This paper presents a perspective on heterogeneous materials, a new class of materials that exhibit superior combinations of strength and ductility. Heterogeneous materials consist of domains with significant strength differences, typically ranging from micrometers to millimeters in size. During deformation, large strain gradients near domain interfaces produce significant back-stress, which strengthens the material and enhances ductility through high back-stress work hardening. The high interface density is crucial for maximizing back-stress, a novel strengthening mechanism.
The authors discuss the deformation behavior of heterogeneous materials, which can be divided into three stages: elastic deformation, strain gradient development, and plastic deformation. In the second stage, the strain gradient near the domain interface leads to geometrically necessary dislocation pile-ups, creating a synergetic strengthening effect. In the third stage, strain partitioning occurs, where soft domains sustain higher strains than hard domains, further enhancing ductility.
Back-stress, a key factor in the mechanical properties of heterogeneous materials, is explained as a long-range stress created by geometrically necessary dislocations. It is connected to plastic strain gradients and can be maximized by designing heterogeneous structures with high interface density and strain partitioning. The heterogeneous lamella structure is highlighted as a near-ideal structure, showing dramatic improvements in strength and ductility.
The paper concludes by noting the emerging nature of heterogeneous materials as a research field, with potential for practical applications and a growing community of researchers.This paper presents a perspective on heterogeneous materials, a new class of materials that exhibit superior combinations of strength and ductility. Heterogeneous materials consist of domains with significant strength differences, typically ranging from micrometers to millimeters in size. During deformation, large strain gradients near domain interfaces produce significant back-stress, which strengthens the material and enhances ductility through high back-stress work hardening. The high interface density is crucial for maximizing back-stress, a novel strengthening mechanism.
The authors discuss the deformation behavior of heterogeneous materials, which can be divided into three stages: elastic deformation, strain gradient development, and plastic deformation. In the second stage, the strain gradient near the domain interface leads to geometrically necessary dislocation pile-ups, creating a synergetic strengthening effect. In the third stage, strain partitioning occurs, where soft domains sustain higher strains than hard domains, further enhancing ductility.
Back-stress, a key factor in the mechanical properties of heterogeneous materials, is explained as a long-range stress created by geometrically necessary dislocations. It is connected to plastic strain gradients and can be maximized by designing heterogeneous structures with high interface density and strain partitioning. The heterogeneous lamella structure is highlighted as a near-ideal structure, showing dramatic improvements in strength and ductility.
The paper concludes by noting the emerging nature of heterogeneous materials as a research field, with potential for practical applications and a growing community of researchers.