摘要
选用透明合金NH4Cl-70%wtH2O溶液,考察了振动条件下2种不同粗糙度等级的激冷表面晶体形核特性。发现通常情况下表面粗糙程度对表面形核没有显著影响;表面形核具有明显的局域性,易于形核的位置具有良好的重复性。采用原子力显微镜观察了表面微观形貌,结果发现形核点区域与不形核点区域之间微观形貌存在明显差异,形核点微区均存在大小约为50～100 nm的凹坑,其尺度与临界形核半径相近。
Abstract.The characteristics of crystal nucleation on a chilling solid surface with two different roughnesses under vibration were investigated using a transparent NH4CI-70% wtH20 alloy. The results indicate that the average surface roughness has not affected the nucleation significantly~ surface nucleation on the chilling solid surface has a distinctively localized behavior, and the sites which are easy to nucleate have good repeatability. The geometric micro-pattern of the chilling solid surface is examined with an atomic force microscope, It was found that there is an obvious difference in the areas with and without active nucleation sites. Some notches and pits with the size of 50～100 nm in the magnitude of the critical nucleation radius may serve as active nucleation sites while those small convex apices never act as active nucleation sites.
出处
《铸造技术》
CAS
北大核心
2007年第8期1036-1038,共3页
Foundry Technology
基金
(国家973专题(2004CB619107)
自然科学基金(50571029)
博士后科学基金(20060391012)资助
关键词
晶体形核
表面粗糙度
临界形核半径
振动
Crystal nucleation
Surface roughness
Critical nucleation radius
Vibration
