Suitability of Nd-Fe-B permanenet magnets for biomedical applications - a corrosion study

The present paper explains the suitability of a permanent magnetic alloy, Nd-Fe-B and efforts made to improve its corrosion resistance by the addition of alloying elements like Nb and Ga. The results revealed that gallium addition of 1at.% in association with dysprosium and cobalt has strong positive influence and reduces the corrosion rate of the base alloy, Nd-Fe-B considerably while 1at.% Nb addition increases the corrosion rate marginally in simulated body fluid environments. Though, the corrosion rate has reduced considerably by the addition of alloying elements, the corrosion rate is still high. The studies also showed that the degradation of alloys with and without alloying additions take place due to grain boundary corrosion. Finally, the importance of surface engineering techniques in combating corrosion is more effective than the technique of alloying addition in body fluid environments, without affecting the magnetic properties and thereby enhancing their exploitation and life, has been highlighted. (C) 2002 Elsevier Science B.V. All rights reserved.