Strengthening in deformation-processed Cu-20% Fe composites

Three Cu-20% Fe composites with different iron powder sizes were fabricated using powder metallurgy processes. The strengths of these composites after extensive deformation processing by rod swaging and wire drawing were shown to be anomalously higher than those predicted by rule of mixtures equations. However, the strengths obey a Hall-Petch type relationship with the iron filament spacings. The strengths of the Cu-20% Fe composites after equivalent deformation processing increased with decreasing initial iron powder size. Comparison of a Cu-20% Fe composite with a similar Cu-20% Nb composite showed that Cu-20% Fe was stronger after an identical degree of deformation processing. This increase in strength of a Cu-20% Fe composite over that of a Cu-20% Nb composite correlated with the greater shear modulus of iron compared to niobium using a barrier model for hardening.