Electron-irradiation-facilitated production of chemically homogenized nanotwins in nanolaminated carbides

TL;DR

This study demonstrates a novel method using electron irradiation to produce chemically homogenized nanotwins in carbide ceramics, significantly enhancing their hardness through atomic-scale defect engineering.

Contribution

The paper introduces a new electron irradiation technique to create ultrathin nanotwin platelets in carbides by controlling antisite defects and chemical homogeneity.

Findings

Nanotwin platelets can be produced in carbides via electron irradiation.

Chemical homogenization enhances the hardness of the material.

The process allows tuning of twin width and chemical composition.

Abstract

Twin boundaries have been exploited to stabilize ultrafine grains and improve the mechanical properties of nanomaterials. The production of twin boundaries and nanotwins is however prohibitively challenging in carbide ceramics. Using scanning transmission electron microscopes as a unique platform for atomic-scale structure engineering, we demonstrate that twin platelets could be produced in carbides by engineering antisite defects. Antisite defects at metal sites in various layered ternary carbides are collectively and controllably generated and the metal elements are homogenized by electron irradiation, which transforms the twin-like lamellae into nanotwin platelets. Accompanying the chemical homogenization, {\alpha}-Ti3AlC2 transforms to unconventional \b{eta}-Ti3AlC2. The chemical homogeneity and the width of the twin platelets can be tuned by the dose and energy of bombarding electrons. Chemically homogenized nanotwins can boost the hardness by ~45%. Our results provide a new way to produce ultrathin (<5 nm) nanotwin platelets in scientifically and technologically important carbide materials and showcase the feasibility of defect engineering by an angstrom-sized electron probe.