弹性常数、体模量(B)、剪切模量(G)、Young's模量(E)、Poisson比(v)、熵(S)、焓(H)、比热容(C)及吉布斯自由能(G)。结果表明:Ni-Cu固溶体都是延性相,Ni_(0.9)Cu_(0.1)抗变形能力、硬度最高,其次是Ni_(0.8)Cu_(0.2),然后是Ni_(0.1)Cu_(0.9)。而延展性和塑性Ni_(0.1)Cu_(0.9)最好,其次是Ni_(0.9)Cu_(0.1),说明Ni_(0.1)Cu_(0.9)、Ni_(0.9)Cu_(0.1)综合力学性能最好。随着温度的升高,Ni_xCu_((1-x))(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1)合金体系的熵和焓都增大;比热容先增大,逐渐趋于一个定值。Gibbs自由能随着温度的升高而降低,表明温度升高,体系的热稳定性增强;且在同一温度下,随着Cu含量的升高,自由能依次减小,热稳定性增强。

Based on the density functional theory, the mechanical properties and thermodynamic properties ofNixCu （1-2）（x= 0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1） alloy were researched by CASTEP and DMol3 software package. The elastic constants, bulk modulus（B）, shear modulus（G）, Young＇s modulus（E）, Poisson ratio（v）, entropy （S）, enthalpy（/-/）, specific heat capacity （C） and Gibbs free energy （G） were calculated. The results show that Ni-Cu alloy are all ductile phase. The resistance to deformation and the hardness of Ni0.9C0.1 is highest, next is N0.8Cu0.2 then Ni0.1Cu0.9 While the ductility and plasticity of Ni^lCu0~ is best, followed by N0.9Cu0.1, which indicate that NialCu09 and N0.9Cu0.1 shows the best comprehensive mechanical properties. With the increase of temperature, the entropy （S） and enthalpy（H） of NLCU（1-x）（x=0,0.1,0.2,0.3,0.4,0.5, 0.6,0.7, 0.8,0.9,1）increase, while specific heat capacity （C） increases first, and then tends to fixed value. The Gibbs free energy decreases with the increase of temperature, that is to say, the thermal stability of the system enhances, as the temperature elevates. At the same temperature, the free energies decrease with the increase of Cu content, that is, the thermal stability enhances.