An Apparatus for Performing Microtensile Tests at Elevated Temperatures inside a Scanning Electron Microscope

In this paper, we introduce an apparatus to perform microtensile tests at elevated temperatures inside a scanning electron microscope. The apparatus has a stroke of 250 μm with a displacement resolution of 10 nm and a load resolution of 9.7 μN. Measurements at elevated temperatures are performed through use of two silicon-based micromachined heaters that support the sample. Each heater consists of a tungsten heating element that also serves as a temperature gauge. To demonstrate the testing capabilities, tensile tests were performed on submicron Cu films at various temperatures up to 430 °C. Stress–strain curves show a significant decrease in yield strength and initial slope for the samples tested at elevated temperature, which we attribute to diffusion-facilitated grain boundary sliding and dislocation climb.Engineering and Applied Science

Size effects in LiF micron-scale single crystals of low dislocation density

This study examines the deformation response of 20, 5, and 1μm diameter samples fabricated by FIB-milling from bulk ultrapure LiF single crystals. The bulk crystals have a very low initial dislocation density as revealed by an etch-pit technique. Two types of 〈001〉 microsamples were compressed preferentially by single slip inside a nanoindentation system. Similar to previously studied FCC-derivative metals, LiF microsamples demonstrate dramatic strengthening achieving the engineering flow stress o ≈ 650 MPa in 1-μm samples. The stress-diameter dependence obeys a power law, σ∼D -m, where m ≈ 0.8. Stochastic variation of flow stress, fast intermittent deformation events ( avalanches ) and highly localized slip bands after avalanches - all characteristic of size effects in metals, are also observed in LiF. Possible dislocation mechanisms of the observed size effects are discussed. © 2007 Materials Research Society

The 2nd International Congress on 3DMS : 3D Materials Science 2014, L’Impérial Palace, Annecy, France, June 29-July 2 : Congress proceedings

ISBN de l'édition originale : ISBN 978-1-118-94545-2International audienceThis is a collection of manuscripts presented at the 2nd International Congress on 3D MaterialsScience, a conference organized by The Minerals, Metals & Materials Society (TMS), the AdvancedCharacterization, Testing and Simulation Committee, and the six congress organizers, and held inAnnecy, France, on June 29–July 2, 2014.Building on the great success of the first event in 2012, the 2nd Congress on 3D Materials Scienceconvened researchers and engineers to assess the state-of-the-art in 3D materials science anddetermine paths to further the global advancement of this field. More than 150 presenters andattendees from all over the world contributed to this congress in the form of presentations, livelydiscussions, and manuscripts presented in this volume. The international advisory committeemembers, representing 11 different countries, actively participated in selecting the contributions,reviewing the manuscripts, and promoting the congress.The congress consisted of 2 keynote presentations from international experts, 96 contributedpresentations (in two parallel sessions), 75 poster presentations, and 1 panel discussion. From theposter sessions, outstanding posters were selected for awards, which were presented to the authorsat the congress dinner. The event concluded with a closing panel of experts focusing the discussionon the evolution of 3D materials science in the period between the two congresses and the futuredirections.The 20 papers presented in this proceedings publication are divided into 6 sections: (1) Acquisitionand Handling of 3D Data; (2) Microstructure/Property Relationship in 3D: Characterization andSimulation; (3) Microstructure/Property Relationship in 3D: Deformation and Damage; (4) NewExperimental Techniques; (5) Analysis at the Nanoscale; (6) Dynamic Processes. It is our hopethat the 2nd International Congress on 3D Materials Science and these proceedings will furtherthe implementation of three-dimensional materials science and broaden its variety of applications