采用多相场法研究三维层片共晶生长的厚度效应

Investigation on the effect of lamellar thickness on three-dimensional lamellar eutectic growth by multi-phase field model

采用Kim,Kim,Suzuki和Ode提出的KKSO多相场模型,研究了固定层片间距不同层片厚度条件下三维过共晶层片生长形态的演化行为.研究表明,层片厚度对层片生长过程有较大影响.当层片厚度较小时,厚度效应较弱,类似于二维生长.随着层片厚度的增加,厚度效应逐渐增强并开始产生厚度方向的振荡失稳,造成层片取向的偏转.层片厚度的进一步增加,使层片宽度方向和层片厚度方向的振荡交替出现.当层片厚度大于层片宽度时,厚度效应逐渐强于宽度效应,最终宽度方向的振荡被抑制,仅在厚度方向形成类似于二维的1λ振荡.模拟结果还表明,不同层片厚度下液/固界面前沿平均过冷度变化与形态变化的趋势相符.

Using the multi-phase field model proposed by Kim,Kim,Suzuki and Ode（KKSO）,numerical studies have been carried out to investigate the effect of lamellar thickness on the lamellar eutectic growth in three dimensions.Simulation results showed that the lamellar thickness has significant effects on the eutectic morphology evolution with a given lamellar spacing.When the lamellar thickness is comparatively small,the eutectic lamellar growth is similarly to the two-dimensional case.Increasing the lamellar thickness,the effect of lamellar thickness becomes stronger,as a result,the lamellar structure distorts vertically,and oscillations on both the direction of the width and the direction of the thickness occur alternatively after a further increase of the lamellar thickness.When the lamellar thickness is bigger than the lamellar width,a stronger oscillation in the thickness direction than that in the width direction occurs,and eventually the oscillation in the width direction is suppressed but only an approximate 1λ oscillation in the thickness direction can be found.Moreover,simulation results also showed that the change of undercooling is consistent with the morphology transition.