Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling

TL;DR

This study combines experimental measurements and multiscale modeling to analyze how helium implantation causes lattice swelling and elastic modulus changes in tungsten alloys, revealing defect-driven microstructural effects.

Contribution

It introduces an integrated approach using X-ray micro-diffraction, surface acoustic wave spectroscopy, and multiscale modeling to understand helium-induced damage in tungsten alloys.

Findings

Lattice swelling is consistent with defect relaxation volumes.

Surface acoustic wave velocity decreases significantly due to helium implantation.

Model predictions align well with experimental measurements.

Abstract

Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure lattice swelling and elastic modulus changes in a W-1%Re alloy after implantation with 3110 appm of helium. A fraction of a percent observed lattice expansion gives rise to an order of magnitude larger reduction in the surface acoustic wave velocity. A multiscale elasticity, molecular dynamics, and density functional theory model is applied to the interpretation of observations. The measured lattice swelling is consistent with the relaxation volume of self-interstitial and helium-filled vacancy defects that dominate the helium-implanted material microstructure. Molecular dynamics simulations confirm the elasticity model for swelling. Elastic properties of the implanted surface layer also change due to defects. The reduction of surface acoustic wave velocity predicted by density functional theory calculations agrees remarkably well with experimental observations.