Hot tearing phenomena in Al-Cu alloys : grain refinement effect

In order to estimate the influence of the mushy zone rheology on hot tearing phenomena, mechanical experiments are conducted on solidifying Al-8wt % Cu alloys, refined and unrefined. Shear loading tests in a Couette rheometer are used to propose a rheological model including the influence of the solid phase morphology and volume fraction. Tensile loading experiments point out that mechanisms of cavitation in continuous liquid films lead to hot cracking. Finally, a hot tearing model is developed by considering nucleation and growth of cavities in a continuous liquid film surrounded by a mushy zone with a dendritic or an equiaxed structure.