Ce、La对Mg-Al合金力学性能影响的价电子理论研究

Study on effect of Ce and La for Mg-Al alloy mechanical properties with valence electron theory

基于EET理论,计算了Mg-Al合金中Al2Ce、Al4Ce和Al2La、Al4La的价电子结构,研究了价电子结构与合金第二相强化、高温稳定性及晶粒细化的关系。研究表明,几种第二相的最强键共价电子对数nA值远大于基体α-Mg的nA值,极大的阻碍了位错运动和晶界滑移,提高了合金的强度;第二相的单位体积成键能力FV值也远大于γ-Mg17Al12相的FV值,它们的稳定性更好,有利于改善合金的高温性能;Ce、La提高了液态合金中邻近原子间键合强度,增加了基体的形核率,减缓了晶粒长大速度,进而细化了晶粒,提高合金的力学性能。

The valence electron structures of sencond phase Al2Ce. Al4Ce. Al2La. Al4La are calculated based on the empirical electron theory of solids and molecules（EET）, and the relationship between valence electron structures and the sencond phase strengthen.high temperature stability.grain refinement are studied. The strongest bond nA value of sencond phases are far bigger than substrate α- Mg＇s nA value, which enormously hinder the dislocation movement and grain boundary sliding, enhance the alloy intensity; the total bond - forming ability in unit volumevalue of sencond phases are far bigger than γ - Mg17Al12＇ svalue, which show that their high temperature stability is better and their existence is advantageous to improves the high temperature performance of Mg - Al alloy; Ce.La enhance bonding strength of atoms Neighbored to it in the liquid state alloy, increase the substrate＇ s nucleation rate; slow down the crystal growth speed, then refine the grain size, enhance the alloy mechanics performance.