Laser alloying of aluminium with electrodeposited nickel: optimisation of plating thickness and processing parameters

Commercial-purity aluminium (CP-Al) was laser alloyed with electrodeposited nickel using a high-power CW CO2 laser. For process optimisation, nickel was electroplated at 12, 24 and 35 μm thickness, and different laser processing conditions were used. The nickel-alloyed aluminium attained a Vickers hardness of 300–950 HV, which is considerably higher than the base aluminium hardness of 35 HV. The laser-alloyed coating (LAC) contains intermetallic nickel–aluminide phases and a dendrite microstructure. The 35 μm thick nickel layer is efficient in laser alloying CP-Al for producing a homogenous coating layer (at a laser energy density of 4.1 kJ) with a high hardness of 600–950 HV and a large case depth (650 μm).