Mechanical Properties of Al–30Si–5Fe Alloy Using Combination of Rapid Solidification and Thixoforming Processes

Abstract

In this study, a combination of rapid solidification (melt-spinning) and semisolid forming (thixoforming) processes was used to refine the coarse microstructure of “as-cast” Al–30Si–5Fe alloy and improve its mechanical properties. Al–30Si–5Fe ribbons produced by the melt-spinning process were pulverized and subsequently consolidated at 300 °C in an argon atmosphere. Prepared specimens were thixoformed at temperatures ranging from 580 to 700 °C for various holding times. Some cast samples were also directly thixoformed as reference. In all thixoformed samples, microstructures were modified and needle-like intermetallic compounds as well as silicon particles in the as-cast part were changed into rounded corners or polygonal shapes with uniform distribution. Macro-hardness of up to 165 HV10 (which is almost twice as much as-cast sample) was obtained from a meltspun sample held for 5 min at 700 °C and then thixoformed. Compression strength and malleability increased 31 and 57%, respectively, and a 33% reduction in wear coefficient was obtained in this sample compared to the as-cast alloy.