Phase Characterization of Re-Based Diffusion Barrier Layer on Nb Substrate

Abstract

An electron microscopy phase characterization was carried out for a Re-based diffusion barrier layer, which was deposited on the Nb substrate used as an ultra high temperature material. The coating process produced three layers; an outer Cr(Re) layer, an intermediate Cr-Nb-Re layer, and an inner Nb(Re) layer. The Cr-Nb-Re layer is considered to act as a diffusion barrier layer between the substrate and the outer Cr(Re) reservoir layer. The Cr(Re) and Nb(Re) layers are in single phase with a similar bcc structures, but they are different in structure from the intermediate layer, which is composed of a dual phase of Re 63 Cr 20 Nb 17 with a cubic structure and Nb 42 Re 33 Cr 25 with a hexagonal structure determined by transmission electron microscopy (TEM) in this study.

Electrodeposition and the Optimization of Molybdenum Layer on Nb-Ti-Si Based Ultra-High Alloys from Aqueous Solution

“…However, it was detected that brighter and more integrated deposits were obtained on the Rhenium (Re) coated alloy compared with that gained on bare substrate macroscopically. Here Re was applied due to its favorable compatibility with both MoSi 2 and Nb and its rather high melting point, outstanding mechanical properties and electrical conductivity [21,22]. Coatings directly deposited on the substrate alloy were discontinuous and broken while adhering and unbroken molybdenum coatings without cracks were obtained on the Re-coated samples under the same deposition conditions from Fig.…”