Modification of casting magnesium alloy AZ31 irradiated by high intensity pulsed ion beams

High intensity pulsed ion beam (C+, H+) irradiation of casting magnesium alloy AZ31 target is carried out with shot times of 1, 5, 10, 20, 30, 50 and 100, respectively. The surface morphologies, phase structure, surface and cross-sectional microhardness ofirradiated samples are characterized. The results show that the shot times of HIPIB irradiation play a great role on the target morphology, subsequent irradiation on the melting crater has previously generated fuzzy or eliminated the trend; melting craters appear again along with increasing the times of irradiation. The surface microhardness increases straightly after the first to 30th irradiation, lying in grain refinement and micro-strain caused by the crystal defects;the 30th to 50th exposure,there is a significant reduction in microhardness,which lies in the evolution of crystal defects, such as dislocation movement leading to the formation of small angle grain boundaries, or even reply recrystallization;the 50th to 100th irradiation slightly reduced the surface hardness, the reason is that radiation's organizational structure and thermodynamic behavior of the surface to reach a steady state. The shock-wave effects the formation of long-hardening.The cross-sectional microhardness away from the surface 30 and 240 m of AZ31,which is 20th irradiation,reach a great value 1.0 GPa and 1.3 GPa,respectively.