RESEARCH ARTICLE

Generalization of the Hall-Petch and inverse Hall-Petch behaviors by tuning amorphous regions in 2D solids

¹ Department of Physics, The Hong Kong University of Science and Technology, Hong Kong 999077, China
² Function Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou 510000, China
³ Department of Mechanical & Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong 999077, China
⁴ State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi'an 710049, China
⁵ The Hong Kong University of Science and Technology Shenzhen Research Institute, Shenzhen 518057, China

^* Corresponding authors (emails: huijun@xjtu.edu.cn (Huijun Zhang); yilong@ust.hk (Yilong Han))

Received: 1 September 2022
Revised: 24 October 2022
Accepted: 5 December 2022

Abstract

The strength σ_y(D) of a polycrystal can decrease or increase with the grain diameter D, i.e., the famous Hall-Petch (HP) and inverse-Hall-Petch (IHP) behaviors, respectively. However, σ_y(D) under thick grain boundaries (GBs) (i.e., GB thickness l gt;1 particle) and σ_y(l) have rarely been explored. Here we measure them by systematically varying D and l of two-dimensional glass-crystal composites in simulations. We demonstrate that increasing l and decreasing D have similar effects on reducing dislocation motions and promoting GB deformations. Consequently, the classical HP-IHP behaviors of σ_y(D,l=1) and our generalized HP-IHP behaviors of σ_y(D, l) share similar mechanisms and can be unified as σ_y (A_GB/A_tot), where A_GB/A_tot is the fraction of the amorphous region. The results reveal a way to exceed the maximum strength of normal polycrystals. The generalized HP-IHP behaviors of σ_y(D, l) should be similar in 2D and 3D, except that the HP effect in 3D is stronger.