The structure and microhardness of Ni-Fe-P and Ni-Fe-P-B alloy deposits prepared by electroless plating

摘要

The structures of ternary Ni-Fe-P and quaternary NiFe-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℃ produced structural changes. The microhardness of these deposits increased when the heat treatment temperature was 400℃ or below, and is shown to be related to the precipitation of Ni{sub}3P, Fe{sub}3P and Fe{sub}2B phases within the Ni-Fe solid solution matrix. When the heat treatment temperature was 500℃ or above, Ni{sub}3P, Fe{sub}3P, Fe{sub}2B particles and Ni, Fe grains were coarsened, which softened the deposits. Adding trace amounts of KBH{sub}4 can cause an incremental change in microhardness heat treatment above 300℃. Below 300℃, 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.