Mobility of Ni versus Zr in an amorphous Ni-Zr alloy

A method for determining the dominant diffusing constituent in a binary amorphous alloy is demonstrated with the Ni‐Zr system. Nickel is the dominant moving species in an amorphous Ni‐Zr alloy near the a‐Ni50Zr50 composition at 250 °C. In comparison to the Ni, the Zr has a negligible mobility under similar thermodynamic driving forces. Rutherford backscattering spectrometry is used to measure the change in the concentration of a thin film of Ni between thick amorphous layers. Based upon the change in the Ni profile, the diffusivity of Ni in an amorphous Ni‐Zr alloy is between 1×10−17 and 1×10−16 cm2/s at 250 °C.