Microstructural study of the NbC to G-phase transformation in HP-Nb alloys. Vaché, N., Steyer, P., Duret-Thual, C., Perez, M., Douillard, T., Rauch, E., Véron, M., Renou, G., Dupoiron, F., Augustin, C., & Cazottes, S. Materialia, 9:100593, March, 2020.
Microstructural study of the NbC to G-phase transformation in HP-Nb alloys [link]Paper  doi  abstract   bibtex   
The microstructure of a centrifugally cast HP alloy was studied in its as-received state and after ageing at 900 °C. A multi-scale approach combining X Ray Diffraction (XRD), advanced electron microscopy modes (scanning and transmission electron microscopies (SEM, TEM), together with focused ion beam/SEM nanotomography (FIB-nt)) has been carried out to characterize the evolution of niobium carbides during ageing. After thermal treatment, the carbides exhibit a complex microstructure, consisting of a core of untransformed NbC, an intermediate layer of G-phase (Ni16Nb6Si7) with embedded nanometric titanium carbide precipitates, and an outer shell of alternating chromium carbides Cr23C6 and G-phase. A simple diffusion model was used to explain the faster external growth of G-phase compared to the internal NbC dissolution, and to determine a diffusion coefficient of niobium in the G-phase at 900 °C.
@article{vache_microstructural_2020,
	title = {Microstructural study of the {NbC} to {G}-phase transformation in {HP}-{Nb} alloys},
	volume = {9},
	issn = {2589-1529},
	url = {http://www.sciencedirect.com/science/article/pii/S2589152920300107},
	doi = {10.1016/j.mtla.2020.100593},
	abstract = {The microstructure of a centrifugally cast HP alloy was studied in its as-received state and after ageing at 900 °C. A multi-scale approach combining X Ray Diffraction (XRD), advanced electron microscopy modes (scanning and transmission electron microscopies (SEM, TEM), together with focused ion beam/SEM nanotomography (FIB-nt)) has been carried out to characterize the evolution of niobium carbides during ageing. After thermal treatment, the carbides exhibit a complex microstructure, consisting of a core of untransformed NbC, an intermediate layer of G-phase (Ni16Nb6Si7) with embedded nanometric titanium carbide precipitates, and an outer shell of alternating chromium carbides Cr23C6 and G-phase. A simple diffusion model was used to explain the faster external growth of G-phase compared to the internal NbC dissolution, and to determine a diffusion coefficient of niobium in the G-phase at 900 °C.},
	language = {en},
	urldate = {2020-02-05},
	journal = {Materialia},
	author = {Vaché, N. and Steyer, P. and Duret-Thual, C. and Perez, M. and Douillard, T. and Rauch, E. and Véron, M. and Renou, G. and Dupoiron, F. and Augustin, C. and Cazottes, S.},
	month = mar,
	year = {2020},
	keywords = {Advanced material characterization, Ageing, G-phase, HP-Nb alloy, Microstructure, NbC},
	pages = {100593}
}

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