Analysis of hydrogen distribution on Mg–Ni alloy surface by scanning electron-stimulated desorption ion microscope (SESDIM)

Hydrogen distribution and behavior on a Mg–Ni alloy surface are studied by using a time-of-flight electron-stimulated desorption (TOF-ESD) microscopy and a scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX). The desorbed hydrogen ions are energy-discriminated and distinguished into two characters in the adsorbed states, which belong to Mg2Ni grains and the other to oxygen-contaminated Mg phase at the grain boundaries. Adsorbed hydrogen is found to be stable up to 150 °C, but becomes thermally unstable around at 200 °C.