摘要
采用熔盐净化剂与循环过热相结合的方法，对DZ125高温合金晶粒细化机制进行了系统研究。在所获得过冷度范围内（0-180K），发现两次晶粒细化，第一次产生于48～85K，第二次产生于临界过冷度160K之后。枝晶生长理论指出，枝晶重熔大小可以用无量纲过热度来衡量，无量纲过热度随过冷度的增大先增加后减小。理论计算和试验结果表明，小过冷下晶粒细化是由枝晶熟化重熔引起，大过冷下晶粒细化是枝晶破碎再结晶所致。
The grain refinement mechanisms of undercooled DZ125 superalloy melt were systematically investigated by the method of molten salt purification combined with cycled superheating. Within the achieved range of undercooling 0-180 K, there were two processes of grain refinements in the alloy. One took place in the undercooling range of 48-85 K, and the other beyond the critical undercooling 160 K. Based on dendrite growth theory, the tendency of the dendrite remelting can be evaluated with the dimensionless superheating. With the increase of undercooling, the dimensionless superheating increases first and then decreases. Both theoretical calculations and experimental observations indicate that the grain refinement at low undercoolings is caused by the serious dendrite remelting produced by recalescence superheating, and that at high undercoolings by stress originating from the rapid solidification process, which leads to the dendrite disintegration and recrystallization.
出处
《铸造》
CAS
CSCD
北大核心
2009年第7期677-680,共4页
Foundry
关键词
DZ125高温合金
过冷
晶粒细化
再结晶
DZ125 superalloy
undercooling
grain refinement
recrystallization
