Citation
Palacios García, Teresa and Reiser, J. and Hoffmann, J. and Rieth, M. and Hoffmann, A. and Pastor Caño, Jose Ignacio
(2015).
Microstructural and mechanical characterization of annealed tungsten (W) and potassium-doped tungsten foils.
"International Journal of Refractory Metals and Hard Materials", v. 48
;
pp. 145-149.
ISSN 0263-4368.
https://doi.org/10.1016/j.ijrmhm.2014.09.005.
Abstract
Here we show that potassium-doped tungsten foil should be preferred to pure tungsten foil when considering tungsten laminate pipes for structural divertor applications. Potassium-doped tungsten materials are well known from the bulb industry and show an enhanced creep and recrystallization behaviour that can be explained by the formation of potassium-filled bubbles that are surrounding the elongated grains, leading to an interlocking of the microstructure. In this way, the ultra-fine grained (UFG) microstructure of tungsten foil can be stabilized and with it the extraordinary mechanical properties of the foil in terms of ductility, toughness, brittle-to-ductile transition, and radiation resistance. In this paper we show the results of three-point bending tests performed at room temperature on annealed pure tungsten and potassium-doped tungsten foils (800, 900, 1000, 1100, 1200, 1300, 1400, 1600, 1800, 2000, 2200, and 2400 °C for 1 h in vacuum). The microstructural assessment covers the measurement of the hardness and analyses of fractured surfaces as well as a comparison of the microstructure by optical microscopy. The results show that there is a positive effect of potassium-doped tungsten foils compared to pure tungsten foil and demonstrate the potential of the doped foil