Microstructural evolution of Al-Cu alloy in semi-continuous casting was simulated by means of a multi-scale calculation method. A new method for semi-solid alloy design was proposed on the basis of microstructural simulation. Temperature field and phase transformation models were established to simutate continuous casting

in which solid fraction was used to couple the calculation of macro-scale and mesoscale. Non-physical boundary for outlet side of mold in continuous casting was established based on an extrapolation method

which exhibits high efficient accuracy for steady temperature field. Effects of chemical composition

pouring temperature and pouring velocity on microstructure and constituent distribution of Al-Cu alloy were simulated by the multi-scale model. The results reveal that grain is grown dendritically and form grain boundary with high alloy concentration due to the merging of adjacent grain with different orientations. The desirable semi-solid microstructure in the Al-Cu alloy can be observed with 8.0% Cu content

where microstructure of the alloy is slightly related to casting velocity and pouring temperature. The simulated results are well in agreement with experimental ones in ZL201 alloy

which shows that the multi-scale simulation is an effective method to simulate design of semi-solid alloy and to predict processing parameters.