Heterogeneous materials: a new class of materials with unprecedented mechanical properties

TLDR

Heterogeneous materials, composed of domains with dramatic strength differences and sizes ranging from micrometers to millimeters, offer superior strength–ductility combinations beyond homogeneous materials. The authors present a perspective on heterogeneous materials as a new class that achieves these superior mechanical properties. Large strain gradients at domain interfaces generate significant back‑stress, and high interface density maximizes this back‑stress, constituting a new strengthening mechanism. The authors find that this back‑stress mechanism yields high back‑stress work hardening, improving ductility and overall mechanical performance.

Abstract

Here we present a perspective on heterogeneous materials, a new class of materials possessing superior combinations of strength and ductility that are not accessible to their homogeneous counterparts. Heterogeneous materials consist of domains with dramatic strength differences. The domain sizes may vary in the range of micrometers to millimeters. Large strain gradients near domain interfaces are produced during deformation, which produces a significant back-stress to strengthen the material and to produce high back-stress work hardening for good ductility. High interface density is required to maximize the back-stress, which is a new strengthening mechanism for improving mechanical properties.