Quantitative Determination of Low-Phase Volume Fraction in Ferro-Silicon Alloys by the Rietveld Profile-Refinement Method. Neutron Diffraction Data Compared with Other Methods

Neutron diffraction data collected from ferrosilicon alloy powders have 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 other methods such as imaging analysis, chemical analysis and phase-diagram calculation by a thermodynamic approach. For low phase volume fractions, the Rietveld profile refinement of the neutron-powder-diffractometer data gives results that are more accurate than those from imaging analysis and that are more representative at the ingot scale than those from chemical analysis, owing to the greater quantity of powder analysed. As concerns the thermodynamic calculations, two phase volume fraction determinations may be performed: quantitative, at equilibrium, and qualitative, out of equilibrium.