The solidification of squeeze cast AlCu4Ti alloy

The results of examining the solidification process of the squeeze cast AlCu4Ti alloy have been presented. A simulation of the alloy solidification has been described for both the equilibrium conditions taking into account squeeze pressure and the non-equilibrium conditions under the assumption of the lack of diffusion in the solid state (Scheil model). Experiments have been held for plate castings squeezed under the pressure ranging from the atmospheric one to the value of 90 MPa. The derivative differential thermal analysis (DDTA) method has been used for determining the phase transition point, solidification rate and the degree of alloy supercooling dependent on the squeeze pressure. It has been found that the solidification rate is increased by almost seven times for squeeze castings as compared with the gravity castings. Squeezing causes also a significant refinement of the alloy dendritic structure and removes gas and shrinkage porosity, characteristic for die castings. The high quality AlCu4Ti-alloy castings can be obtained already at the 30 MPa pressure.