INFLUENCE OF THE TIME OF MILLING ON THE MICROSTRUCTURE OF FE_(77)ND_(15)B_8 ALLOY SUBMITTED TO HIGH ENERGY BALL MILLING

摘要

Several works in recent years reported on the influence of milling conditions on the microstructure of Fe-Nd-B based alloys. Under milling it is observed disordering of the Fe_(14)Nd_2B compound for small milling times or milling under small collision energy, and for longer times or greater collision energy, a disproportionation of the compound into a-Fe and an amorphous phase is observed. After a low temperature annealing, the compound is recovered. In the literature, as a qualitative measure of the milling energy, it is quoted the ratio of the milling balls mass to the sample mass, and this ratio usually is in the interval from 4 up to 20. In this work we report the results of milling the commercial composition alloy at different times of milling with the ratio of ball to mass being 850:1, and the behavior of the resulting powders under heat-treatments.