title: In situ nanocompression testing of irradiated copper.
abstract: Increasing demand for energy and reduction of carbon dioxide emissions has revived interest in nuclear energy. Designing materials for radiation environments necessitates a fundamental understanding of how radiation-induced defects alter mechanical properties. Ion beams create radiation damage efficiently without material activation, but their limited penetration depth requires small-scale testing. However, strength measurements of nanoscale irradiated specimens have not been previously performed. Here we show that yield strengths approaching macroscopic values are measured from irradiated ~400 nm-diameter copper specimens. Quantitative in situ nanocompression testing in a transmission electron microscope reveals that the strength of larger samples is controlled by dislocation-irradiation defect interactions, yielding size-independent strengths. Below ~400 nm, size-dependent strength results from dislocation source limitation. This transition length-scale should be universal, but depends on material and irradiation conditions. We conclude that for irradiated copper, and presumably related materials, nanoscale in situ testing can determine bulk-like yield strengths and simultaneously identify deformation mechanisms.
authors.affiliation: Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA. daniel.kiener@unileoben.ac.at
authors.forename: D
authors.initials: D
authors.lastname: Kiener
authors.forename: P
authors.initials: P
authors.lastname: Hosemann
authors.forename: S A
authors.initials: SA
authors.lastname: Maloy
authors.forename: A M
authors.initials: AM
authors.lastname: Minor