HOT-WORKING BEHAVIOR OF AL-AL2O3 PARTICULATE-REINFORCED METAL-MATRIX COMPOSITE

The hot deformation behaviour of a particulate reinforced metal matrix composite, manufactured via a casting route and consisting of a 2000 series matrix reinforced with 20 vol.-%Al2O3 particles, was investigat ed over a range of temperatures and strain rates. The behaviour was co mpared with the unreinforced alloy deformed under the same conditions. Both materials exhibited similar hot working behaviour. However under all deformation conditions the composite exhibited flow stresses high er than that of the alloy, but as the deformation temperature increase d and the strain rate decreased, this difference became negligible. Th e activation energy for deformation was determined using constitutive equations. The value determined for the composite was slightly higher than that for the alloy. This suggested that the ceramic particles in the composite force the matrix to undergo additional strain hardening during deformation. Dynamic recovery was the sole restoration process in both materials. No evidence of dynamic recrystallisation was found.