Mobility of nitrogen in ε-Fe3N below 150 °C: The activation energy for reordering

✍ Scribed by Andreas Leineweber

• Book ID: 103998307
• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 513 KB
• Volume: 55
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2007.08.020

✦ Synopsis

Previously quenched (from 573 K) e-iron nitride powder of a composition close to Fe 3 N, which shows partial disorder in the interstitial N superstructure, can be reordered by annealing between 373 and 408 K. The kinetics of the reordering can experimentally be traced by the axial ratio (c hcp /a hcp ), as measured by X-ray powder diffraction, and can be described by a first-order rate law for the time-dependence of (c hcp /a hcp ) with an Arrhenius-type temperature dependence of the rate constant. The determined activation energy of 144 ± 5 kJ mol À1 can be associated with specific jumps of N atoms from disorder to order sites. The order-of-magnitude of the preexponential factor of (7 ± 10) • 10 13 s À1 can be related with the vibration frequency of the N atom in an octahedral site.