Phase transformations and structure-property relationships in a rapidly solidified Ni-Al-Mo alloy
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In Part I the complex phase transformations occurring on ageing a melt-spun Ni-Al-Mo-V-Re alloy were determined by transmission electron microscopy (TEM). In the present paper, electrical resistivity and microhardness measurements on the aged, melt-spun ribbon are reported and correlated with the TEM studies. An initial increase in electrical resistivity on ageing corresponds to the spinodal ordering transformation. This is followed by precipitation of α(Mo). This also gives rise to an increase in microhardness with ageing time. The activation energy for this process was determined to be 270.8 kJ mol−1, corresponding to the volume diffusion of Mo in Ni. At long ageing times the electrical resistivity reaches a constant value and the microhardness decreases as the precipitates coarsen and a discontinuous precipitation reaction takes place.
KeywordsPolymer Precipitation Electron Microscopy Transmission Electron Microscopy Activation Energy
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