Deformation of an Al-7Mg alloy with extensive structural micro-segregations during dynamic plastic deformation

The microstructure evolution and deformation behavior of an as-cast Al-7Mg alloy with severe Mg segregation zones distributed on grain boundaries and in interdendrite regions subjected to dynamic plastic deformation (DPD) at both room and liquid nitrogen temperatures have been studied. At low strains, the deformation of the material is found to be mainly through the formation of deformation bands. At high strains, globular ultrafine grains form in the materials due to continuous dynamic recrystallization, which is also the dominant grain refinement mechanism. After deformation to strain of 1.0, the Mg segregation zones are deformed into fine parallel bands distributing along the deformation bands. Moreover, it is revealed that Al8Mg5 particles and the Mg segregation can enhance the formation of deformation bands even in grains with a stable orientation, namely those with one of the {101} planes perpendicular to the compression direction, which can reduce the inhomogeneity of the deformation structure.