Microstructural characterization and mechanical properties of diffusion-brazed AZ91C magnesium alloy to 316L stainless steel

Dissimilar transient liquid phase (TLP) bonding of AZ91C magnesium alloy to 316L stainless steel was carried out using a pure copper filler metal. The bonding process was conducted in two stages where TLP bonding of 316L to Cu interlayer was first performed and then followed by bonding AZ91C to the other side of the copper interlayer. It was indicated that the temperature rise enhanced the inter-diffusion of elements at the AZ91C/Cu interface and encouraged the formation of hard intermetallic Mg2Cu compound. Refinement of Cu grains was observed and attributed to the induced strain from the fixture. This phenomenon assisted the enhancement of mechanical properties of the joints. By increasing the temperature from 495 to 530 degrees C, the shear strength revealed an upsurge of more than 20 %. The presence of Mg2Cu was detected as the main contributor to the increased shear strength and microhardness at elevated temperatures.