The effect of extrusion temperature on the development of deformation microstructures in 5052 aluminium alloy processed by equal channel angular extrusion

Commercial 5052 aluminium alloy was used to study the effect of extrusion temperature on the development of deformation microstructures processed by equal channel angular extrusion (ECAE). The extrusion temperatures used were between 50 and 300 °C, and the cumulative equivalent strain was 5.6. Transmission electron microscopy was adopted to characterize quantitatively the metallographical parameters, namely grain size, grain aspect ratio, and boundary disorientation. Raising extrusion temperature causes grain size to increase, grain shape to become more equiaxed-like, and a dramatic increase of low angle boundaries. Both grain and subgrain boundaries with low disorientations are formed at elevated temperatures. Comments on disorientation measuring techniques in transmission electron microscope are also given.