Imperial College London
Portrait Picture

ProfessorDavidDye

Faculty of Engineering, Department of Materials

Professor of Metallurgy
 
 
 
//

Contact

 

+44 (0)20 7594 6811david.dye

 
 
//

Location

 

1.09GoldsmithSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{vorontsov:2016:10.1016/j.actamat.2016.08.023,
author = {vorontsov, VA and Barnard, JS and Rahman, KM and Yan, H and Midgley, PA and Dye, D},
doi = {10.1016/j.actamat.2016.08.023},
journal = {Acta Materialia},
pages = {14--23},
title = {Coarsening behaviour and interfacial structure of γ′ precipitates in Co-Al-W based superalloys},
url = {http://dx.doi.org/10.1016/j.actamat.2016.08.023},
volume = {120},
year = {2016}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This work discusses the effects of alloying on the coarsening behaviour of the L12 ordered γ′ phase and the structure of the γ/γ′ interfaces in three Co-Al-W base superalloys aged at ∼90 °C below the respective solvus temperatures: Co-7Al-7W, Co-10Al-5W-2Ta and Co-7Al-7W-20Ni (at.%). The coarsening kinetics are adequately characterised by the classical Lifshitz-Slyozov-Wagner model for Ostwald ripening. Co-7Al-7W exhibited much slower coarsening than its quaternary derivatives. Alloying can be exploited to modify the coarsening kinetics either by increasing the solvus temperature by adding tantalum, or by adding nickel to shift the rate controlling mechanism towards dependence on the diffusion of aluminium rather than tungsten. Lattice resolution STEM imaging was used to measure the widths of the order-disorder (structural) and Z-contrast (compositional) gradients across the γ/γ′ interfaces. Similarly to nickel base superalloys, the compositional gradient was found to be wider than the structural. Co-7Al-7W-20Ni had much wider interface gradients than Co-7Al-7W and Co-10Al-5W-2Ta, which suggests that its γ′ phase stoichiometry is less constrained. A possible correlation between temperature and misfit normalised r vs. t1/3 coarsening rate coefficients and the structural gradient width has also been identified, whereby alloys with wider interfaces exhibit faster coarsening rates.
AU  - vorontsov,VA
AU  - Barnard,JS
AU  - Rahman,KM
AU  - Yan,H
AU  - Midgley,PA
AU  - Dye,D
DO  - 10.1016/j.actamat.2016.08.023
EP  - 23
PY  - 2016///
SN  - 1359-6454
SP  - 14
TI  - Coarsening behaviour and interfacial structure of γ′ precipitates in Co-Al-W based superalloys
T2  - Acta Materialia
UR  - http://dx.doi.org/10.1016/j.actamat.2016.08.023
UR  - http://hdl.handle.net/10044/1/41639
VL  - 120
ER  -
Download