The Structure & Microhardness Of Ni-Fe-P & Ni-Fe-P-B Alloy Deposits Prepared by Electroless Plating

摘要

The structures of ternary Ni-Fe-P and quaternary Ni-Fe-P-B electroless alloy deposits produced at various sodium hypophosphite concentrations and heat treatment temperatures were studied by X-ray diffraction analysis. Heating these deposits from 200 to 700 deg C produced structural changes. The microhardness of these deposits increased when the heat treatment temperature was 400 deg C or below, and is shown to be related to the precipitation of Ni_3P, Fe_3P and Fe_2B phases within the Ni-Fe solid solution matrix. When the heat treatment temperature was 500 deg C or above, Ni_3P, Fe_3P, Fe_2B particles and Ni, Fe grains were coarsened, which softened the deposits. Adding trace amounts of KBH_4 can cause an incremental change in microhardness heat treatment above 300 deg C. Below 300 deg C, its effects on hardness were not obvious. The observation was believed to be correlated with the crystallization phases of B and Ni-Fe solid solution matrix.