Dislocation hardening coupling between hard matrix and soft zones in a dual-phase heterostructured material

Abstract Strain hardening coupling between hard and soft zones is still not well understood in heterostructured materials. Here we report the coupling of dislocation hardening between hard iron matrix and soft copper zones in heterostructured Fe-40Cu dual-phase materials. Dislocation hardening is the predominant hardening mechanism in the Fe-40Cu materials, as dislocations dominate plastic deformation in both iron and copper. Low-temperature annealing kept highly deformed iron matrix strong and inductile but softened copper zones by promoting recrystallization in them. This raised plastic incompatibility and strain partitioning between iron matrix and copper zones during deformation. As a result, dislocations accumulated dramatically in copper zones but barely in the iron matrix. Copper zones produced high dislocation hardening to compensate for the low one of the iron matrix, raising the total strain hardening of the heterostructured Fe-40Cu materials. Lowering the plastic incompatibility between the iron matrix and copper zones weakened the strain partitioning between them and consequently depressed the dislocation hardening of copper zones. The role that copper zones played turned from producing high dislocation hardening to stabilizing the plastic deformation of heterostructured Fe-40Cu materials at the high strain level.