Optimization　of　process　variables　for　laser　cladding　of　Ni-based　alloys　was　performed　using　the　pre-placed　powder　method.　The　microstructure　of　laser　clad,　under　optimal　processing　conditions,　and　furnace　melted,　under　near　equilibrium　conditions,　Ni-based　alloys　has　been　comparatively　investigated　by　X-ray　diffraction　(XRD),　scanning　electron　microscopy　(SEM)　and　transmission　electron　microscopy　(TEM)　techniques.　Comparison　of　the　microstructures　of　the　laser-clad　and　furnace-melted　alloys　revealed　a　remarkable　difference.　The　microstructure　of　the　laser　cladding　is　complex,　composed　of　blocky　CrB　type　chromium　carbon　borides:　orthorhombic　structured　Cr7C3　type　dendritic　carbides,　cellular-dendritic　gamma　-Ni　solid　solution,　different　interdendritic　eutectics　and　amorphous　phases　along　grain　boundaries.　The　interdendritic　eutectics,　either　gamma　-Ni　+　M23C6　or　gamma　-Ni　+　Ni3B　(Ni2B)　can　form　depending　on　the　local　composition,　gamma　-Ni　+　Ni3B　stable　solidification　and　gamma　-Ni　+　Ni2B　metastable　solidification　exist　simultaneously　because　of　the　non-equilibrium　rapid　solidification　involved　during　the　laser　cladding.　In　contrast,　the　microstructure　of　furnace-melted　Ni-based　alloy　under　near　equilibrium　solidification　is　composed　of　hexagonal　structured　Cr7C3　type　carbides　with　hexagonal　prism　morphologies,　near-equiaxed　gamma　-Ni　solid　solution　dispersed　with　fine　Ni3Si　precipitates,　gamma　-Ni　+　Ni3B　near　lamellar　eutectic　and　near-spherical　Ni3B　compound.　gamma　-Ni　is　the　main　microstructural　constituent　in　both　the　laser　clad　and　furnace　melted　alloys.　From　the　grain　size,　it　was　evident　that　the　former　is　one　to　two　orders　finer　than　the　latter.　(C)　2001　Elsevier　Science　B.V.　All　rights　reserved.