摘要
异质形核是形核发生的主要形式.经典形核理论对基底界面作了理想化平面假设,然而实际异质形核体系中理想平直的固体界面是不存在的,这导致了异质形核描述与实际情况的偏差.考察了固相晶胚在非平整界面上的异质形核过程,基于Wenzel润湿模型,分析了非理想界面的粗糙度因子对固相晶胚形核功的影响规律.结果表明:当基底与晶核之间的本征润湿角小于90°时,基底界面越粗糙越有利于形核;本征润湿角大于90°时,基底界面越粗糙越不利于形核.同时,游离晶胚在基底上润湿是球冠晶胚形成的重要途径,粗糙界面润湿过程中界面自由能的变化会对形核产生重要影响.
Heterogeneous nucleation plays an important part in the solidification process.In order to describe the effects of the substrate surface on the heterogeneous nucleation,an idealized planar interface between the nucleus and the substrate is assumed in the consideration of the classical nucleation theory,but this may lead to the deviation of the experimental results from the theoretical predictions,since there is no idealized planar surface on any actual substrate.The heterogeneous nucleation procedure of solid phase on rough substrate surface is investigated,and the effect of the roughness factor of the substrate on nucleation energy is analyzed based on the Wenzel wetting model.The results show that when the intrinsic contact angle between the substrate and the nucleus in the base phase is less than 90°,higher roughness of the substrate surface makes it easier to induce heterogeneous nucleation;when intrinsic contact angle is greater than 90°,higher roughness would restrict the nucleation on the substrate surface.Meanwhile,attaching and wetting drift embryos on the substrate play an important part in the formation of effective nucleus on the substrate,while the change of interfacial free energy in the wetting process of the embryos on the rough substrate surface has an important effect on heterogeneous nucleation behaviors.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2011年第6期530-535,共6页
Acta Physica Sinica
基金
国家自然科学基金(批准号:50901061
50771083)
凝固技术国家重点实验室基金(批准号:02-TZ-2008
36-TP-2009)资助的课题~~
