TY - BOOK
T1 - Impact of annealing at 1000°C in flowing He with low O2 concentration on the room temperature tensile properties of Mo alloys
AU - Dryepondt, Sebastien
AU - Willoughby, Adam
AU - Johnston, Brandon
PY - 2022
Y1 - 2022
N2 - NorthStar is developing an accelerator-based technology to produce the medical isotope Mo-99. A previous ORNL report (ORNL/SPR-2022/2490) studied the oxidation behavior of Mo in flowing He with low oxygen content at 800°C and 1000°C and it was shown that an O2 concentration lower than ~5ppm (μ1/1) is required to achieve acceptable oxidation rates for wrought or powder metallurgy (PM) Mo. Oxidation may also impact the mechanical properties of Mo and this report summarizes tensile results at room temperature on wrought and PM Mo before and after exposure at 1000°C in flowing He with O2 concentration varying from 1 to 15 ppm O2. It was found that oxidation at 1000°C results in a significant decrease of Mo strength and ductility with brittle intergranular fracture surfaces, likely due to the segregation of oxygen at grain boundaries. For the PM Mo material, the decrease in strength and ductility was also observed after annealing in vacuum at 1000°C, indicating that the diffusion of the oxygen trapped in the material pores to grain boundaries after 20-100h at 1000°C is sufficient to embrittle the material. Finally, initial results on actual aMo and high-density disks provided by NorthStar revealed the lack of ductility of the materials due to the specific disk microstructure.
AB - NorthStar is developing an accelerator-based technology to produce the medical isotope Mo-99. A previous ORNL report (ORNL/SPR-2022/2490) studied the oxidation behavior of Mo in flowing He with low oxygen content at 800°C and 1000°C and it was shown that an O2 concentration lower than ~5ppm (μ1/1) is required to achieve acceptable oxidation rates for wrought or powder metallurgy (PM) Mo. Oxidation may also impact the mechanical properties of Mo and this report summarizes tensile results at room temperature on wrought and PM Mo before and after exposure at 1000°C in flowing He with O2 concentration varying from 1 to 15 ppm O2. It was found that oxidation at 1000°C results in a significant decrease of Mo strength and ductility with brittle intergranular fracture surfaces, likely due to the segregation of oxygen at grain boundaries. For the PM Mo material, the decrease in strength and ductility was also observed after annealing in vacuum at 1000°C, indicating that the diffusion of the oxygen trapped in the material pores to grain boundaries after 20-100h at 1000°C is sufficient to embrittle the material. Finally, initial results on actual aMo and high-density disks provided by NorthStar revealed the lack of ductility of the materials due to the specific disk microstructure.
KW - 36 MATERIALS SCIENCE
U2 - 10.2172/1973347
DO - 10.2172/1973347
M3 - Commissioned report
BT - Impact of annealing at 1000°C in flowing He with low O2 concentration on the room temperature tensile properties of Mo alloys
CY - United States
ER -