The effect of Nb addition on environmental embrittlement of a Ni3(Si,Ti) alloy

The effect of Nb addition on the moisture-induced embrittlement of a Ni3(Si,Ti) alloy was investigated at room temperature by tensile test and SEM fractography. Embrittlement/ductility was assessed as functions of strain rate and environment. The Nb-containing second-phase dispersion was found to be effective in reducing the moisture-induced embrittlement of the Ni3(Si,Ti) alloy, while Nb as a solute in the Ll2 matrix was shown to enhance the moisture-induced embrittlement of the Ni3(Si,Ti) alloy. Possible mechanisms accounting for the beneficial effect of the Nb-containing second-phase dispersion on the moisture induced embrittlement of the Ni3(Si,Ti) alloy was discussed in terms of microstructural modification by the second-phase, hydrogen transportation kinetics and deformation properties in the constituent phases or L12 matrix/second-phase interface.