WDX Analysis of Rapidly Quenched Nd-Fe-B Alloys with Ti + C Additives

 Quenched stoichiometric Nd-Fe-B alloys with Ti + C additives, which improve the hard magnetic properties, were investigated by EPMA technique. The exact quantitative wavelength dispersive analysis meets with two problems: the carbon blank value and the C-Kα line coincidence with Nd-Mγ, Nd-Mα and Nd-Mζ of higher diffraction orders. The carbon blank value depends on the special residual gas pressure in the recipient and was determined by repeated measurements of a carbon free iron reference specimen e.g. with subsequent corrections of the carbon content. The second problem can be solved by blanking out the Nd induced contribution to the C-Kα region by a differential detection mode. In this case an energy discriminator was used to set a lower and an upper level in order to suppress the neighbouring coincident lines. The optimized analysis allowed an exact determination of carbon content in all investigated phases.