Intermediate temperature embrittlement in high-purity Ni and binary Ni(Bi) alloy

The tensile ductility of high-purity Ni and binary Ni(Bi) alloy were studied in the temperature range of 400–850 °C. Ni(Bi) alloy shows evident intermediate temperature embrittlement with a minimum ductility between 700 and 750 °C, while high-purity Ni does not. It is concluded that this embrittlement must be an impurity effect. On the basis of quantitative estimates, the embrittlement is interpreted as being caused by thermo-induced non-equilibrium grain-boundary segregation of Bi.