Behavior of the Electroless Composite Films Plated from a Ni‐P Bath with Metallic Dispersion of Zr and Nb Powders

Abstract

An electroless Ni‐Zr‐P composite film and a Ni‐Nb‐P composite film were plated and their heat‐treating behaviors were investigated. The addition of 20g dm−3 of metallic powder resulted in a composite film that contained 21.2 weight percent (w/o) of Zr, [13.8 atom percent (a/o)], or 4.8 w/o of Nb, (2.9 a/o), respectively. Both metallic powders were dispersed uniformly throughout the films. The metallic Ni formed by the crystallization of the Ni‐P matrix diffused into the metallic powders, and the amorphous Ni‐Zr and Ni‐Nb phases were formed by heat‐treatment at 500° or 300°C. Some parts of the amorphous Ni‐Zr phases and the metallic Ni phases combined to form intermetallic compounds by heat‐treatment at 600°C. The nickel‐rich parts of the amorphous Ni‐Nb phase were converted into a metastable Ni‐Nb phase (ζ phase) or a Ni‐Nb solid solution by heat‐treatment at 700°C. The longer heating time at 400°C increased the amount of the Ni‐Zr amorphous phase: however, it decreased the reactivity of the amorphous Ni‐Zr phase. The same heat‐treatment of 400°C did not give the considerable change on the amorphous Ni‐Nb phase.