Effects of Casting Temperature and Iron Content on the Microstructure of Hypoeutectic A380 Aluminium Alloy

Abstract

Casting temperature and iron content are among the most important factors in obtaining superior mechanical properties in hypoeutectic Al–Si alloys. An A380 aluminium alloy that is one of the most widespread alloys used in high-pressure diecasting was selected for examining different iron contents and casting temperatures. The alloy with contents of about 0.7 and 1.2 wt% Fe was cast at different temperatures in the range between 680 and 960 °C with 70 °C interval from each other. The outcome indicates that dendrite arm spacing does not change significantly at different cast temperatures or iron contents. From 820 °C in low-Fe containing alloy and from 890 °C in high-Fe containing alloy, the precipitation of harmful β-phase is suppressed. Moreover, blocky or Chinese script α-Fe compounds become the dominant phase throughout the microstructure. The results suggest A380 with lower Fe content at casting superheat of 100 °C would result in uniform microstructure and removal of detrimental β-phase.KeywordsAl–Si–FeIntermetallicSuperheat temperatureFe content