The microstructures of three electroless Ni-Mo-P alloy deposits at various heat treatment temperatures were studied by transmission electron microscope (TEM). Heating these deposits from 200 to 800-degrees-C produces structural changes. Hardness of these deposits increased when heat treatment temperature was 400-degrees-C or below, and is shown to be related to the precipitation of Ni3P phase within the Ni and/or Ni-Mo solid solution matrix. When heat treatment temperature was 500-degrees-C or above, Ni3P particles and Ni grains were coarsened, which softened deposits.
