Probing the correlation between phase evolution and growth kinetics in the oxide layers of tungsten using Raman spectroscopy and EBSD

TL;DR

This study investigates how substrate orientation affects the phase evolution and growth kinetics of tungsten oxide layers formed during annealing, using Raman spectroscopy and EBSD to analyze structural variations relevant for fusion reactor materials.

Contribution

It provides new insights into the correlation between phase evolution and growth kinetics of tungsten oxides influenced by substrate orientation during annealing.

Findings

Preferential oxidation on {111} planes initially

Dynamic change in oxide phase composition

Oxide growth kinetics influenced by phase evolution

Abstract

Tungsten, a plasma-facing material for future fusion reactors, may be exposed to air during abnormal operation or accidents. Only limited information is available on the evolution of related oxide phases. This work addresses the effect of substrate orientation on structural variations of tungsten oxides. Annealing experiments in an argon-oxygen atmosphere have been conducted at T = 400 {\deg}C under varying oxygen partial pressure and oxidation time. A combination of EBSD, Raman spectroscopy and confocal microscopy shows preferential oxidation initially on {111} base material planes. The oxide scale changes its phase composition dynamically, influencing the kinetics of its growth.