Effects of magnetic field and hot rolling on microstructures and properties of cryoECAPed 1050 aluminum alloy during annealing

The evolution of hardness and microstructures of 1050 aluminum alloy prepared by hot rolling and subsequent equal-channel angular pressing at cryogenic temperature (cryoECAP) after annealing at 150-400 degrees C for 1 h without and with magnetic field of 12 T was investigated. The electron back scattering diffraction pattern (EBSD) and transmission electron microscopy (TEM) were utilized to characterize the grain microstructures and dislocations. It is demonstrated that the hot rolling before cryoECAP produces more equiaxed grains with a smaller average size and a higher fraction of high angle boundaries (HABs) in the subsequent cryoECAPed 1050 aluminum alloy, thus accelerating the recovery and recrystallization of cryoECAPed alloy and produces more homogeneous microstructure during annealing. The magnetic field promotes the recovery and recrystallization and leads to much lower hardness at 150-250 degrees C, while it can suppress the abnormal grain growth and form more homogeneous grain size distributions annealed at 300-400 degrees C.