Swelling and structure of vanadium alloys irradiated in the dynamic helium charging experiment

Technical Report · Thu Sep 01 04:00:00 EDT 1994

OSTI ID:47745

Chung, H M; Loomis, B A; Tsai, H; Nowicki, L; Gazda, J; Smith, D L ^[1]

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1. Argonne National Lab., IL (United States)

Combined effects of dynamically charged He and neutron damage on density change, void distribution, and microstructural evolution of V-4Cr-4Ti have been determined after irradiation to 18-31 dpa at 425-600{degrees}C in the Dynamic Helium Charging Experiment (DHCE). For specimens irradiated to {approx}18 dpa at 600{degrees}C with an estimated He/dpa ratio of 3-9 appm He/dpa (a range similar to the fusion-relevant ratio of {approx}5 appm He/dpa), only a few microvoids were observed at the interface of the grain matrix and some Ti(O,N,C) precipitates. No microvoids were observed either in the grain matrix or near grain boundaries. It seems that most of the dynamically produced He atoms are trapped in the grain matrix without significant void nucleation or growth. In this group of DHCE specimens, density changes were similar to those of non-DHCE (negligible He generation) specimens for a comparable fluence and irradiation temperature. Significant numbers of microvoids in the grain matrix and on localized grain boundaries were present only in specimens irradiated to {approx}31 dpa at 425{degrees}C in high-tritium capsules, in which an excessive amount of helium was generated (estimated He/dpa ratio of 10-35 appm). Discontinuous regions of void segregation on grain boundaries were observed, and void number-density was significantly lower than in other alloys irradiated in tritium-trick experiments. Density changes of the specimens were significantly higher than those from non-DHCE irradiations. Microstructural evolution in V-4Cr-4Ti was similar for DHCE and non-DHCE irradiations, except for void number-density and distribution. As in non-DHCE specimens, irradiation-induced precipitation of ultrafine Ti{sub 5}Si{sub 3} was observed for irradiation at 600{degrees}C but not at 425{degrees}C.

• Research Organization: Oak Ridge National Lab., TN (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 47745
• Report Number(s): DOE/ER--0313/16; ON: DE95003404
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
HELIUM EMBRITTLEMENT
IRRADIATION
PHYSICAL RADIATION EFFECTS
PROGRESS REPORT
SWELLING
THERMONUCLEAR REACTOR MATERIALS
VANADIUM BASE ALLOYS