[1L01-05] Refractory Structural Materials

[1L01] Effect of titanium concentration on tensile properties of low-activation vanadium alloys absorbing impurity nitrogen

*Kazuki Saito¹, Makoto Kobayashi^1,2, Jingjie Shen², Gaku Yamazaki¹, Takuya Nagasaka^1,2, Valentyn Tsisar³, Takeo Muroga^1,2 (1. SOKENDAI, 2. NIFS, 3. SCK・CEN)

Keywords:Fusion reactor structural material, Vanadium alloy, Scavenging effect, Mechanical properties

Low-activation vanadium alloys, such as V-4Cr-4Ti, embrittle by solid solution hardening because impurity nitrogen transports from liquid lithium breeder to the alloy. Titanium, one of the alloying elements, forms precipitates with nitrogen and suppresses the embrittlement, but the concentration should be reduced due to radioactivation. The present study evaluated the correlation between nitrogen diffusion, nitrogen precipitation behaviors, and mechanical properties. In order to simulate the nitrogen transport, a nitrogen gas was exposed at 650 °C and 0.066 atm for 25 hours. Yield behavior and elongation remained after nitrogen exposure at 3 mass% or higher of titanium concentration. All the alloys had ductile / brittle mixed fracture surfaces, and the ratio of brittle fracture surface decreased due to titanium concentration increased.