Pulse electrodeposition of nano-crystalline Ni-W alloy and the influence of tungsten composition on structure, microhardness and corrosion properties

•The influence of pulse parameters on composition, micro-hardness, crystal structures and corrosion resistance of Ni-W alloys were studied.•The alloy obtained from lower frequency (10 Hz) shows higher micro-hardness for all the duty cycles and the maximum value obtained is 846 HV.•The lower W composition shows pure cubic crystal structure and higher W composition shows the cubic and tetragonal mixed crystal phase.•The alloy deposited at 80 % duty cycle and 10 Hz frequency gives the best corrosion protection and the corrosion rate is 2.8 mpy. In this work, nano-crystalline Ni-W alloy films with various tungsten compositions were deposited on mild steel substrate using pulse electrodeposition method. The influence of pulse parameters on composition, crystal structure, microhardness and corrosion properties were studied. The tungsten composition in Ni-W alloy deposits were influenced by pulse deposition parameters and it is varied from 9.51 at% (lower) to 27.7 at% (higher). The influence of tungsten composition on crystal structure, crystallite size, microhardness and corrosion properties were studied. The lower tungsten composition in Ni-W alloy deposit gives pure cubic crystal structure and the higher tungsten composition gives mixture of cubic and tetragonal crystal structure. The alloy deposited using higher pulse duty cycle and lower pulse frequency gives higher microhardness properties and corrosion resistance behaviors. The smallest crystallite sizes and 16–18 at% of tungsten composition in Ni-W alloys favor better microhardness and corrosion resistance properties.