Cube textured Ni–3 at.% W tapes were heated to temperatures in the range800–1200 °C in flowing oxygen and either air-quenched or held for 1 h and furnacecooled. Cross-sectional backscattered electron images (BSEIs) and energydispersive x-ray (EDX) analysis showed the formation of the ternary oxideNiWO4 at temperaturesgreater than 1000 °C in addition to the usual NiO. The nickel tungstate phase appeared first as a layer at themetal/NiO interface and then as internal oxides within the substrate. At sometemperatures, the presence of this phase was observed to cause buckling and catastrophicspallation of the oxide.