Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

Abstract

A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications.

Quantum critical behavior in the asymptotic limit of high disorder in the medium entropy alloy NiCoCr0.8

“…19 For increasing Cr concentrations, x, there is a rapid nearly exponential decrease in T c , and in addition to the rapid depression of T c , increasing the Cr concentration introduces a type of frustration since the spins on the Cr atoms want to be antiparallel to neighboring Ni, Co, and Cr spins, which cannot be satisfied on a fcc lattice. For Cr concentrations greater than x ≈ 0.4, theory (KKR-CPA) 14,19,20 greatly over-estimates both the spontaneous magnetic moments and T c (see Fig. 3c.…”

“…14 The alloys are also unusual because all elements have roughly equal concentrations and the dilute impurity approximation is invalid. A recent theoretical model based on enthalpies of formation coupled with entropy stabilization successfully predicts which combination of elements will form a single-phase solid solution.…”

Local Structure and Short-Range Order in a NiCoCr Solid Solution Alloy

“…Previously theoretical calculations [11,35] did suggest that phonons are more dispersive in the systems with the increase of chemical complexity. Rietveld refinement of the neutron PDF of NiCoCr yields the Debye-Waller factor of 0.0085(2) Å 2 , which is noticeably larger than that of pure Ni at room temperature (0.0046 Å 2 [36]).…”

“…As a new class of materials, these compositionally complex alloys have attracted a large number of research interests over the past decade, leading to the discovery of some excellent mechanical properties and interesting physical properties [3][4][5][6][7][8][9][10]. Recently, many multicomponent solid solution alloys with 3d transition elements from Cr to Ni in the periodic table, which have similar atomic size, have been synthesized and all of these Ni-based alloys have a simple face-centered cubic (fcc) structure [10][11][12][13][14]. Some of these HEAs exhibit high strength and excellent wear resistance at low and high temperatures, which makes them attractive for industrial applications.…”

“…Cr also has different interesting effects to nuclear alloys, such as improved irradiation performance [11], reduced swelling [40], and reduced radiation-induced ductile-brittle transition temperature [41] by adjusting Cr concentration. All these effects in the alloys originate from the local structures, which may relate to SRO.…”