Effect of Prior Rolling on Microstructures and Property of Diffusion-Bonded Mg/Al Alloy

In this study, magnesium alloy AZ91, which was cast by double roll casting system, was rolled by a rolling mill. Then, rolled magnesium alloy and magnesium alloy without being rolled were, respectively, welded with aluminum alloy 6061 by diffusion bonding method. Furthermore, annealing process was applied to refine the microstructure and improve mechanical property. The microstructure and elemental distribution of diffusion zone were investigated with a scanning electron microscope (SEM), an electron probe micro analyzer (EPMA), and a transmission electron microscope (TEM). In addition, hardness and tensile strength were measured. When cast magnesium alloy was used, the width of diffusion layers was wider than that with rolled magnesium alloy. And the width increased with the increasing annealing temperatures. Element distribution of specimens with annealing was more uniform than that did not undergo annealing process. Furthermore, tensile strength turns to be strongest after annealing at 250 degrees C. And the strength of the specimens with rolled magnesium alloy was stronger than that with cast magnesium alloy which was not rolled.