SIMS measurement of oxygen content in γ-TiAl single crystals and polycrystalline alloys with Nb addition

The oxygen content of binary Ti45Al55 and ternary Ti44Al52Nb4 single crystals and polycrystalline alloys was quantified with secondary ion mass spectrometry (SIMS) using Cs+ primary ions. The SIMS measurements were calibrated with respect to concentration and depth scale using oxygen implanted samples. The measurements revealed considerably lower oxygen content in the ternary alloy indicating a protecting impact of the Nb addition in grain boundaries against oxygen contamination. The relative strong surface oxide layer thickness of the investigated samples was determined to about 1 μm.