Abstract
This paper describes the effect of grain shape on environmental embrittlement in boron-doped Ni3Al (24 at. % Al). The alloy showed severe embrittlement when tested at 600 and 760 °C in air. The embrittlement can be alleviated by control of grain shape, and the material with a columnar-grained structure produced by directional levitation zone remelting shows good tensile ductilities when tested in oxidizing environments. The columnar-grained structure with vertical grain boundaries minimizes the normal stress and consequently suppresses nucleation and propagation of cracks along the boundaries.