Reproducibility of Cell Structure and Mechanical Properties of Al-Si-Mg/SiCP Composite Foams in Relation to the Foaming Temperature

A359 aluminum alloy composite containing 20 vol. % silicon carbide particles was remelted, and 100-mm diameter foam ingots were prepared using 0.75 wt. % of titanium hydride (TiH2). Three identical experiments each were carried out at two foaming temperatures (640 and 660 °C) to check the reproducibility of the cell structure and foam properties. Foams made at 640 °C were reproducible in terms of foam expansion, cell size and cell size variation along the ingot height. The property scatter, evaluated in terms of relative standard deviation, is similar for density and modulus of the foam. For compressive plastic strength, the scatter is double than for density. The density and mechanical properties are reproducible within these scatters. Foams prepared at 660 °C, on the other hand, suffered from liquid foam collapse during solidification and hence couldn’t be qualified for detailed study of reproducibility. The collapse resulted in distortion of the foam ingot and elongated cell structures in other parts. However, the cell size and mechanical properties in the un-distorted region are comparable with those foamed at 640 °C. Overall, good quality cell structure and consistent mechanical properties could be obtained in foams processed at 640 °C.