【摘要】 采用基于密度泛函理论的CASTEP程序包,计算了Mg-Al-Sn-Y合金中Mg₁₇Al₁₂,Mg₂Sn和Al₂Y相的结构稳定性、电子结构和弹性性能等。合金形成热△H和结合能E_coh的计算结果表明,Al₂Y相具有最强的合金化能力与体系结构稳定性。电子结构的分析结果解释了这3种金属间化合物的结构稳定性机制和脆性本质。计算出了Mg₁₇Al₁₂,Mg₂Sn和Al₂Y三相的3个独立的弹性常数,并进一步得出了体模量、剪切模量、杨氏模量、泊松比等。分析表明Mg₁₇Al₁₂,Mg₂Sn和Al₂Y三相均为脆性相,其中Al₂Y最脆且最硬。更多还原

【Abstract】 The structural stability,electronic structures and elastic properties of Mg₁₇Al₁₂,Mg₂Sn and A1₂Y phases in Mg-Al-Sn-Y alloy have been investigated by CASTEP program based on the density functional theory.The calculated results of heats of formation and cohesive energies show that Al₂Y phase has the strongest alloying ability and structural stability.The structural stability mechanism and the brittle behavior were obtained from the electronic structure of these three intermetallic compounds.The three independent crystal elastic constants of Mg₁₇Al₁₂,Mg₂Sn and Al₂Y phases were calculated;bulk modulus,shear modulus,Young’s modulus,and Poisson’s ratio were predicted.Further analysis shows that Mg₁₇Al₁₂,Mg₂Sn and Al₂Y phases are all brittle phases,and Al₂Y are the brittlest and stiffest.更多还原