Laser cladding of Ni/Cu/Al functionally graded coating on magnesium substrate

Laser cladding of graded multi-layer Ni/Cu/Al coatings on magnesium substrates was performed with the aim of improving the inherently low corrosion and wear resistance of magnesium. The quality of the coating was found to be good: the interfaces between the different layers are generally free from any major solidification defects such as porosity and cracks. Despite the fact that considerable mixing had occurred in the Al layer, the top Ni layer was free from Al and Mg. The top Ni layer comprises a single solid solution (Ni) phase; its corrosion and wear resistance was found to be excellent. The wear properties of the coating were explained in terms of stacking fault energy and the ratio of hardness to elastic modulus.