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Autumn 2008 Seminar Series
Monday, November 24, at 3:30 p.m.
Room 264 MacQuigg Labs
Paul Shade
PhD Candidate advised by Dr. Hamish Fraser
Materials Science and Engineering
The Ohio State University
Small Scale Mechanical Testing Techniques and Application to Evaluate a Single Crystal Nickel Superalloy
Abstract
Small scale mechanical testing affords the possibility of measuring constitutive materials properties and studying intrinsic size effects on mechanical behavior. Accordingly, Uchic and colleagues developed a microcompression testing technique about five years ago. Published studies employing this technique have clearly demonstrated that size-scale effects exist independently of other previously known size effects such as nucleation-controlled deformation (whiskers) or the presence of imposed strain gradients (nanoindentation). The overwhelming majority of these studies have focused on simple metals. In this study, the microcompression test methodology is employed to evaluate Rene N5, an engineering alloy with a varying structure at different length scales. Compression samples are tested in a single-slip orientation using sample diameters in a range from a couple to tens of micrometers, while selectively testing samples from dendrite core and inter-dendritic regions.
Additionally, a custom in-situ SEM testing device for performing uniaxial mechanical tests on micrometer-scale samples is employed. This device allows one to access both tensile and compressive test modes, and also directly observe the spatial distribution of deformation events through continuous recording of SEM images. The present study will highlight the effect that the device construction--in particular, the lateral stiffness of the compression platen or tensile grip--has on the resultant mechanical response of microcrystals that are oriented for single-slip deformation.
Bio
Paul joined the Ohio State University in autumn 2000. He received a BS in Materials Science and Engineering in spring 2005 and has pursued a PhD in Materials Science and Engineering under the guidance of his advisor, Hamish Fraser. Additionally, Paul has worked in the Microstructural Characterization Facility at WPAFB.
