Industrial Sintering Response and Microstructural Characterization of Aluminum Powder Metallurgy Alloy Alumix 123

Abstract

In this work, the industrial sintering response of the commercial aluminum powder metallurgy alloy 'Alumix 123' has been examined and the resulting microstructure investigated by optical microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction. Alumix 123 is similar in composition to wrought aluminum alloy 2014 and was revealed to develop a sintered density of 92% of theoretical using standard practices for industrial sintering. Microstructural investigations proved that as a result of industrial sintering, a number of embrittling iron-containing intermetallics are developed in addition to the desirable copper-rich intermetallics. To improve the density of sintered components, procedures were developed for secondary processing by 'sizing' (repressing) in a laboratory setting. The results showed that sizing to the industry standard reduction in height of 5% only closed a portion of open surface porosity and that higher sizing pressures should be used in applications that are sensitive to this microstructural feature.