Dilution effect on the formation of amorphous phase in the laser cladded Ni–Fe–B–Si–Nb coatings after laser remelting process

► We deposited Ni–Fe-based amorphous composite coating using HPDL processing. ► High laser power resulted in high dilution ratio of the coating. ► Low dilution ratio resulted in high amorphous content in the coating. ► Microhardness of 1200HV0.5 was obtained due to formation of amorphous phase. Ni–Fe–B–Si–Nb coatings have been deposited on mild steel substrates using high power diode laser cladding. Scanning laser beam at high speeds was followed to remelt the surface of the coatings. Different laser cladding powers in the range of 700–1000W were used to obtain various dilution ratios in the coating. The dilution effect on the chemical characterization, phase composition and microstructure is analyzed by energy dispersive spectroscopy, X-ray diffraction and scanning-electron microscopy. The microhardness distribution of the coatings after laser processing is also measured. The results reveal that Ni-based amorphous composite coatings have successfully been fabricated on mild steel substrate at low dilution ratio when the cladding power was 700W, 800W and 900W. While at high laser power of 1000W, no amorphous phase was found. The coatings with low dilution ratio exhibit the highest microhardness of 1200HV0.5 due to their largest volume fraction of amorphous phase.