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Continuous and Discontinuous αTi Layers Between Grains of β(Ti,Co) Phase

Continuous and Discontinuous αTi Layers Between Grains of β(Ti,Co) Phase The microstructure of Ti-Co polycrystals with 1.6 and 3.2 at.% Co has been studied between 690 and 810 °C after long anneals (720-860 h) in the αTi+β(Ti,Co) two-phase area of the Ti-Co phase diagram. It has been observed that depending on the annealing temperature and GB energy, the αTi phase forms either chains of separated lens-like precipitates or continuous uniform layers along β(Ti,Co)/β(Ti,Co) GBs. In other words, β(Ti,Co)/β(Ti,Co)GBs completely or partially wetted by the αTi phase were observed. At 690 °C, slightly above eutectoid temperature T et = 685 °C, the portion of the completely wetted β(Ti,Co)/β(Ti,Co) GBs is 25% for the Ti-1.6 at.% Co alloy and 60% for the Ti-3.2 at.% Co alloy. It increases with increasing temperature and reaches the maximum of 80% for the Ti-1.6 at.% Co alloy at 780 °C and of 75% for the Ti-3.2 at.% Co alloy at 750 °C. At 810 °C, i.e., close to the upper border of the αTi + β(Ti,Co) two-phase area of the Ti-Co phase diagram, the portion of the completely wetted β(Ti,Co)/β(Ti,Co) GBs drops down to 40% for the Ti-1.6 at.% Co alloy and 20% for the Ti-3.2 at.% Co alloy. Thus, it has been observed for the first time, that the portion of grain boundaries completely wetted by the layers of a second solid phase can non-monotonously depend on the temperature. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Materials Engineering and Performance Springer Journals

Continuous and Discontinuous αTi Layers Between Grains of β(Ti,Co) Phase

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References (47)

Publisher
Springer Journals
Copyright
Copyright © 2013 by ASM International
Subject
Material Science; Characterization and Evaluation of Materials; Tribology, Corrosion and Coatings; Quality Control, Reliability, Safety and Risk; Engineering Design
ISSN
1059-9495
eISSN
1544-1024
DOI
10.1007/s11665-013-0789-3
Publisher site
See Article on Publisher Site

Abstract

The microstructure of Ti-Co polycrystals with 1.6 and 3.2 at.% Co has been studied between 690 and 810 °C after long anneals (720-860 h) in the αTi+β(Ti,Co) two-phase area of the Ti-Co phase diagram. It has been observed that depending on the annealing temperature and GB energy, the αTi phase forms either chains of separated lens-like precipitates or continuous uniform layers along β(Ti,Co)/β(Ti,Co) GBs. In other words, β(Ti,Co)/β(Ti,Co)GBs completely or partially wetted by the αTi phase were observed. At 690 °C, slightly above eutectoid temperature T et = 685 °C, the portion of the completely wetted β(Ti,Co)/β(Ti,Co) GBs is 25% for the Ti-1.6 at.% Co alloy and 60% for the Ti-3.2 at.% Co alloy. It increases with increasing temperature and reaches the maximum of 80% for the Ti-1.6 at.% Co alloy at 780 °C and of 75% for the Ti-3.2 at.% Co alloy at 750 °C. At 810 °C, i.e., close to the upper border of the αTi + β(Ti,Co) two-phase area of the Ti-Co phase diagram, the portion of the completely wetted β(Ti,Co)/β(Ti,Co) GBs drops down to 40% for the Ti-1.6 at.% Co alloy and 20% for the Ti-3.2 at.% Co alloy. Thus, it has been observed for the first time, that the portion of grain boundaries completely wetted by the layers of a second solid phase can non-monotonously depend on the temperature.

Journal

Journal of Materials Engineering and PerformanceSpringer Journals

Published: Nov 26, 2013

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