【摘要】 用分子动力学理论建立了液态ZA27合金模型,结合计算机编程构造出稀土化合物、α相、α相与液相共存时的原子结构模型,利用递归方法计算了稀土固溶于晶粒内和富集于晶界前沿时的电子结构,以及稀土化合物、α相、液态ZA27合金结构能.由此得出,稀土处于相界区比在晶内更稳定.从而解释了稀土在α相内溶解度很小,结晶时富集于相界前沿液体中,使α晶枝产生熔断、游离、增殖,且稀土化合物可作为α相异质核心细化晶粒的事实,进而从理论上揭示了稀土变质的机理.更多还原

【Abstract】 The liquid ZA27 alloy model was set up by molecular dynamics theory.The atom structure model of the α phase,RE-compound and α phase-liquid interface region in ZA27 alloys were founded by computer programming.Electronic structures of α phase solid dissolved by rare earth elements and that of crystal-liquid growth front enriched by rare earth elements in ZA27 casting alloy were investigated by recursion method.In the same time,the structure energy of RE-compound,α phase and liquid ZA27 alloys were also calculated.The results show that: rare earth elements are more stable in the phase interface region than in α phase,which explains the fact of the solid solubility of rare earth elements in α phase to be very small,and rich in the crystal-liquid growth front.This makes crystal-branch melting and breaking down,dissociating,and propagating;RE-compound can be heterogeneity core of α phase,makeing α phase becoming smaller.All above interprets the modification mechanism of rare earth elements in zinc-aluminum casting alloys from electronic level.更多还原