氧化铝树枝晶形核机理初探

本文利用快速冷却试样研究了铝脱氧钢液中氧化铝树枝晶的形核机理。通过理论分析认为:氧化铝具有很高的表面能,只能通过非均质过程形核。而硅酸盐夹杂物的表面能只为氧化铝的10~(-8),具备在钢液中均质形核的条件。通过实验研究发现,当钢液加铝脱氧时,溶解铝和硅酸盐夹杂物发生反应,生成部分反应的硅酸盐夹杂物。这些夹杂物具有高铝质的外壳和高硅质的内核,其外壳由于转变应力而开裂。这些裂缝随后则作为基底而形核、生长出氧化铝树枝晶。

A Brief Discussion on Nucleation Process of Alumina Dendrites

The author investigates nucleation mechanism of alumina dendrites in Al deoxidized steel by fast cooling samples. The theoretical analysis indicates that alumina dendrites can only be nucleated by heterogeneous process owing to its highly interfacial energy. The interfacial energy of silicates, however, is only 10-8 times of that of alumina and, thus, the silicates have the precondition of homogenous nucleation in the steel. The investigation has discovered by experiments that when the steel is deoxidized by Al, dissolved aluminium reacts with the silicates inclusions and form partly reacted aluminium silicates which have highly aluminous shells and highly siliceous centres. The shells form cracks due to the transition stress. It is these cracks which function as the substrate to nucleate and grow alumina dendrites.