Journal of the Japan Society of Powder and Powder Metallurgy

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Manganese bearing wustite containing MnO up to 16 mol % were prepared by powder metallurgical method as was previously reported, and their semiconductive properties were pursued.
The Neel point decreased and thermoelectric power increased with the increase of MnO content. Within the temperature range under survey, all specimens were p-type semiconductors and the activation energy for electric conduction was calculated to be 1.1-1.3×10^-1 eV below the Neel point and that of upper to be 0.6-0.8×10^-1eV.
From the thermomagnetic measurements it was found that the temperature at which thermal decomposition of the quenched specimen took place in reheating decreased as the content of MnO increased. The Curie point of the decomopsed spinel phase was also decreased as the increase of MnO content.
From these results, in addition to the results described in the first paper, some points were noticed about the distribution of iron and manganese ions in the wustite phase. That is, spinel like skeleton having n-type behavior were presumed to exist superposed on the wustite lattice locally, especially near grain boundary, and this skeleton was seemed to accelerate the thermal disintegration.

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The binder phase (γ) of WC-Co type sintered alloys has been accepted as fcc metal. However, it was found that under the external stresses the binder phase of the alloys in particular with high carbon content transforms easily into ε phase (hcp) at low temperatures. The signficant influences of the transformation on the low temperature properties such as elastic and plastic behaviors, strength, ductility, as well as various physical properties including lattice defects have been suggested.

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