Study of Secondary-Ion Emission during the Interaction of Zr2Fe Getter Alloy with Oxygen

Changes in the composition of chemical compounds on the surface of a polycrystalline Zr2Fe alloy sample upon its interaction with oxygen, as well as the effect of oxygen on the processes of alloy interaction with hydrogen are studied using the secondary ion mass spectrometry technique. The interaction of oxygen with the alloy sample is shown to cause the formation of a complex oxide structure containing zirconium, iron, and oxygen on the surface and in the surface region. The ratio of the number of oxygen atoms to that of metal atoms in the oxides increased with increasing oxygen partial pressure. When the alloy is exposed to a hydrogen-oxygen gas mixture, a chemical structure that includes oxides, hydrides and hydroxides of alloy components is formed on the surface. The amount and composition of the compounds formed depend on the ratio of the hydrogen and oxygen fractions in the gas mixture, although the formation of oxides prevails over the formation of hydrides. Hydrides of the alloy components, mainly zirconium hydrides, are formed on surface sites that are free from oxides and hydroxides. At a fixed value of the oxygen partial pressure, an increase in the hydrogen partial pressure results in an increase in the amount of hydrides at such free sites. The effect of oxygen on the hydrogen sorption kinetics by the Zr2Fe alloy consists in a decrease in the hydrogen-adsorption efficiency, due to the formation of oxides on the getter surface.