Tensile fracture behaviour of Cu- and Ni/Cu-coated Mg alloy (AZ61)

The tensile fracture behaviour of alkaline Cu-, acidic Cu-, and Ni/Cu-coated AZ61 specimens was studied. Experimental results show that the tensile behaviour of an AZ 61 specimen is similar after alkaline Cu electroplating and Ni/Cu electroplating with a Ni thickness of 3 μm. In contrast, the elongation percentage for an AZ61 specimen clearly decreased after acidic Cu-electroplating and Ni/Cu electroplating with a Ni thickness of 15 μm. By observing the fracture surface of coated AZ61 specimens with lower elongation percentages, cracks can be initiated from the Cu deposit into the AZ61 substrate, forming a cracking plateau. However, cracking of the Cu-deposited AZ61 specimen can be hindered by electroplating a Ni deposit. The cracking of uncoated and coated AZ61 specimens during and after a tensile test was discussed.