Dynamical coarsening processes of microstructures in non-dendritic AlSi_7Mg alloy remelted in semi-solid state

摘要

The microstructural variation in the non-dendritic AlSi_7Mg samples remelted in the semi-solid state has been investigated. It is proposed that the primary α-Al phases are mainly coarsened by connecting the secondary arms or fine primary α-Al phases together at the stage of a small quantity of liquid and slowly coarsened through diffusion at the stage of a great quantity of liquid. The dynamical coarsening equation controlled by diffusion is in good agreement with the equation of d~3 -- d_o~3 = kt and the effect of the starting microstructures on the coarsening of primary α-Al phases is gradual- ly decreased when the soaking time is long enough.