Change of structure and properties of chemically deposited Ni-P coatings in fusion by continuous CO2 laser

Abstract

1. In treatment of vitrifying coatings of the alloy Ni-12% P, applied to a substrate of steel 45 by continuous laser radiation with power density 60–100 MW/m2, scanning speed of the beam up to 20 mm/sec, and fusion coefficient from 1.0 to 3.3, the effect of renewed amorphization of the layer is not encountered. 2. The microstructure of the fused sections consists of dendrites of solid solution with fcc lattice and a eutectic component whose amount increases with decreasing depth of fusion. 3. The microhardness of the zone of laser alloying (360–450 H) is comparable with the microhardness of the amorphous deposits but much lower than the microhardness of analogous coatings annealed to equilibrium phase composition at 490°C.