CAJ | 학술논문

液相分解是一些合金在快速凝固时产生的特殊相变行为.研究了不同冷却速度下Cu-30%Fe合金的凝固过程.Cu-30%Fe二元合金铸锭的微观组织是由铜基体和铁枝晶所组成.当过冷度较大时,位于样品自由表面区域比接近冷却铜板区域的冷却速度小,铁枝晶的存在是该区域微观组织的最大特征,它反映了该区域的凝固方式为正常的凝固方式.样品中心层微观组织的最大特征是存在着尺寸较大的铁球形粒子,它反映了在该区域Cu-30%Fe熔体的凝固过程中过冷液相经历了液相分解过程.数量众多的直径约为几微米的铁粒子和铜基体组成了冷却表面的微观组织.这些铁粒子是被细化了的液相分解铁粒子.液相分解会使合金微观组织产生一定程度的粗化,但提高凝固过程的冷却速度可以显著细化液相分解组织.
액상분해시일사합금재쾌속응고시산생적특수상변행위.연구료불동냉각속도하Cu-30%Fe합금적응고과정.Cu-30%Fe이원합금주정적미관조직시유동기체화철지정소조성.당과랭도교대시,위우양품자유표면구역비접근냉각동판구역적냉각속도소,철지정적존재시해구역미관조직적최대특정,타반영료해구역적응고방식위정상적응고방식.양품중심층미관조직적최대특정시존재착척촌교대적철구형입자,타반영료재해구역Cu-30%Fe용체적응고과정중과랭액상경력료액상분해과정.수량음다적직경약위궤미미적철입자화동기체조성료냉각표면적미관조직.저사철입자시피세화료적액상분해철입자.액상분해회사합금미관조직산생일정정도적조화,단제고응고과정적냉각속도가이현저세화액상분해조직.
Liquid phase separation is a special phase transformation for some alloys in rapid solidification process.The solidification processes of Cu-30%Fe alloys were studied under different cooling rate.The microstructure of Cu-30%Fe binary alloy ingot was made up of copper base and iron dendrite.For a larger supercooling,the cooling rate of free surface zone was smaller than that of the zone near the cooling copper plate,iron dendrite was the feature of the microstructure in free surface zone,which meant that the selidification process in the zone was a normal solidification process.The larger spherical iron particles were the feature of the microstructure in the center layer,which meant that the liquid phase separation happened in the solidification process of Cu-30%Fe melt.The microstructure of cooling surface was made up of large uumbers of iron particles with several micron diameter and copper base.These iron particles were the refined iron particles from liquid phase separation.Liquid phase separation could make the microstructure become coarse.but the microstructure from liquid phase separation could been observably refined by increasing the cooling rate of solidification process.