ABSTRACT
This work aims to analyze the morphological evolution of the commercial A332 aluminum alloy produced via direct casting during the thixoforming process. The characterization of the solid-liquid transition, that is, the working temperatures corresponding to the solid fractions of 77%, 67% and 52% were determined via differential scanning calorimetry (DSC) tests, then the alloy was reheated until the temperature of and maintained for 0 s, 30 s and 90 s treatment times. Through conventional metallography, an increase in the size was observed during the maintenance of the alloy to the semi-solid band for the time of 90 s of treatment being the main mechanism for this change is the phenomenon of ostwald ripening followed by coalescence. It is known that the smallest solid fraction provided higher values of size of primary globules and grains, however, it presented low values of apparent viscosity around 105 Pa.s due to the lower presence of solid phase in the alloy structure and consequently less resistance to flow. This value low apparent viscosity makes the alloy suitable for used as a raw material in thixoforming processes.
Keywords:
Semi-solid material; thixoforming; A332 alloy
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