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

B. V. Cockeram; R. W. Smith; T. S. Byun; L. L. Snead

doi:10.1016/j.jnucmat.2009.04.025

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

B. V. Cockeram, R. W. Smith, T. S. Byun, L. L. Snead

Radiation Effects and Microstructural An

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Abstract

Hardness measurements were performed on wrought Low Carbon Arc Cast (LCAC), TZM, and Oxide Dispersion Strengthened (ODS) molybdenum in the post-irradiated and post-irradiated + annealed condition to determine the recovery kinetics. Irradiations performed in the High Flux Isotope Reactor (HFIR) at nominally 300 °C and 600 °C to neutron fluence levels that range from 10.5 to 246 × 10²⁴ n/m² (E > 0.1 MeV) resulted in relatively large increases in hardness (77-109%), while small increases in hardness (<18%) were observed for irradiations at 870-1100 °C. The hardness recovery for ODS and LCAC irradiated at 300 °C and 600 °C were shown to be complete at 980 °C and ≈ 1100-1250 °C, respectively. Isothermal annealing at 700 °C was used to determine the activation energy for recovery of LCAC and ODS (3.70-4.88 eV ± 0.28-0.77 eV), which is comparable to values reported in the literature for molybdenum vacancy self-diffusion. This suggests that recovery of LCAC and ODS is controlled by the solid-state diffusion of vacancies in the bulk, and that the finer grain size and particle size ODS does not affect this mechanism. TZM exhibited slower recovery kinetics, which can be explained by the solute atoms (titanium and zirconium) inhibiting vacancy diffusion.

Original language	English
Pages (from-to)	12-21
Number of pages	10
Journal	Journal of Nuclear Materials
Volume	393
Issue number	1
DOIs	https://doi.org/10.1016/j.jnucmat.2009.04.025
State	Published - Aug 15 2009

Funding

This work was supported by USDOE. The authors are grateful for the review and comments provided by J.E. Hack. The assistance of R.F. Luther and A.J Mueller in providing some of the LCAC and ODS molybdenum specimens used in this work is much appreciated. Thanks also to the following ORNL personnel for their contributions in completing irradiations and testing (A.L. Qualls, A.W. Williams, and J.L. Bailey). Irradiations were carried out in the High Flux Isotope Reactor, a Department of Energy Office of Science User Facility.

Funders	Funder number
U.S. Department of Energy

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

abstract = "Hardness measurements were performed on wrought Low Carbon Arc Cast (LCAC), TZM, and Oxide Dispersion Strengthened (ODS) molybdenum in the post-irradiated and post-irradiated + annealed condition to determine the recovery kinetics. Irradiations performed in the High Flux Isotope Reactor (HFIR) at nominally 300 °C and 600 °C to neutron fluence levels that range from 10.5 to 246 × 1024 n/m2 (E > 0.1 MeV) resulted in relatively large increases in hardness (77-109%), while small increases in hardness (<18%) were observed for irradiations at 870-1100 °C. The hardness recovery for ODS and LCAC irradiated at 300 °C and 600 °C were shown to be complete at 980 °C and ≈ 1100-1250 °C, respectively. Isothermal annealing at 700 °C was used to determine the activation energy for recovery of LCAC and ODS (3.70-4.88 eV ± 0.28-0.77 eV), which is comparable to values reported in the literature for molybdenum vacancy self-diffusion. This suggests that recovery of LCAC and ODS is controlled by the solid-state diffusion of vacancies in the bulk, and that the finer grain size and particle size ODS does not affect this mechanism. TZM exhibited slower recovery kinetics, which can be explained by the solute atoms (titanium and zirconium) inhibiting vacancy diffusion.",

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AB - Hardness measurements were performed on wrought Low Carbon Arc Cast (LCAC), TZM, and Oxide Dispersion Strengthened (ODS) molybdenum in the post-irradiated and post-irradiated + annealed condition to determine the recovery kinetics. Irradiations performed in the High Flux Isotope Reactor (HFIR) at nominally 300 °C and 600 °C to neutron fluence levels that range from 10.5 to 246 × 1024 n/m2 (E > 0.1 MeV) resulted in relatively large increases in hardness (77-109%), while small increases in hardness (<18%) were observed for irradiations at 870-1100 °C. The hardness recovery for ODS and LCAC irradiated at 300 °C and 600 °C were shown to be complete at 980 °C and ≈ 1100-1250 °C, respectively. Isothermal annealing at 700 °C was used to determine the activation energy for recovery of LCAC and ODS (3.70-4.88 eV ± 0.28-0.77 eV), which is comparable to values reported in the literature for molybdenum vacancy self-diffusion. This suggests that recovery of LCAC and ODS is controlled by the solid-state diffusion of vacancies in the bulk, and that the finer grain size and particle size ODS does not affect this mechanism. TZM exhibited slower recovery kinetics, which can be explained by the solute atoms (titanium and zirconium) inhibiting vacancy diffusion.

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

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