Laser-equipped gas reaction chamber for probing environmentally sensitive materials at near atomic scale

TL;DR

This paper introduces a laser-equipped gas reaction chamber, the Reacthub, enabling atomic-scale analysis of environmentally-sensitive materials after thermochemical treatments in controlled gaseous atmospheres, with applications demonstrated on steel and oxide samples.

Contribution

The study presents a novel thermochemical reaction chamber that allows for in-situ treatment and ex-situ atomic-scale characterization of sensitive materials under controlled gas environments.

Findings

Successful detection of deuterium ingress in steel after gas charging.

Rapid nanoscale reduction of wuestite under thermochemical treatment.

Demonstration of capturing transient states for atomic-scale analysis.

Abstract

Numerous metallurgical and materials science applications depend on quantitative atomic-scale characterizations of environmentally-sensitive materials and their transient states. Studying the effect upon materials subjected to thermochemical treatments in specific gaseous atmospheres is of central importance for specifically studying a material's resistance to certain oxidative or hydrogen environments. It is also important for investigating catalytic materials, direct reduction of an oxide, particular surface science reactions or nanoparticle fabrication routes. This manuscript realizes such experiments upon a thermochemical reaction chamber called the Reacthub and allows for transferring treated materials under cryogenic & ultrahigh vacuum workflow conditions for characterisation by either atom probe or scanning Xe+/electron microscopies. Two examples are discussed in the present study. One protocol was in the deuterium gas charging (25 kPa D2 at 200 {\deg}C) of a high-manganese twinning-induced-plasticity steel and characterization of the ingress and trapping of hydrogen at various features (grain boundaries in particular) in efforts to relate this to the steel's hydrogen embrittlement susceptibility. Deuterium was successfully detected after gas charging but most contrast originated from the complex ion FeOD+ signal and the feature may be an artefact. The second example considered the direct deuterium reduction (5 kPa D2 at 700 {\deg}C) of a single crystal wuestite sample, demonstrating that under a standard thermochemical treatment causes rapid reduction upon the nanoscale. Further studies are required for complete confidence about these phenomena, but these experiments successfully demonstrate that how an ex-situ thermochemical treatment can be realised that captures environmentally-sensitive transient states that can be analysed by atomic-scale by atom probe microscope.