Eur. Phys. J. AP 9, 205-213 (2000)
https://doi.org/10.1051/epjap:2000106

Formation of rare earth hydroxide nanotubes and whiskers as corrosion product of LaNi₅-type alloys in aqueous KOH

¹ Centre d'Études de Chimie Métallurgique, CNRS, 15 rue G. Urbain, 94407 Vitry-sur-Seine, France
² SAFT, Direction de la Recherche, route de Nozay, 91460 Marcoussis, France

Corresponding author: backhaus@glvt-cnrs.fr

Received: 15 June 1999
Revised: 18 November 1999
Accepted: 23 November 1999
Published online: 15 March 2000

Abstract

Mm(OH)₃ (Mm = mischmetal) single crystalline needles with [001] growth axis form upon exposure of MmNi₅-substituted alloys to aqueous KOH. Crystal structure, chemical composition and morphology of the needles are studied by means of scanning electron microscopy and quantitative transmission electron microscopy. The needles can be either solid (whiskers) or hollow (nanotubes). Their morphology and growth kinetics are studied as a function of immersion temperature, stirring rate of the aqueous KOH electrolyte and presence of tracer. Based on the observations, a model mechanism is developed for their growth.