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Title: Cavity morphology in a Ni based superalloy under heavy ion irradiation with cold pre-injected helium. I

In order to understand radiation damage in the nickel based superalloy Inconel X-750 in thermal reactors, where (n, α) transmutation reaction also occurred in addition to fast neutron induced atomic displacement, heavy ion (1 MeV Kr{sup 2+}) irradiation with pre-injected helium was performed under in-situ observations of an intermediate voltage electron microscope at Argonne National Laboratory. By comparing to our previous studies using 1 MeV Kr{sup 2+} irradiation solely, the pre-injected helium was found to be essential in cavity nucleation. Cavities started to be visible after Kr{sup 2+} irradiation to 2.7 dpa at ≥200 °C in samples containing 200 appm, 1000 appm, and 5000 appm helium, respectively, but not at lower temperatures. The cavity growth was observed during the continuous irradiation. Cavity formation appeared along with a reduced number density of stacking fault tetrahedra, vacancy type defects. With higher pre-injected helium amount, a higher density of smaller cavities was observed. This is considered to be the result of local trapping effect of helium which disperses vacancies. The average cavity size increases with increasing irradiation temperatures; the density reduced; and the distribution of cavities became heterogeneous at elevated temperatures. In contrast to previous characterization of in-reactor neutron irradiated Inconel X-750, no obvious cavity sinkmore » to grain boundaries and phase boundaries was found even at high doses and elevated temperatures. MC-type carbides were observed as strong sources for agglomeration of cavities due to their enhanced trapping strength of helium and vacancies.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Mechanical and Materials Engineering, Queen's University Kingston, Ontario K7L 3N6 (Canada)
  2. Material Science Division, Argonne National Laboratory Argonne, Illinois 60439 (United States)
Publication Date:
OSTI Identifier:
22277895
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; ATOMIC DISPLACEMENTS; COMPARATIVE EVALUATIONS; DENSITY; ELECTRIC POTENTIAL; FAST NEUTRONS; GRAIN BOUNDARIES; HELIUM; INCONEL ALLOYS; KRYPTON IONS; MORPHOLOGY; NICKEL; NICKEL BASE ALLOYS; RADIATION DOSES; STACKING FAULTS; TRAPPING; VACANCIES