Irradiation hardening in unalloyed and ODS molybdenum during low dose neutron irradiation at 300°C and 600°C

The change in the hardness of LCAC, TZM, and ODS molybdenum in the post-irradiated and annealed conditions

“…For these irradiations, the same DBTT of 800°C was observed for ODS, LCAC, and TZM [23,24]. High purity molybdenum and ODS molybdenum in the as-worked condition have exhibited lower DBTT values of 450°C and À50°C for irradiations at 300°C and 600°C, respectively, to much lower fluences (1.29-0.01 dpa-Mo) than obtained in this work [26]. This indicates higher purity and increased dislocation density can provide improved resistance to irradiation embrittlement and less hardening for low fluence irradiations [26].…”

“…High purity molybdenum and ODS molybdenum in the as-worked condition have exhibited lower DBTT values of 450°C and À50°C for irradiations at 300°C and 600°C, respectively, to much lower fluences (1.29-0.01 dpa-Mo) than obtained in this work [26]. This indicates higher purity and increased dislocation density can provide improved resistance to irradiation embrittlement and less hardening for low fluence irradiations [26]. Irradiation at temperatures of 800°C or higher, where the point defects have greater mobility, generally produces a lower number density of coarse voids that result in substantially less hardening and little embrittlement in any of the molybdenum materials studied [23,24].…”

“…This leads to an increase in the Ductile to Brittle Transition Temperature (DBTT). Wrought molybdenum alloys with fine, elongated grains, such as ODS molybdenum [24,26] or high-purity molybdenum [21,26], have exhibited resistance to irradiation embrittlement. A room-temperature DBTT was observed for 600°C irradiated ODS that is lower than the DBTT of 300°C and 700°C observed for LCAC and TZM, respectively, irradiated under the same conditions [23,24].…”

“…Many authors have studied the change in defect density during post-irradiated annealing using hardness and electrical resistivity measurements [3,[6][7][8][9][10][11][12][13]18,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. These studies have mainly used electrical resistivity methods while the studies that have utilized hardness measurements are generally conducted at a single irradiation temperature and single neutron fluence.…”

Evaluations of Mo-alloy for light water reactor fuel cladding to enhance accident tolerance

“…An extensive test program was undertaken by Bettis and Oak Ridge National Laboratories to evaluate the irradiation properties of various Mo-alloys in coupon forms for potential space reactor fuel material applications [5,6]. Thin wall Mo-alloy cladding suitable for LWR applications was not previously available.…”