Thixoforming of Otherwise Wrought Aluminium Alloys: Thermodynamic Prediction of Amenable Compositions

Thixoforming-or semi-solid processing- is the shaping of metal components in the semi-solid state. For this to be possible, the alloy must have an appreciable melting range and, before forming, the microstructure must consist of solid metal spheroids in a liquid matrix. Thixoforming is in commercial use but only with the casting alloys A356 and A357. One of the major challenges for thixoforming is to broaden the range of alloys which can be successfully thixoformed and to develop alloys which are specifically designed to be amenable to the process. Here the critical scientific issues for alloy development for thixoforming will be summarized and recent work on the thermodynamic prediction of amenable compositions discussed.