铸造锌铝合金稀土变质机理的电子理论研究  

Electronic theoretical study on the modification mechanism of rare earth elements in zinc-aluminum cast alloys

作　　者：刘贵立[1] 李荣德[1] 

机构地区：[1]沈阳工业大学材料科学与工程学院,沈阳110023

出　　处：《物理学报》2003年第9期2264-2267,共4页Acta Physica Sinica

基　　金：教育部高等学校优秀教师资助计划(批准号 :0 0 2 7119)资助的课题~~

摘　　要：根据分子动力学理论建立了液态锌铝合金ZA2 7的模型 ,结合计算机编程构造出了ZA2 7合金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结晶前沿时的电子结构 .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 ,结晶时富集于结晶前沿液体中的事实 ;稀土处于液态和晶态的结构能差相对于铝较大解释了稀土在相界前的富集使α晶枝产生熔断、游离、增殖的观点 .原子间的键级积分计算也表明 ,稀土处于结晶前沿液体中与铝相比不容易结晶到晶体表面 ,起到阻碍晶粒长大 ,细化晶粒的作用 。The atomic structural model of the alpha phase-liquid interface region in ZA27 alloys was set up by combining molecular dynamics theory with computer programming. The electronic structure of alpha phase solid solution with rare earth elements and that of crystal-liquid growth front enriched with rare earth elements in the ZA27 casing alloy were investigated by the recursion method. The calculated results show that rare earth elements are more stable in the phase interface region than in alpha phase. This explains the fact that the solid solubility of rare earth elements in alpha phase is very small,but large in the crystal-liquid growth front. The structural energy difference between the rare earth elements in the crystal-liquid growth front and in the alpha phase is greater than that in Al,which support the view point that rare earth elements enriched in the crystal-liquid growth front can make alpha crystal-branch melt and break down, dissociate, and propagate. Calculations of bond order integrals ( BOIs) also show that rare earth elements in the alpha phase-liquid growth front are not easier than Al to solidify on the surface of alpha phase, so that the growth of alpha grains is blocked, and the alloy is refined, thus illucidating the modification mechanism of rare earth elements from an electronic level for the zinc-aluminum cast alloys.

关 键 词：电子结构 液固相界原子结构模型 稀土变质机理 电子理论 铸造锌铝合金 凝固过程 

分 类 号：TG146.22[一般工业技术—材料科学与工程]