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Stable Speckle Patterns for Nano-scale Strain Mapping up to 700 °C

Published version
Peer-reviewed

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Authors

Edwards, TEJ 
Di Gioacchino, Fabio  ORCID logo  https://orcid.org/0000-0003-2056-1510
Springbett, HP 
Oliver, RA 
Clegg, WJ 

Abstract

The digital image correlation (DIC) of speckle patterns obtained by vapour-assisted gold remodelling at 200 – 350 °C has already been used to map plastic strains with submicron resolution. However, it has not so far proved possible to use such patterns for testing at high temperatures. Here we demonstrate how a gold speckle pattern can be made that is stable at 700 °C, to study deformation in a commercial TiAl alloy (Ti-45Al-2Nb- 2Mn(at%)-0.8 vol% TiB2). The pattern is made up of a uniformly sized random array of Au islands as small as 15 nm in diameter, depending on reconstruction parameters, with a sufficiently small spacing to be suitable for nano-scale, nDIC, strain mapping at a subset size of 60 × 60 nm2 . It can be used at temperatures up to 700 °C for many hours, for high cycle fatigue testing for instance. There is good particle attachment to the substrate. It can withstand ultra-sound cleaning, is thermally stable and has a high atomic number contrast for topography-free backscatter electron imaging.

Description

Keywords

digital image correlation, gold remodelling, titanium aluminide, sub-micron DIC, nano-DIC

Journal Title

Experimental Mechanics

Conference Name

Journal ISSN

0014-4851
1741-2765

Volume Title

Publisher

Springer
Sponsorship
Engineering and Physical Sciences Research Council (EP/M005607/1)
EPSRC / Rolls-Royce Strategic Partnership (EP/M005607/1)