HDDR processes in Nd16Fe76-xZrxB 8 alloys and the production of anisotropic magnets

The HDDR-behaviour of a series of as cast alloys given by the general formula Nd₁₆Fe_76-xB₈Zr_x (0⩽x⩽2.0) has been characterised by hydrogen DTA and resistivity studies, It was found that increasing values of x increased the temperature of disproportionation. Microstructural studies of the Nd ₁₆Fe_75.5Zr_0.5B₈ alloy showed that a Zr-Fe containing phase present at the grain boundaries in the cast and disproportionated material is transformed during recombination into a Nd-Zr-Fe containing phase. This work shows that it is possible to produce highly anisotropic HDDR material from a non-homogenised Nd₁₆Fe_75.5Zr_0.5B₈ cast alloy without any further additions such as Co or Ga. Under the conditions employed in these experiments it was found that the best properties were obtained for the Nd₁₆Fe_75.5B₈Zr_0.5 alloy with a B_r value in the easy direction of 1.03T and an _iH_c of 775 kA/m. The high degree of anisotropy was confirmed by optical microscopy (polarised light)