Al-Cu-Mg-Ag合金强化相价电子结构与热稳定性

Relationships between the Valence Electron Structures of Precipitated Phases and Heat Stability of Al-Cu-Mg-Ag Alloys

基于固体与分子经验电子理论,计算了Al-Cu-Mg-Ag合金中Ω、S与θ′相的价电子结构,用强化相最强共价键的共价电子对数nA分析并研究了Ω、S、θ′相与合金热稳定性的关系。结果表明,Ω、S与θ′相最强键共价电子对数nA分别为0.6591、0.5626、0.4917;Ω、S与θ′相最强键均远强于合金基体α-Al相的最强键,这是Al-Cu-Mg-Ag合金第二相强化的微观本质;Ω相耐热性高于θ′相与S相的原因在于Ω相原子所成共价键键强优于θ′与S相的共价键键强,这也是为获得具有良好高温性能的Al-Cu-Mg-Ag合金应尽量抑制θ′、S相形核,促进Ω相形核的原因。

Based on the empirical electron theory of solids and molecules, the valence electron structures ofΩ,S and θ＇ in Al-Cu-Mg-Ag alloys were calculated, and the relationship between the phases of 19, S with θ＇ and heat stability was analyzed with the help of the covalence electron pairs nA of the strongest covalence bond. It is shown that the value of nA of 19,S and θ＇ is 0. 659 1, 0. 562 6 and 0. 491 7, respectively, which is far bigger than that of the matrix a-Al and responsible for the second phase strengthe- ning. The heat stability of 19 is higher than that of S and θ＇ , which is attributed to the higher covalence bond strength of 19 than that of S and θ＇, so the nucleation of S and θ＇ should be restrained to promote the nucleation of 19 as possible as to prepare Al-Cu-Mg-Ag alloys with better high-temperature properties.