Temperature dependent dispersoid stability in ion-irradiated ferritic-martensitic dual-phase oxide-dispersion-strengthened alloy: Coherent interfaces vs. incoherent interfaces

Abstract

a b s t r a c tIn this study, the microstructure of a 12Cr ferritic-martensitic oxide-dispersion-strengthened (ODS) alloy is studied before and after Fe ion irradiation up to 200 peak displacements per atom (dpa). Irradiation temperature ranges from 325 to 625 C. Before irradiation, both coherent and incoherent dispersoids exist in the matrix. In response to irradiation, the mean sizes of dispersoids in both the ferrite and tempered martensite phases change to equilibrium values that increase with irradiation temperature. The evolution of dispersoids under irradiation is explained by a competition between athermalradiation-driven shrinkage and thermal-diffusion-driven growth, with interface coherency affecting the growth mechanism. However, each coherency type exhibits different evolution behavior under irradiation. Coherent dispersoids, regardless of their initial size, change toward an equilibrium size at each temperature tested. On the other hand, incoherent dispersoids are destroyed at lower test temperatures but survive while shrinking in size at higher temperatures. This difference in behavior can be explained by the lower interfacial energy of coherent dispersoids in comparison with incoherent dispersoids. This study sheds light on the roles of interface configurations in maintaining dispersoid integrity under irradiation.

Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation

“…This explains the changes of the density and size of oxides before and after irradiation in coarse grains of COS-2. The evolution of oxide particles in COS-2 is similar to a previous work conducted by Chen27. Chen and his colleagues systematically studied the coherency of the dispersoids before and after irradiation.…”

The Mechanism of Radiation-Induced Nanocluster Evolution in Oxide Dispersion Strengthened and Ferritic-Martensitic Alloys

“…Finally, it is observed that upon both Fe 2+ and proton irradiation, the average sizes of the oxide nanoclusters appear to asymptotically approach steady-states at doses >3 dpa, consistent with previous modeling [57,74,79] and experimental [5,79,84,107,206] efforts.…”

“…Using high resolution transmission electron microscopy (HRTEM), several studies have found oxides to generally be coherent with the matrix [69,79,88,96,128]. Observations in literature also suggest that coherency may be closely related to the size of clusters, with smaller oxides trending towards non-stoichiometric chemistry with Y:Ti ratio ~0.50 [9,13], while larger oxides trend towards a Y:Ti ~1.3 [9,13] with a pyrochlore Y2Ti2O7 or orthorhombic Y2TiO5 structure [124,[130][131][132][133][134].…”

“…Another model similar to the NHM model (developed by Wagner [80]) is advanced by Chen, et al [79] to predict nanocluster cluster evolution in ODS alloys (Section 2.4.6). The governing equation for this model is:…”

A review of the irradiation evolution of dispersed oxide nanoparticles in the b.c.c. Fe-Cr system: Current understanding and future directions

“…Size changes are the most widely reported factor describing the irradiation evolution of NPs, and it is of interest to understand these size changes as a function of irradiation dose. Only a few studies have carried out NP size measurements over a range of doses (with all other irradiation parameters fixed); these results are represented in Chen, et al [8] both observe decreasing NP size with increasing dose, with a steady-state reached between 50 and 150 dpa. But the similarities end there.…”