摘要
采用熔融玻璃净化与循环过热相结合的方法研究Cu～20%Pb亚偏晶合金的凝固组织,用BCT-LKT枝晶生长模型对深过冷凝固过程的热力学参数进行了计算,分析了过冷Cu-20%Pb亚偏晶合金的凝固机制.结果表明,在低过冷度下,Cu-20%Pb亚偏晶合金凝固组织由粗大的Cu枝晶和Pb相组成.随着过冷度的增大,Cu枝晶和Pb相细化,Pb相分布均匀.但在不同的过冷度范围,凝固组织细化机制不同.过冷度小于200K时,快速凝固阶段结晶潜热集中释放造成的温度回升引起枝晶大量重熔是枝晶细化的主要因素;过冷度大于200K时,枝晶高速生长导致枝晶各部位的不均匀收缩及枝晶骨架间液相的高速流动会使枝晶受力产生碎断,枝晶重熔和枝晶碎断共同作用使得枝晶发生细化.
The solidification structure of the Cu-20%Pb hypomonotectic alloy was studied by combining the melting glass purification and the cyclic superheating, the thermomechanical parameters in the process of the undercooled solidification were calculated by using the BCT-LKT dendritic growth model, and the solidification mechanism of the alloy was analyzed. The undercooled solidification structure of the alloy consists of the coarse α（Cu） dendrites and Pb phases distributed between or in the dendrites. As the undercooling increases, the dendrites and Pb phases are refined and their distributions uniformed. But the refinement mechanisms are different under different undercoolings. When the undercooling is below 200 K, the latent heat released during rapid solidification will rise the temperature, therefore, more dendrites are melted and refined. When the undercooling is above 200 K, the rapid growth of the dendrites leads to both the uneven contraction of the dendrites and torrent flow of the interdendritic melt, both dendrites remelting and fragmentation make the dendrites refined.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第11期1138-1144,共7页
Acta Metallurgica Sinica
基金
陕西省教育厅专项科研计划项目03JK132
陕西省自然科学研究计划项目2003E111资助~~
关键词
Cu-20%Pb
亚偏晶合金
深过冷
枝晶重熔
枝晶碎断
Cu-20%Pb, hypomonotectic alloy, deeply undercooling, dendrite remelting, dendrite fragmentation
