Abstract
Deformation induced grain growth in nanostructured materials during thermomechanical processing has been widely reported. However, the governing mechanisms are not well understood. In this study, the microstructural evolution in cryomilled Al-Mg alloy powders (grain size similar to 25 nm) was studied following equal channel angular pressing (ECAP), and hot extrusion, respectively. For ECAP, the nanostructured powder was directly consolidated at 325 not equal to with a back pressure 50 MPa for 4 passes whereas for extrusion, it was annealed for 24 hours at 400 not equal to (grain size similar to 100 nm) and then extruded with a ratio 10:1 (grain size similar to 300 nm). Despite the longer thermal exposure time, the latter sample exhibited a higher yield strength (530 MPa) than the former (470 MPa), indicating the effect of plastic strain on grain growth. The growth process was characterized using TEM and texture measurement. The results showed that grain rotation and coalescence contributed to the observed grain growth.