HDDR processes in Nd/sub 16/Fe/sub 76-x/Zr/sub x/B/sub 8/ alloys and the production of anisotropic magnets

The HDDR-behaviour of a series of as cast alloys given by the general formula Nd/sub 16/Fe/sub 76-x/B/sub 8/Zr/sub x/ (0/spl les/x/spl les/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/sub 16/Fe/sub 75.5/Zr/sub 0.5/B/sub 8/ 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 Nd/sub 16/Fe/sub 75.5/Zr/sub 0.5/B/sub 8/ 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 Nd/sub 16/Fe/sub 75.5/B/sub 8/Zr/sub 0.5/ alloy with a B/sub r/ value in the easy direction of 1.03T and an /sub i/H/sub c/ of 775 kA/m. The high degree of anisotropy was confirmed by optical microscopy (polarised light).