Abstract
Nd–Fe–B alloys powdered by hydrogenation and mechanical grinding were oxidised at room temperature in ambient air. Changes in the X-ray spectra of the powder at the subsequent stages of the oxidation are explained by the progressive absorption of water molecules from ambient air to form structurally imperfect Nd(OH) 3 and the subsequent improvement of the hydroxide structure. The structural imperfectness of Nd(OH) 3 results in a very low intensity of the hydroxide spectra even at advanced stages of oxidation. This means either that the hydroxide is composed of very fine grains and/or that its structure is amorphous. We observed the similar improvement of the structure with time for hydroxides produced by oxidation of the hydrogenated Nd–Fe–B and NdH x . It is well established that the oxidation proceeds much slower in the virgin Nd–Fe–B powder than in the hydrogenated one. We present evidence that the rate of the oxidation process can be controlled by the amount of hydrogen absorbed by the alloy. We also show that the oxidation curves of the partially hydrogenated samples can be decomposed into the oxidation curves of fully hydrogenated and not hydrogenated samples.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.