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.
The liquid ZA27 alloy model was set up by molecular dynamics theory. The atom structure model of the a phase, RE-eompound and a phase-liquid interface region irt ZA27 alloys were founded by computer programming. Electronic structures of a phase solid dissolved by rare earth dements 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 REeompound, a phase and liquid ZA27 alloys were also calc^ated. The results show that： rare earth elements are more stable in the phase interface region than in a phase, which explains the fact of the solid solubility of rare earth dements in a phase to be very small, and rich in the crystal-liquid growth front. This makes crystal-branch melting and breaking down, dissociating, and propagating; REcompound 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.
出处
《沈阳师范大学学报（自然科学版）》
CAS
2006年第3期283-285,共3页
Journal of Shenyang Normal University:Natural Science Edition
基金
国家自然科学基金资助项目(50571071)
辽宁省教育厅高等学校科学研究计划项目(05L297
2004C008)
关键词
液固相界原子结构模型
连分数方法
电子结构
稀土变质机理
atomic structure model of a phase-liquid interface
method of recursion
electronic structure
modificationmechanism of rare earth
