In Situ Transmission Electron Microscopy Investigation of Continuous Precipitation of Ni 3Mo in a Superalloy Formed by Direct Current Magnetron Sputtering

Abstract

In Situ heating experiments explore a correlation between hexagonal close-packed (HCP) domains in sputter-deposited Ni-25Mo-8Cr films and the precipitation of HCP-type structures (Ni₃Mo). Dynamic observation of phase evolution in diffraction mode confirms that precipitation behavior in these defect-dense thin films is not merely kinetically accelerated; instead, the pathway is fundamentally altered. Short-range ordering (SRO) behavior was observed upon reaching 650ºC. SRO has been documented as part of the face-centered cubic (FCC)-precipitation pathway, but has not previously been reported for HCP-based precipitates. This effort provides evidence for continuous ordering of HCP-based precipitates from SRO domains in a mixed FCC-HCP metallic material.