Microstructural stability and mechanical behavior of FeNiMnCr high entropy alloy under ion irradiation

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.

Single-Phase Concentrated Solid-Solution Alloys: Bridging Intrinsic Transport Properties and Irradiation Resistance

“…However, the temperature dependence in the FeNiMnCr 0.66 is less significant compared with the conventional Fe-Cr-Ni alloys. Moreover, considerably higher loop density and lower loop size have been reported in FeNiMnCr 0.66 , compared with those in the conventional Fe-Ni-Cr alloys (Kumar et al, 2016). Furthermore, higher fraction of faulted loops have been observed in the more compositionally complex alloys, indicating that increasing compositional complexity can extend the incubation period and delay loop growth .…”

“…Unlike in Lu et al (2016b), no voids have been observed in both cases at all the test temperatures. For the observable defect clusters, the density decreases but the size increases with increasing irradiation temperature (Kumar et al, 2016;Yang et al, 2018). However, the temperature dependence in the FeNiMnCr 0.66 is less significant compared with the conventional Fe-Cr-Ni alloys.…”

“…The temperature dependence of microstructure evolution under ion irradiations at elevated temperatures has been performed in FeNiMnCr 0.66 to 10 dpa at 400-700 • C (Kumar et al, 2016), and in NiCoFeCrAl 0.1 to 31 dpa at 250-650 • C FIGURE 6 | (a) Ion channeling spectra of several Ni-containing FCC SP-CSAs irradiated with 1.5 MeV Ni ions to the fluence of 1 × 10 14 cm −2 , adapted from Zhang et al (2016). Reproduced with the permission of the copyright holder (Cambridge University Press).…”

“…Note that irradiation temperature is a critical parameter for high temperature irradiation induced effects, e.g., swelling, and the temperature dependence varies with alloy compositions. The experimental studies till present primarily have focused either on one HEA at different irradiation temperatures (Kumar et al, 2016;Yang et al, 2018) or on the effects of compositional complexity at single irradiation temperature (Jin et al, 2016c;Lu et al, 2016b). How the number and species of principal alloying elements affect the temperature dependence of irradiation response in SP-CSAs requires future systematic studies.…”

Nanostructured multielement (TiHfZrNbVTa)N coatings before and after implantation of N+ ions (1018cm−2): Their structure and mechanical properties

“…[1,2]. It is widely used for semiconductor doping in micro-and nanoelectronics, medicine [3,4], space, chemical and aviation industries [5][6][7][8][9]. The main advantages of ion implantation are preservation of sample sizes, locality (small projective path), high reproducibility, absence of problems with adhesion etc.…”