The Study of Defects in Quenched Nickel

Quenched nickel foils are investigated by electrical resistivity measurements, X‐ray small‐angle scattering and transmission electron microscopy. A marked dependence of the annealing behaviour on the purity of the specimens and the quenching atmosphere is observed. The quenched‐in vacancy concentrations are rather low, particularly in pure specimens where the total quenched‐in vacancy concentration is less than 5 × 10 −6 . In pure specimens one recovery stage only, centred at about 110°C, is observed between room temperature and 750°C. In less pure specimens a similar recovery stage is followed by a pronounced stage IV recovery (270°C) and a complex annealing behaviour above 400°C. The migration energies of mono‐ and divacancies are determined as E 1V M = (1.4±0.05) eV and E 2V M ⪆ (0.72±0.07) eV respectively. The divacancy binding energy is estimated as E 2V M > 0.23 eV. This rather large value is thought to be responsible for substantial vacanxcy losses during quenching.