Microstructural stability and mechanical behavior of FeNiMnCr high entropy alloy under ion irradiation. (July 2016)

• Record Type: Journal Article
• Authors: Kumar, N.A.P. Kiran; Li, C.; Leonard, K.J.; Bei, H.; Zinkle, S.J.
• Is Part Of: Acta materialia. Volume 113(2016)
• Page Start: 230
• Page End: 244
• Publication Date: 2016-07
• Subjects: High entropy alloy -- Radiation-induced segregation -- Dislocation loops -- Concentrated multi-component solid solution alloy -- Irradiation defects; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2016.05.007
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: In recent years, high entropy alloys (HEAs) have attracted significant attention due to their excellent mechanical properties and good corrosion resistance, making them potential candidates for high temperature fission and fusion structural applications. However there is very little known about their radiation resistance, particularly at elevated temperatures relevant for energy applications. In the present study, a single phase (face centered cubic) concentrated solid solution alloy of composition 27%Fe-28%Ni-27%Mn-18%Cr was irradiated with 3 or 5.8 MeV Ni ions at temperatures ranging from room temperature to 700 °C and midrange doses from 0.03 to 10 displacements per atom (dpa). Transmission electron microscopy (TEM), scanning transmission electron microscopy with energy dispersive x-ray spectrometry (STEM/EDS) and X-ray diffraction (XRD) were used to characterize the radiation defects and microstructural changes. Irradiation at higher temperatures showed evidence of relatively sluggish solute diffusion with limited solute depletion or enrichment at grain boundaries. The main microstructural feature at all temperatures was high-density small dislocation loops. Voids were not observed at any irradiation condition. Nano-indentation tests on specimens irradiated at room temperature showed a rapid increase in hardness ∼35% and ∼80% higher than the unirradiated value at 0.03 and 0.3 dpa midrange doses, respectively. The irradiation-induced hardening was less pronounced for 500 °C irradiations (<20% increase after 3 dpa). Overall, the examined HEA material exhibits superior radiation resistance compared to conventional single phase Fe-Cr-Ni austenitic alloys such as stainless steels. The present study provides insight on the fundamental irradiation behavior of a single phase HEA material over a broad range of irradiation temperatures. Graphical abstract: Highlights: Detailed irradiation behavior of a high entropy alloy has been reported for a wide range of irradiation conditions. Significant suppression in radiation-induced segregation was observed compared to irradiated conventional austenitic Fe-Cr-Ni alloys. Voids were not observed up to midrange doses of 10 dpa over a wide range of irradiation temperatures.