Deformation mechanism at impact test of Al-11% Si alloy processed by equal-channel angular pressing with rotary die

Al-11%Si (mass fraction) alloy was transformed into a ductile material by equal-channel angular pressing (ECAP) with a rotary die. Two mechanisms at impact test, slip deformation by dislocation motion and grain boundary sliding, were discussed. The ultrafine grains with modified grain boundaries and the high content of fine particles (< 1 μm) were necessary for attaining high absorbed energy. The results contradict the condition of slip deformation by dislocation motion and coincide with that of grain boundary sliding. Many fine zigzag lines like a mosaic were observed on the side surface of the tested specimens. These observed lines may show grain boundaries appeared by the sliding of grains.