High-entropy herringbone alloy: Eutectic high-entropy alloys have a dual phase structure that could be useful for optimizing a material’s properties. Shi et al . found that directional solidification of an aluminum-iron-cobalt-nickel eutectic high-entropy alloy created a herringbone-patterned microstructure that was extremely resistant to fracture (see the Perspective by An). The structure contained lamellae of hard and soft phases, and the cracks that formed in the hard phase were arrested at the boundary of the soft phase. This, along with stress transfer, allowed a tripling of the maximal elongation while retaining high strength. —BG

Residual stress exists extensively in biological and engineering structures. Here we report that residual stress can be engineered to significantly enhance the strength and ductility of gradient materials. In-situ synchrotron experiments revealed that the strongest strain hardening occurred in the layer with the highest compressive residual stress in a gradient structure. This layer remained elastic longer than adjacent layers during tension, producing high hetero-deformation induced stress to increase strength and enhancing work hardening even after the disappearance of the compressive stress to increase ductility. This finding provides a new paradigm for designing gradient structures for superior mechanical properties. Impact Statement We show that compressive residual stress layer in SMAT-processed gradient material produces hetero-deformation induced hardening, which played a major role in improving strength and ductility. GRAPHICAL ABSTRACT

The high entropy alloy concept offers unique opportunities for the design of advanced materials with unprecedented properties. However, hitherto most of the research efforts are focused on structural materials. Here, by employing the core effect of severe lattice distortion in high entropy alloys, a novel functional NiCuTiHf_0.6Zr_0.4 high entropy alloy exhibiting intriguing wide-temperature-range perfect superelasticity in a broad temperature range from 263 to 463 K and giant elastocaloric effect with the maximum adiabatic temperature change of 9.3 K is developed. This work opens the door for designing high-performance superelastic and elastocaloric functional materials with the high entropy alloy concept. GRAPHICAL ABSTRACT IMPACT STATEMENT A novel functional high entropy alloy with intriguing wide-temperature-range perfect superelasticity and giant elastocaloric effect is sucessfully developed by employing the severe lattice distortion which leads to high yield strength.

Multiferroic phase-transforming alloys demonstrate intriguing multicaloric effects, but they are intrinsically brittle and their elastocaloric effect shows poor cyclability, which remains a major challenge for exploiting more efficient multicaloric refrigeration. Here, by employing a novel strategy of strengthening grain boundary, the cyclability of elastocaloric effect in the prototype Ni-Mn-based multiferroic phase-transforming alloys is strikingly enhanced by two orders of magnitude. Ultrahigh cyclability of a large elastocaloric effect is achieved. This not only paves the way for exploiting multicaloric effects for more efficient cooling, but also provides a strategy for overcoming the cyclability issues in the ubiquitous brittle intermetallic phase-transforming materials. GRAPHICAL ABSTRACT IMPACT STATEMENT The cyclability of elastocaloric effect in the prototype Ni-Mn-based multiferroic phase-transforming alloys has been strikingly enhanced by two orders of magnitude through employing the strategy of strengthening grain boundary.