Microstructure and properties of some extruded copper–phosphorus alloys

Abstract

Five Cu-P alloys have been produced by extruding cast and heat treated billets. This paper reports the effects of the extrusion variables on the resultant structure and properties. It is shown that the recrystallized structure observed in the α phase is produced by dynamic recrystallization occurring during the deformation process. The α grain size is determined by the processing parameters, but considerably modified in the two phase alloys by the Cu₃P phase such that it may be quantified only by expressing it as a function of both extrusion ratio and temperature compensated strain rate. The deformation process is considerably affected by the large volume of second phase: the Cu₃P being either broken or elongated during the extrusion process. The mechanical properties are influenced by the extrusion conditions and may be further modified by an annealing process which causes precipitation in the α phase and coalescence of the Cu₃P phase. The mechanism of fracture during tensile testing is also reported.