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

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.