γ′-(Ni1-xCox)3Al1-yTiy合金的力学性能的第一原理研究

First-Principles Study on Mechanical Properties of γ′-(Ni1-xCox)3Al1-yTiy Alloys

通过密度泛函理论计算,研究了γ′-(Ni1-xCox)3Al1-yTiy(0<x<1,0.05<y<0.25)合金体系。合金体系的组分无序性采用相干势近似处理。分析合金在任意化学配比下Ti(5-25at.%),Co(0-100at.%)元素对合金力学性能、磁性以及相稳定性的影响。结果表明:随着Ti含量增加,晶格膨胀,弹性常数增大,形成焓降低,使L12结构更加稳定。Al位的Ti组分增加可以提高剪切模量和杨氏模量,Co组分增多会降低二者的数值。计算结果表明Co元素增强合金延展性,Ti元素增强L12相的稳定性。

γ′-(Ni1-xCox)3Al1-yTiy(0<x<1,0.05<y<0.25)alloys were studied by using the density functional theory calculation.The subsitutional disorder of alloys was treated by coherent potential approximation.The effect of Ti and Co elements on the mechanical,magnetic and phase stability of the alloys were analyzed for an arbitrary chemical ratio.The results indicate that Ti can further stabilize the L12 phase,the lattice parameters and elastic moduli increase with the increment of Ti concentration.The Ti atoms occupying Al site increase shear modulus and Young’s modulus,while Co could decrease these two moduli.The results demonstrate that Co improves the ductility of the alloys,while Ti stabilize theγ′phase.