DYNAMIC EMBRITTLEMENT OF BORON-DOPED NI3AL ALLOYS AT 600-DEGREES-C

Boron-doped Ni//3Al alloys, with and without 0. 5 at. % Hf, were tensile tested in vacuum and in oxidizing environments at 600 degree C. Lower ductilities were observed in air. Tests of preoxidized specimens indicate that embrittlement is due to a dynamic effect simultaneously involving localized stress concentrations, elevated temperature, and gaseous oxygen. The oxygen embrittlement becomes less severe with a decrease in aluminum concentration from 24 to 21 at. %.