摘要
Solidification is an important branch of material science.By model calculation and in-situ observation in this work,distinct from traditional solidification of continuous solid growth,the evolution of discrete so-lidification was investigated,and a new principle for discrete solidification is established based on segre-gation evolution in a semi-solid matrix.The solidification evolution of Al-2 wt.%Cu alloy was investigated by model calculation under different initial undercooling and cooling rates,under superimposed multi-scale temperature fluctuations,and under variable temperature fluctuations.The initiation and propa-gation of segregation fluctuations in semi-solid matrix were verified within a traditional dendritic arm.The alternate solid elements evolved from semi-solid matrix act as periodic dams inhibiting serious seg-regation.Based on the new solidification principle,a multi-scale dendritic pattern was reproduced in a two-dimensional calculation.The new solidification principle reveals the essence of multi-scale mi-crostructures as multi-scale segregation patterns and highlights the feasibility of controlling multi-scale microstructures and segregations.
基金
supported by the General Program of the National Natural Science Foundation of China(Grant No.52271041)
the Key Program of the National Natural Science Foundation of China(Grant No.52031013).
