Outstanding radiation resistance of tungsten-based high-entropy alloys

Abstract

A body-centered cubic W-based refractory high entropy alloy with outstanding radiation resistance has been developed. The alloy was grown as thin films showing a bimodal grain size distribution in the nanocrystalline and ultrafine regimes and a unique 4-nm lamella-like structure revealed by atom probe tomography (APT). Transmission electron microscopy (TEM) and x-ray diffraction show certain black spots appearing after thermal annealing at elevated temperatures. TEM and APT analysis correlated the black spots with second-phase particles rich in Cr and V. No sign of irradiation-created dislocation loops, even after 8 dpa, was observed. Furthermore, nanomechanical testing shows a large hardness of 14 GPa in the as-deposited samples, with near negligible irradiation hardening. Theoretical modeling combining ab initio and Monte Carlo techniques predicts the formation of Cr- and V-rich second-phase particles and points at equal mobilities of point defects as the origin of the exceptional radiation tolerance.

Superconductivity in a uranium containing high entropy alloy

“…Earlier work revealed that the Zr-based analogues and other HEAs exhibit high strength, ductility, and damage resistant properties across a broad range of temperatures, and the work presented here demonstrates that this extends to the actinide family. This suggests that this and other HEAs may provide a next generation waste form for radioactive isotopes, similar to other HEA systems [11][12][13][14] . We also anticipate that the [TaNb] 1-x (TiAHf) x HEA series will accommodate other radioactive elements (A = actinide) in the place of A = U.…”

“…Synthesis. Specimens were produced using the arc furnace technique, as earlier described for the Zr-based analogues 5,13,14 . The starting materials were metallic niobium (purity 99.9%), tantalum (purity 99.9%), uranium (purity 99.9%), hafnium (purity 99.9%), and titanium (purity 99.99%).…”

“…This occurs when the mixing entropy overrides simple stoichiometric/crystalline phase selection, and leads to a large chemical compositional space that is distinct from that of traditional alloys where a few molar percent of one element is added to another (e.g., as for sterling silver, modern steels, and Be-Cu). Many attractive behaviors are observed in HEAs, including fracture resilience at cryogenic temperatures 6,7 , excellent mechanical properties at elevated temperatures 8 , high strength 9,10 , and high resistance to radiation damage [11][12][13][14] . An emerging class of HEAs are those hosting 4d and 5d transition metals that exhibit phonon mediated superconductivity with large upper critical fields 5,15,16 .…”

High-entropy alumino-silicides: a novel class of high-entropy ceramics

“…Generally, in a HEA, four or more principal elements can be mixed in near-equiatomic ratios or at least with each element being between 5 at% and 35 at% to generate a maximum molar configurational entropy of ΔS mix =R•lnN, where N is the number of components and R is the gas constant [1][2][3]. As a result, HEAs exhibit superior strength and ductility [4], outstanding irradiation resistance [5], good corrosion resistance [6], high fracture toughness [7], interesting creep characteristics [8] and plastic behavior [9]. Inspired by HEAs concept, the concept of high-entropy ceramics (HECs), namely multicomponent ionic compounds, was first proposed in the multicomponent metal oxides in 2015 [10] and then it has been gaining significant interest in recent years.…”

Strain-rate sensitivity of high-entropy alloys and its significance in deformation

“…One important advantage of the thermally-activated deformation analysis is that thermal barriers which control the dislocation motion and deformation kinetics can be reasonably determined out of various obstacles observed by nanostructural analysis tools. Over the past decade, high-entropy alloys (HEAs) have been investigated in a wide range of research fields such as irradiation resistance [2], corrosion resistance [3], and mechanical properties [4,5]. In particular, temperature and strain-rate dependence on the plastic flow [1,6] of HEAs has attracted attention from materials science society.…”