Experimental investigation of grain boundaries misorientations and nano twinning induced strengthening on addition of silicon carbide in pulse electrodeposited nickel tungsten composite coating

Nanoindentation was performed on silicon carbide (SiC) reinforced pulse electrodeposited nickel-tungsten (Ni-W) composite coating. Addition of 5 vol.% of SiC in Ni-W coating increased the hardness from 10.31±0.65GPa to 14.32±0.63GPa and elastic modulus from 119.74±3.15GPa to 139.26±2.09GPa. Increased hardness and elastic modulus directly translates to the improved strengthening in the coating. An experimental investigation of strengthening mechanism was carried out in Ni-W-5vol.% SiC alloy. Two simultaneous phenomena viz. grain refinement and increased internal strain was observed, which increased the dislocation density from 5.51×1018m−2 to 1.346×1019m−2 on reinforcement of 5vol.% of SiC in Ni-W coating. Increased dislocation density promoted the formation of grain boundary misorientations and nano twinning. Low angle grain boundary, high angle grain boundary and nano twinning were identified using high resolution transmission electron microscope (HR-TEM) image and their role in strengthening mechanism was discussed in details. [Display omitted] •SiC reinforced pulse electrodeposition Ni-W coating was deposited on steel.•Nanoindentation showed the increased mechanical properties on addition of SiC.•Grain refinement and increased internal strain was observed in Ni-W-SiC coating.•Dislocation density increased on reinforcement of SiC in Ni-W coating.•Increased dislocation density triggered grain boundary misorientation and twinning.