Modification of the microstructure of Nd15Fe77B8 alloy by controlled solidification

The influence of solidification behavior on the microstructure, hydrogen absorption, and magnetic domains of Nd-Fe-B alloys has been investigated. Microstructural observations on ingots of Nd-Fe-B alloys solidified by horizontal and vertical float zoning techniques have allowed the phase distribution, grain size distribution, and the nature of the solid-liquid growth interface to be studied and compared with the as-cast microstructure. The nature of hydrogen absorption as observed by DTA (differential thermal analysis) is complex but may prove to be a useful phase analysis aid as well as a decrepitation route to produce single crystals from large-grained material.