Irradiating particle type effects on ODS nano/microstructure evolution


The irradiation evolution of oxide nanoclusters in ODS steels is not independent of the irradiating particle type.  However, particle type effects are a combination of several factors, including the irradiation dose rate, and the damage cascade size, energy, efficiency, and lifetime (generally termed the “damage cascade morphology”).  It is difficult to deconvolute these factors, especially experimentally.

We take the approach of irradiating the identical ODS heat with three different particles (protons, Fe2+ self-ions, and neutrons) to otherwise fixed conditions (3 displacements per atom (dpa) at a temperature of 500°C).  This approach is unique because it does not employ an irradiation temperature shift, which is commonly believed to be necessary to produce comparable microstructures when increasing the irradiation dose rate.  Rather, our approach enables us to isolate particle type effects without the complication of the temperature shift.  We utilize atom probe tomography (APT) for three-dimensional, high spatial resolution chemical identification and nanocluster analysis (see figure).

Irradiation-induced changes to cluster sizes, number densities, and stoichiometries are characterized.  We find that the size and disordering efficiency of a cascade are the factors that most closely correlate with nanocluster dissolution.


  • DOE Nuclear Science User Facilities projects 14-486, 14-485, 15-540, 15-569, and 16-710
  • US Nuclear Regulatory Commission award NRC-HQ-84-14-G-0056


  1. M.J. Swenson and J.P. Wharry.  The comparison of microstructure and nanocluster evolution in proton and neutron irradiated Fe–9%Cr ODS steel to 3 dpa at 500°C.  Journal of Nuclear Materials 467.1 (2015) 97-112.  doi: 10.1016/j.jnucmat.2015.09.022
  2. C.K. Dolph, D.J. da Silva, M.J. Swenson and J.P. Wharry.  Plastic zone size for nanoindentation of irradiated Fe–9%Cr ODS.  Journal of Nuclear Materials 481 (2016) 33-45.  doi: 10.1016/j.jnucmat.2016.08.033
  3. K.H. Yano, M.J. Swenson, Y. Wu, and J.P. Wharry.  TEM in situ micropillar compression tests of ion irradiated oxide dispersion strengthened alloy.  Journal of Nuclear Materials 483 (2017) 107-120.  doi: 10.1016/j.jnucmat.2016.10.049
  4. M.J. Swenson and J.P. Wharry.  A predictive model for irradiation-induced nanocluster evolution in b.c.c. Fe-based alloys.  The Minerals, Metals & Materials Society Annual Meeting, San Diego CA, March 2017.
  5. M.J. Swenson and J.P. Wharry.  Comparison of neutron, proton, and self-ion irradiation of Fe-9%Cr ODS at 3 dpa, 500°C.  The Minerals, Metals & Materials Society Annual Meeting, Nashville TN, March 2016.
  6. M.J. Swenson, C.K. Dolph, and J.P. Wharry. Correlation between the microstructure and mechanical properties of irradiated Fe-9Cr ODS. Transactions of the American Nuclear Society – 2014 Annual Meeting, 110 (2014) 421-424.​

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