Kinetics of the nitridation of dysprosium during mechanochemical processing

• Published in: Journal of alloys and compounds 2015-01, Vol.620, p.413-420
• Main Authors: Alanko, Gordon A., Osterberg, Daniel D., Jaques, Brian J., Hurley, Michael F., Butt, Darryl P.
• Format: Article
• Language: English
• Subjects: Alloys; Ball mills; Constraining; Dysprosium; Gas-solid reactions; High energy ball milling; Mathematical models; Mechanochemistry; Nitrides; Rare earths; Reaction kinetics; Surface chemistry
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.09.109

•DyN was mechanochemically synthesized by milling pure metal under nitrogen.•Temperature and pressure were monitored to investigate reaction progress.•The effects of metal adhered to media on the impact energetics was measured.•The reactive milling kinetics are described in terms of reactive surface formation. Dysprosium nitride was synthesized by the reactive milling of the rare earth metal under 400kPa nitrogen gas in a planetary ball mill. The nitrogen consumption rate was calculated from in situ temperature and pressure measurements to find the reaction extent as a function of milling time at milling speeds from 350 to 650rpm. The results are analyzed in terms of a fundamental milling dynamics model in which the input milling energy is the primary driving force for reaction and the rate limiting step of the nitridation kinetics is the formation of chemically active surfaces. The model differs from traditional gas–solid reactions which are often limited by diffusion of a species through a surface layer or by dissociation of the gas molecule. These results give fresh insight into reactive gas–solid milling kinetics.