局部强冷超声介入法半固态制浆机理  

Preparation mechanism of demi-solid dlurry by tegionally dtronger-cooling and mixing by ultrasonic

作　　者：陈国平[1,2] 周天瑞[2] 

机构地区：[1]湖南工业大学机械工程学院,株洲412007 [2]南昌大学机电工程学院,南昌330029

出　　处：《塑性工程学报》2015年第5期135-140,共6页Journal of Plasticity Engineering

基　　金：国家自科基金资助项目(50465003)

摘　　要：提出一种半固态制浆的新方法即局部强冷超声均匀法。以镁合金AZ91D为实验材料,采用正交实验法,结合凝固组织形成非枝晶及细晶组织的机理,研究在间隙式局部强冷和超声介入条件下半固态制浆的效果和相关因素对其的影响,结果表明,在局部强冷及超声介入条件下,熔体中能发生大量非自发形核,并且以球状方式生长;浇注温度为620℃、超声功率为600W时,分别在弱、中和强喷雾条件下,可获得5℃~25℃的过冷度,制备出初生相α晶粒等效圆直径为27μm^48μm、晶粒形状因子约为1.46的半固态浆料。其中中等喷雾条件下,实验结果最优。该方法为解决熔体均匀过冷形核和非枝晶生长提供了一种新的视角。A new semi-solid slurry preparing method,viz.,the technique of stronger-cooling regionally and mixing by ultrasonic,was proposed.Its effects on slurry preparing and relative factors are studied,and its forming mechanism of non-dendrite and fine grain microstructures is analyzed.AZ91 D,as the experiment material,was used to conduct a orthogonal test and a series of additional experiments.The results show that under stronger-cooling regionally and mixing by ultrasonic,the heterogeneous nucleation can occur in quantity in solidifying melt,and the nuclei grow spherically.Under pouring temperature 620℃,ultrasonic power 600 W,and weak/middle/stronger spraying strength in turn,the degree of undercooling of 5℃~25℃can be obtained,and the semi-solid slurry with the equivalent diameter ofα（Mg）primary phase being about 27μm^48μm and the shape factors being about 1.45 can be obtained steadily.The best experimental result can be achieved with middle spraying strength.This method provides a new point of view for solving the problem of the forming of nuclei under uniform undercooling temperature and the nuclei growing spherically.

关 键 词：局部强冷 超声介入 镁合金AZ91D 半固态组织 

分 类 号：TG113.1[金属学及工艺—物理冶金] TB559[金属学及工艺—金属学]