High-entropy alloys (HEAs) are a novel class of alloys that have many desirable properties. The serrated flow that occurs in high-entropy alloys during mechanical deformation is an important phenomenon since it can lead to significant changes in the microstructure of the alloy. In this article, we review the recent findings on the serration behavior in a variety of high-entropy alloys. Relationships among the serrated flow behavior, composition, microstructure, and testing condition are explored. Importantly, the mechanical-testing type (compression/tension), testing temperature, applied strain rate, and serration type for certain high-entropy alloys are summarized. The literature reveals that the serrated flow can be affected by experimental conditions such as the strain rate and test temperature. Furthermore, this type of phenomenon has been successfully modeled and analyzed, using several different types of analytical methods, including the mean-field theory formalism and the complexity-analysis technique. Importantly, the results of the analyses show that the serrated flow in HEAs consists of complex dynamical behavior. It is anticipated that this review will provide some useful and clarifying information regarding the serrated-flow mechanisms in this material system. Finally, suggestions for future research directions in this field are proposed, such as the effects of irradiation, additives (such as C and Al), the presence of nanoparticles, and twinning on the serrated flow behavior in HEAs.

The recent development of multicomponent, high-entropy oxides (HEOs) has sparked research into ceramics with significant compositional and structural diversity. The wide range of compositions and structures achievable with these HEOs presents a promising research opportunity, as these materials may be custom-designed to serve in several important applications, from chemical catalysis to lithium-ion batteries. Many of the unique properties which make these materials viable for a variety of applications are attributed to the characteristic single-phase (SP) structure of HEOs. As such, some researchers of HEOs have focused on understanding the driving force which results in this transition from a multiphase to a SP structure. The continued development of these materials relies on establishing a sound fundamental understanding of these critical phase transformations. To that end, in this review, we will go over the recent research advancements investigating phase transitions in HEOs. In this review, we will leverage mathematical and empirical evidence to compare the effects of enthalpic and entropic contributions to the free energy of mixing and, in turn, their impact on the transition to SP, HEOs. Emphasis will be placed on the role of entropy stabilization in these phase transitions as well as other property effects arising from high-entropic lattice disorder.

Ferroelectrics are of practical interest for non‐volatile data storage due to their reorientable, crystallographically defined polarization. Yet efforts to integrate conventional ferroelectrics into ultrathin memories have been frustrated by film‐thickness limitations, which impede polarization reversal under low applied voltage. Wurtzite materials, including magnesium‐substituted zinc oxide (Zn,Mg)O, have been shown to exhibit scalable ferroelectricity as thin films. In this work, the origins of ferroelectricity in (Zn,Mg)O are explained, showing that large strain fluctuations emerge locally in (Zn,Mg)O and can reduce local barriers to ferroelectric switching by more than 40%. Concurrent experimental and computational evidence of these effects are provided by demonstrating polarization switching in ZnO/(Zn,Mg)O/ZnO heterostructures featuring built‐in interfacial strain gradients. These results open up an avenue to develop scalable ferroelectrics by controlling strain fluctuations atomistically.