Deformation behavior of semi-solid Zn–Al alloy filler metal during compression

We investigated the compression of a semi-solid Zn–Al alloy disc as it is often used as a filler metal to braze aluminum alloys and their composites. Three different size discs were used with height-to-diameter ratios (h/d) of 0.6, 0.3 and 0.1. Stress–strain curves were obtained during disc compressions. The maximum stress obtained during the compressions increased with a decrease in disc size (h/d). Configuration changes of the solid grains in the semi-solid Zn–Al alloy discs were examined during the compressions. There exist a hard deformation area with slight changes in grain shape and a severe deformation area with significant changes in grain shape on the contact surface of the discs. And with a decrease in disc size (h/d) the severe deformation area enlarged and the hard deformation area dwindled from the edge towards the center during the compression. Interactions of the semi-solid Zn–Al alloy disc with the compressing block on the contact surface during a compression was qualitatively analyzed on the basis of the solid grains’ action in the different deformation areas. For the smaller disc (h/d) the contact surface interaction showed an intense compression in the center and a combination of shearing and compression over the remainder of the surface during the compression. This was beneficial to the disruption of the oxide film on the contact surface for the semi-solid brazing of SiCp/Al composites when the disc was used as a filler metal.