Ta2C precipitation after low pressure carburizing of tantalum
Résumé
Low pressure carburizing cycles were carried out on tantalum samples. A Ta2C precipitates layer is present under
the TaC and Ta2C surface layers. As the TaC and Ta2C layers, the Ta2C precipitates layer (TPL) grows by carbon
diffusion in tantalum matrix. Specific zones with low precipitates content were observed at the bulk surface and
in the tantalum grain boundaries. Other zones with lower precipitates content are also present in carburized and
annealed samples. All the zones with low precipitates content are induced by the Ta2C precipitation mechanism
described by Dahmen et al. [1,2]. Indeed, Ta2C needs vacancies to precipitate. If vacancy sinks are present at the
bulk surface, at a grain boundary or in a dislocation, then Ta2C precipitation is highly reduced. Another effect of
the annealing treatment is an increase of the Ta2C precipitates layers growth rate.
Domaines
Matériaux
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