Al-Zn-Cu三元系Al-Zn侧相平衡成分的测定

采用扩散偶电子探针微区分析技术,对Al Zn Cu三元系相图的低Cu区三个固溶体相的相平衡关系及相平衡成分进行了研究·结果发现,在320℃时Cu的加入使得α1/α2,α2/β相平衡时的α1和α2中的Zn含量都降低·在260℃时,添加少量的Cu使得α/β平衡时α中的Zn含量增加·Cu在α1/α2,α2/β和α/β三种相平衡时的分配都不对称,即Cu在后者中的含量远大于前者·这意味着在320℃时Cu的加入使得α1/α1+α2相边界向富Al角趋近;在260℃时Cu的加入使得α/α+β相边界向Zn含量增加的方向偏移·

Determination of Phase Equilibrium Composition on Al-Zn Side of Al-Zn-Cu Ternary System

The phase equilibria and compositions of three solid solutions in the low Cu region of a Al-Zn-Cu ternary system were investigated by means of diffusion couple-EPMA technique. It was found that Zn contents in α1 and α2 both decrease due to Cu additions when α1/α2 and α2/β are both in equilibrium at 320°C; Zn content in α increases with the small amount of Cu when α/β is in equilibrium at 260°C. The distribution ratios of Cu are all unsymmetrical when α1/α2, α2/β and α/β are all in equilibrium, i.e., Cu content in the latter phase is much more than that in the former one. This means that the α1/α1+α2 phase boundary approaches to Al-rich corner due to Cu additions at 320°C, and the α/α+β phase boundary is along the increasing direction of Zn content due to Cu additions at 260°C.