摘要
本文立足于经典形核理论和非热形核理论,分析了过冷熔体非平衡凝固中连续形核同位置饱和的竞争.决定过冷熔体形核方式的关键因素是初始熔体的过冷度与异质核心的尺寸.随着净化的进行,熔体过冷度提高,N1,r*以及ΔG*逐渐降低,它们之间的相互竞争使形核方式从位置饱和向连续形核转变,并解释了过冷Ni-Sn与Ni-Si共晶合金中观察到的组织变化.表明低过冷下Ni-Sn合金形核方式为位置饱和;Ni-Si共晶合金中,ΔT<180 K时形核方式为位置饱和,180K以后,形核方式从位置饱和转变为连续形核.
Based on classical nucleation theory and athermal nucleation theory, The competition of nucleation modes i. e. continuous nucleation and site saturation, in non-equilibrium solidification was analyzed. The important factors that determine nucleation modes are the initial melt undercooling and the size of impurity. Undercooling is improved by purification, thus resulting in decrease of N1,r^＊ and △G^＊. The concurring competition causes the change of nucleation mode from site saturation to continuous nucleation. The conclusion was verified by microstructure evolution in undercooled Ni-Sn and Ni-Si eutectic alloys. It is indicated that site saturation is dominant during nucleation process in Ni-Sn eutectic alloy at low undercooling. Additionally, for Ni-Si eutectic alloy the nucleation mode is site saturation while △T〈180 K,it transforms to continuous nucleation while △T〉180 K.
出处
《西安工业大学学报》
CAS
2007年第6期546-550,共5页
Journal of Xi’an Technological University
基金
国家自然科学基金项目(50501020
50395103
50431030)
新世纪优秀人才支持计划(NCET-05-0870)
留学回国人员基金(N6CJ0002)
西北工业大学基础基金
科技创新基金资助
关键词
过冷
非平衡凝固
形核
竞争
undercooling
non-equilibrium
nucleation
competition
