Several profiles with the same extrusion ratio were extruded from three monolithic alloys and five aluminum matrix composites (AMCs) prepared by ingot and powder metallurgy (PM). Specifically, AA6061 and AA6063 were reinforced by 10 and 25 vol.% of Al2O3 and MoSi2 intermetallic particles. To study the wear of the dies, high temperature pin-on-disk tests were performed. The results show that the composite profiles present high surface and dimensional quality and that the die steel wears slightly more against the cast composite. Maximum extrusion pressure (Pmax) depends on profile shape and increases in the following order: bar, T, L and U, and tube. It also increases as volume fraction of reinforcement increases. In general, cast materials are easier to extrude than PM ones, and MoSi2 reinforced AMCs are easier to extrude than Al2O3 ones. AMCs processed by PM have significantly higher hardness than the cast AMC and the monolithic alloys. The PM composites do not need any heat treatment to acquire maximum hardness. By adding reinforcing particles to aluminum, a significant increase in tensile strength and stiffness occur. The high tensile strength and modulus of the present PM composites, without a decrease in specific properties, makes these AMCs interesting for structural applications.

Spanish project TRACE2009_0251 from MICINN, Spain, and EXTRUGASA, Galicia, Spain, are gratefully acknowledged. Thanks are also due to Amalia San Román and Miguel Acedo for their help with the experimental work.

Peer reviewed