Abstract
The kinetics of recrystallisation of cold rolled nickel (99.98% purity) have been investigated by means of in situ heating in a scanning electron microscope and quantitative post-mortem metallographic examinations as well as microhardness measurements. The specimens were deformed over a wide range of deformation ratio (ε = 0.25–1.12) and isothermally annealed at 455°C. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory has been tested, and it has beenfound that measured JMAK exponents (n = 1.3–2.1) are lower than those predicted theoretically and are strongly dependent on deformation ratio. Therefore, it is confirmed that the JMAK theory fails to apply to the recrystallisation of plastically deformed nickel. Two hypotheses, competition between recovery and recrystallisation and non-random distribution of nucleation sites, are discussed to explain the low values of the JMAK exponent.
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