The primary a phase underwent a series of change from plane front, cystiform, cystiform & dendrite, thick dendrite to thin dendrite after rate is steady, with the increase of solidification rates and the interface morphology evolution. 随着凝固速率的提高,凝固界面形态的演化,在速率保持稳定后会出现平面晶组织胞晶组织胞/枝状晶粗树枝晶组织细树枝品组织等一系列的形貌变化。