Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5458245 | Journal of Alloys and Compounds | 2017 | 11 Pages |
Abstract
Three cast alloys with compositions of Co-9Al-8W-0.1B, Co-9Al-9W-0.1B and Co-9Al-11W-0.1B (all atomic percent) were aged at 900 °C for 200 h, 500 h, 1000 h, 2000 h, 5000 h and 10000 h to investigate the thermal stability of L12 type γâ²-Co3(Al,W) precipitates. The microstructure during the extended ageing process was observed by Scanning and Transmission Electron Microscopy in order to investigate the evolution of the γ/γⲠtwo-phase microstructure and the formation of any additional phases. It was found after 5000 h ageing that four phases, γ, γâ², D019 and B2, were present within the microstructure as identified by X-ray Diffraction combined with Transmission Electron Microscopy and Electron Backscattered Diffraction. The γⲠprecipitates coarsened according to modified Lifshitz, Slyozov and Wagner theory generally. The fraction of γⲠphase decreased while that of D019 phase increased contrarily. The phase transformation process from γâ²-L12 to D019 was illustrated by Transmission Electron Microscopy. Stacking faults were identified as the initial step of the decomposition of the γⲠphase.
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
Yuzhi Li, Florian Pyczak, Michael Oehring, Li Wang, Jonathan Paul, Uwe Lorenz, Zekun Yao,