摘要
采用合金熔体深过冷与铜模激冷相结合的凝固技术,研究了Fe47Co47Nb2.5Cu2.5B1合金的晶粒细化机制。研究结果表明,合金凝固组织由外层扩大的细晶区和芯部的等轴晶两部分组成。细晶区晶粒细化主要在于铜模激冷提高了该区域熔体的过冷度,导致熔体形核率增大,抑制了晶粒长大,并在大的枝晶应力作用下发生枝晶碎断。合金芯部组织细化则主要是由于细晶区为内部过冷熔体提供了更多形核质点,并且结晶潜热的释放促使枝晶发生熔断。
The grain refinement mechanism of Fe47Co47Nb2.5Cu2.5B1 alloy was investigated by the undercooling combined with copper mould chilling method.The results show that only two parts,i.e.extended outer fine grained region and center equiaxed region,were found in the as-prepared samples.The main origin of the grain refinement in the outer fine grained region of the samples is that the excess undercooling could be brought in the undercooled melts due to the copper mould chilling,so nucleation rate and dendritic stress were enhanced rapidly,which restrain gain growth and result in the break of dendrites.While in the center of the samples,large numbers of substrates to nucleate are produced by the outer fine grained region.And the emission of the latent heat of crystallization makes the dendrites remelt down.
出处
《铸造技术》
CAS
北大核心
2011年第4期453-458,共6页
Foundry Technology
基金
国家自然科学基金项目
50901059
凝固技术国家重点实验室自主研究课题:17-TZ-2007
24-TZ-2009
41-QP-2009
