THE EFFECT OF HEAT TREATMENT ON THE PROPERTIES OF HOT FORGED AND HOT ROLLED Pr-Fe-B MAGNETS
Abstract
Ingots of the Pr17Fe76.5B5Cu1.5 alloy with columnar structure were hot forged and hot rolled in the semi-solid temperature range with the aim to obtain oriented structures. It was found that the hot forged magnets had higher degree of texture development reflected in elevated values of the remanence. On the other hand the rolled magnets exhibited better coercivity since during the grain refinement the repeated passes resulted in more rounded grain shape which in turn partially limited their alignment and as a result lower remanences were obtained. The post-deformation heat treatment at 1000?C resulted in a slight remanence increase in both hot forged and hot rolled magnets, caused by the dissolution of small misoriented grains. The treatment of the as-deformed magnets at 520?C/1h resulted in a significant coercitivity increase in both deformation modes, being this increase more pronounced in the forged material. After the combined heat treatment of 1000?C/5h + 520?C/1h both the forged and rolled magnets increased their coercivity to about 940 kA/m.
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