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半固态材料具有非枝晶固相晶粒均匀分散悬浮于液态基体中的特殊结构。提出了半固态材料中非枝晶组织的形成机制 ,即“晶粒漂移和混和抑制机制”。在电磁搅拌引起的强烈混和对流作用下 ,熔体的动态凝固过程不同于常规铸造时的静态凝固过程。混和对流作用改变了熔体中的传热和传质过程 ,从而决定了凝固组织。晶粒漂移作用极大地增大了非均匀形核率 ,从而细化晶粒 ;混和抑制作用则改变了晶粒生长形态 ,使晶粒在各个方向上可以较为均匀地长大 ,具有规则圆滑的形貌 ,成为非枝晶组织。
Semi-solid materials with non-dendritic solid phase grains uniformly dispersed suspended in the liquid matrix in a special structure. The formation mechanism of non-dendritic structure in semi-solid materials is proposed, that is, the “grain drift and mixing inhibition mechanism”. Under the action of intense mixing convection caused by electromagnetic stirring, the dynamic solidification process of the melt is different from the static solidification process of the conventional casting. Mixed convection changes the heat transfer and mass transfer in the melt, which determines the solidified structure. The grain drift greatly increases the inhomogeneous nucleation rate to refine the grains. The mixing restraint changes the grain growth morphology so that the grains can grow more uniformly in all directions with a regular and smooth Morphology, a non-dendritic organization.