Deformation mechanisms in a Co-rich nickel based superalloy with different size of γ׳ precipitates

A Co-rich nickel based superalloy with different size of γ׳ precipitates is obtained through varied aging time. Microstructures after tensile deformation at intermediate temperature are investigated by transmission electron microscopy. With the increasing γ׳ precipitate size, the deformation mode of the alloy changes from cutting the precipitates by 1/2〈110〉 dislocation pairs to cutting by 1/6〈112〉 partial dislocations. Microtwinning occurs with high density of stacking faults, attributing to the low stacking fault energy of the alloy. With further increase of the precipitate size, the alloy starts to be deformed by Orowan bypassing mechanism.