Laser surface alloying of ni film on al-based alloy

Based on SIMS analyses, X-ray diffraction patterns, scanning and transmission electron microscopy observations and chemical analyses at various scales, the mechanisms of LASER surface alloying of Ni coating of Al-based alloy have been investigated. The formation of Al₃Ni primary dendrites in the case of the low thickness of the initial Ni coating is reported and a double dendritic mode is observed in the case of the thicker coating, Al₃Ni₂ followed by Al₃Ni dendrites. A segregation in Si has been observed just below the exposed surface and related to the dendritic solidification mode. The optimized surface treatment parameters have been experimentally determined as a function of the initial thickness of the Ni coating.