Revealing hidden defects through stored energy measurements of radiation damage

TL;DR

This paper demonstrates that measuring excess energy through differential scanning calorimetry can detect and quantify irradiation-induced defects in materials more effectively than traditional microscopy, revealing hidden defects and new recovery mechanisms.

Contribution

It introduces a novel approach combining calorimetry and molecular dynamics simulations to uncover defects invisible to conventional techniques.

Findings

DSC detects defect densities 5 times higher than TEM

Two distinct energetic processes identified during annealing

Simulations reveal new defect recovery mechanisms

Abstract

With full knowledge of a material's atomistic structure, it is possible to predict any macroscopic property of interest. In practice, this is hindered by limitations of the chosen characterisation techniques. For example, electron microscopy is unable to detect the smallest and most numerous defects in irradiated materials. Instead of spatial characterisation, we propose to detect and quantify defects through their excess energy. Differential scanning calorimetry (DSC) of irradiated Ti measures defect densities 5 times greater than those determined using transmission electron microscopy (TEM). Our experiments also reveal two energetically-distinct processes where the established annealing model predicts one. Molecular dynamics (MD) simulations discover the defects responsible and inform a new mechanism for the recovery of irradiation-induced defects. The combination of annealing experiments and simulations can reveal defects hidden to other characterisation techniques, and has the potential to uncover new mechanisms behind the evolution of defects in materials.