Effects of process variables on the mechanical and physical properties of an Al–Cu–Mg powder metallurgy alloy

The objective of this research was to analyze the effect sizing and heat treatment had on the properties of a 2xxx series aluminum powder metallurgy alloy. Al–2.3Cu–1.5Mg–0.5Sn was used for experimental work. Natural and artificial aging was studied, as well as various sizing pressures and delay times between process steps (ex. sintering and sizing). It was determined that sizing increased tensile yield strength but decreased tensile ductility and fatigue resistance. Yield strength increased as much as 32% when sized at 400 MPa, whereas ductility and fatigue strength were reduced by up to 51% and 31%, respectively. Delay time between sintering and sizing (T2 samples) did not appear to significantly impact mechanical properties. Through differential scanning calorimetry it was determined that sizing impacted the precipitation of S-type precipitates. It was inferred that there was a preferential tendency for S1-type precipitates to form in sized samples, suppressing full aging to S2-type.