Manufacturing and testing of self-passivating tungsten alloys of different composition

Calvo, A.; Pintsuk, G.; Greuner, H.; Koch, F.; García-Rosales, C.; Iturriza, I.; Ordás, N.; Sarbu, C.

doi:10.1016/j.nme.2016.06.002

Journal Article

FZJ-2017-06244

Manufacturing and testing of self-passivating tungsten alloys of different composition

Calvo, A. ; García-Rosales, C. (Corresponding author) ; Koch, F. ; Ordás, N. ; Iturriza, I. ; Greuner, H. ; Pintsuk, G.FZJ* ; Sarbu, C.

2016
Elsevier Amsterdam [u.a.]

Nuclear materials and energy 9, 422 - 429 (2016) [10.1016/j.nme.2016.06.002]

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Please use a persistent id in citations: http://hdl.handle.net/2128/15223 doi:10.1016/j.nme.2016.06.002

Abstract: Self-passivating tungsten based alloys for the first wall armour of future fusion reactors are expected to provide a major safety advantage compared to pure tungsten in case of a loss of coolant accident with simultaneous air ingress, due to the formation of a stable protective scale at high temperatures in presence of oxygen which prevents the formation of volatile and radioactive WO3.Bulk W-15Cr, W-10Cr-2Ti and W-12Cr-0.5Y alloys were manufactured by mechanical alloying followed by can encapsulation and HIP. This route resulted in fully dense materials with nano-structured grains. The ability of Ti and especially of Y to inhibit grain growth was observed in the W-10Cr-2Ti and W-12Cr-0.5Y alloys. Besides, Y formed Y-rich oxide nano-precipitates at the grain boundaries, and is thus expected to improve the mechanical behaviour of the Y-containing alloy. Isothermal oxidation tests at 800 ºC (1073 K) and oxidation tests under accident-like conditions revealed that the W-12Cr-0.5Y alloy exhibits the best oxidation behaviour of all alloys, especially in the accident-like scenario. Preliminary HHF tests performed at GLADIS indicated that the W-10Cr-2Ti alloy is able to withstand power densities of 2 MW/m2 without significant damage of the bulk structure. Thermo-shock tests at JUDITH-1 to simulate mitigated disruptions resulted in chipping of part of the surface of the as-HIPed W-10Cr-2Ti alloy. An additional thermal treatment at 1600 °C (1873 K) improves the thermo-shock resistance of the W-10Cr-2Ti alloy since only crack formation is observed.

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