摘要
Ni－50％Cu合金随过冷度的增加发生两次明显的晶粒细化过程，第一次产生于50—100K的过冷度范围内，第二次发生于临界过冷度220K之后实验首次发现高过冷度下细化合金的晶粒内含有枝晶亚结构理论分析指出，枝晶重熔倾向的大小可用枝晶主干中最先析出的固相在再辉过程中的无量纲过热度来衡量，该无量纲过热度随原始过冷度的增加先增后减，其最大值对应于第一次细化发生的过冷度区间热力学计算和组织分析表明，小过冷下的晶粒细化是由枝晶重熔引起的，而高过冷下的细小晶粒是应力作用下枝晶破碎及再结晶后的产物。
With undercooling increasing, the undercooled Ni-50%Cu alloy underwent two grain refinement processes. One occurred in the undercooling range of 50 -100 K and the other one at the undercoolings higher than the critical value 220K where the refined crystal possesses the dendritic substructures. It is suggested that the tendency to remelting of the primarily formed dendrite can be evaluated with the dimensionless superheating of the earliest frozen part in the dendrite stems during recalescence. The dimensionless superheating increases first and then decreases with increasing undercooling, and its highest value corresponds to the undercooling range in which the first grain refinement takes place. Both the thermodynamic analysis and the crystal cotheuration indicate that the grain refinement at low undercoolings is caused by the remelting of solid and that at higher undercoolings by stress which leads to the disintegration and recrystallization of the primary dendrite.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
1998年第2期113-118,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金!59431011
关键词
过冷
晶粒细化
热力学
镍铜合金
过冷度
undercooling
Ni-Cu alloy
grain relinement
thermodynamic analysis
