Evaluation of laser cladding of Ti6Al4V-ZrO2-CeO2 composite coating on Ti6Al4V alloy substrate

A titanium metal matrix composite (Ti6Al4V-ZrO2-CeO2) cladding is performed on Ti6Al4V alloy by irradiating a pulsed wave fibre laser source. A varying weight percentage of ceria (CeO2) is added to the composite to study its effect on cladding microstructure, hardness, and wear properties. A detailed microstructure and phase identification study is made using FESEM, XRD, XPS, and EBSD. The presence of CeO2 in the composite refines the microstructure of the clad. It promotes the in-situ formation of ceramic compounds such as Ce1-xO2Zrx, Al2O3, Ti6O, and ZrO2 and restricts acicular α‑titanium growth by favouring equiaxed CeO2 growth. Due to grain refinement and the presence of hard ceramic compounds, the microhardness, COF, fracture toughness, and wear resistance is significantly affected with the variation of CeO2 in the cladding. The lowest coefficient of friction (COF) and highest hardness value of 0.21 and 700HV300 were obtained with samples containing 5 wt% of CeO2. Also, the indicative parameters of wear resistance, such as H/E and H3/E2 computed from the nano-indentation test, are highest in the samples containing 5 wt% of CeO2. The novelty lies in graded grain size and in-situ formed hard and rugged cladding without vertical cracks.