合金化对非晶形成能力影响的电子理论计算

Electronic theory calculations of alloying effect to amorphous alloy forming ability

根据分子动力学理论建立了非晶Ni64Pd16Al2 0 的结构模型 ,利用Recursion方法计算了Ni64X16Al2 0 系非晶及相应晶态的电子结构。结果表明 ,Ni64X16Al2 0 合金的非晶形成能力与过渡元素局域电子态密度的双峰位置、电子得失形成的离子键及非晶与晶态合金的总结构能差有关。局域电子态密度的结果表明 ,Al与过渡元素间存在电子耦合—共价相互作用 ,合金元素使Ni64X16Al2 合金非晶形成能力从强到弱的顺序是 :Ir,Pt,Rh ,Pd ,Au ,Ag ,Cu ;Ni64X16Al2 0 合金中离子键的存在使其非晶形成能力增强。非晶与晶态合金的总结构能差越小的过渡元素使其形成非晶的驱动力越强 ,对非晶形成越有利 ,由此得出的规律与上述共价键的作用规律一致。

The atom structure model of Ni 64 P d 16 Al 20 amorphous alloy was set up by using molecular dynami cs theory . The electronic structure calculations of crystal and amorp hous alloy Ni 64 X 16 Al 20 by Recursion meth od reveal that the amorphous alloy forming ability is related to the location of the double-peak (or tri-peak) of local density of states (LDOS) in low energy region, electrovalent bond formed by gaining or losing electrons and the total structure energy difference of amorphous alloy Ni 64 X 16 Al 20 to crystal alloy. The common conclusion drawn from LDOS and the t otal structure energy difference of amorphous alloy Ni 64 X 16 Al 20 to crystal alloy is: when transition element Ir, Pt, Rh, Pd, Au, Ag, Cu is added into NiAl alloy, the amorphous alloy forming ability we akens in the same order. The electrovalent bond existing in Ni 64 X 16 A l 20 alloy enhances the amorphous alloy forming ability too.