Microstructural Study of Primary Solid Particles in High Density Semi-Solid Al-Zn-Mg Alloy during Stirring
The formation and character of grain boundaries in the primary solid particles observed in the metal slurries of stircast Al-4wt%Zn-1wt%Mg alloy were studied. In the semi-solid state of the solid fraction (fs) of more than 0.5, fracturing of solid particles appears to be dominated by shear force at high temperature, whilst in fs < 0.4 dendritic fragmentations are expected to occur by grain boundary melting. In case of shear rupture at fs > 0.5 coarsening of spherical solid particles takes place by Gibbs-Thompson effect of small particles remelting leading to solute redistribution.
C.G. Kang, S.K. Kim and S.Y. Lee
J. H. Lee et al., "Microstructural Study of Primary Solid Particles in High Density Semi-Solid Al-Zn-Mg Alloy during Stirring", Solid State Phenomena, Vols. 116-117, pp. 308-311, 2006