Effects of high pressure solidification on dendritic morphology of Al-9.6Mg alloy have been described by Olympus optical microscope. The results demonstrate that while the microstructural dendritic is coarse and broken under normal pressure

dendritic arm keeps completeness in which secondary dendritic arm spacing is decreased and major primary dendritic arm is grown under high pressure. Evolution mechanism of dendritic morphology has been expounded from the viewpoint of effects of high pressure on constitutional undercooling and heat undercooling as well as solute diffusion. High pressure solidification

as an extreme solidification condition

can provide a new approach to change the structural morphology in the alloy.