Compositions of amorphous NiFeP alloy surfaces

Abstract

X-ray photoelectron spectroscopy was applied for a quantitative determination of the composition and thickness of the surface film and the composition of the alloy surface immediately under the surface film on melt-span amorphous Ni 80− x Fe x P 20 alloys containing 0–80 at.% Fe after different treatments. Mechanical polishing in cyclohexane at room temperature led to the formation of an iron-rich and nickel- and phosphorus-deficient surface film along with the nickel-rich underlying alloy surface. On the specimens exposed to air after crystallization in a vacuum of about 10 Pa at 870 K and subsequent heating in hydrogen gas of 1 MPa at 500 K, the surface film was rich with iron ions and the underlying alloy surface was deficient of nickel and phosphorus. The air-exposed specimens, after heat treatment in hydrogen gas at 500 K, possess the iron-rich surface film and the underlying alloy surfaces of intermediate composition between those formed by the former two treatments. Argon ion etching results in the nickel- and phosphorus-deficient metal surface due to different sputtering yields of alloy constituents.