Microstructure and cyclic oxidation behavior of W–Cr alloys prepared by sintering of mechanically alloyed nanocrystalline powders

Sintering and cyclic oxidation behavior of nanostructured W–Cr alloys having 30, 50 or 60 at.% Cr, prepared through mechanical alloying of elemental blends have been investigated. Relative density of 96–97.5% could be achieved by sintering at 1700 °C. X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy have shown the presence of W-rich and Cr-rich phases in sintered alloys. The oxidation resistance during exposure at 800 °C is found as the highest in the W _0.4Cr _0.6 alloy, while that at 1000 °C and 1200 °C appears to be the best for the W _0.5Cr _0.5 alloy. Relatively finer and more uniform distribution of the Cr-rich phase in microstructure of the W _0.5Cr _0.5 alloy appears to be responsible for its superior oxidation resistance. The Cr ₂O ₃ is found to be primarily responsible for protection against oxidation at 800 °C, while the formation of Cr ₂WO ₆ appears to have more significant role at ≥ 1000 °C.