QUANTITATIVE-DETERMINATION OF LOW PHASE VOLUME FRACTION IN FERROSILICON ALLOYS BY THE RIETVELD PROFILE-REFINEMENT METHOD - NEUTRON-DIFFRACTION DATA COMPARED WITH OTHER METHODS

Neutron diffraction data collected from ferrosilicon alloy powders hav e been analysed using the Rietveld profile-refinement method in order to perform a quantitative determination of the phase volume fraction. The results obtained have been compared with those determined from oth er methods such as imaging analysis, chemical analysis and phase-diagr am calculation by a thermodynamic approach. For low phase volume fract ions, the Rietveld profile refinement of the neutron-powder-diffractom eter data gives results that are more accurate than those from imaging analysis and that are more representative at the ingot scale than tho se from chemical analysis, owing to the greater quantity of powder ana lysed. As concerns the thermodynamic calculations, two phase volume fr action determinations may be performed: quantitative, at equilibrium, and qualitative, out of equilibrium.