Abstract

BRETHEAU, Thierry; CREPIN, Jérôme  and  BORNERT, Michel. MATERIALS MECHANICS INSIDE THE SCANNING ELECTRON MICROSCOPE ESTUDO EXPERIMENTAL EM ESCALA MESOSCOPICA DA PLASTICIDADE E DA DEFORMAÇÃO. Rev. LatinAm. Met. Mat. [online]. 2001, vol.21, n.2, pp.21-26. ISSN 0255-6952.

In order to observe the phenomena occurring during deformation, mechanical test stages working inside a scanning electron microscope (SEM) chamber have been developed; they allow performing tests step by step, without unloading, with a fixed tensile axis, and making observations in a large range of magnification. Two stages are available: o a tensile stage with a load cell in the range 0-500 daN and a micro furnace to heat the specimen up to 800 °C, o a biaxial tension/torsion out-of-phase fatigue stage with a tension compression load up to ±1000 daN and a torque up to ±50 Nm. This system is completed by an image analyzer used to quantify microstructure morphologies and by an electron backscattering diffraction device (EBSD) that allows determining the local crystalline orientation and following its evolution under deformation. A fiducial grid technique have been developed to measure some components of the local strain tensor. The microgrids are deposited on the surface sample by an electrolithographic technique; their pitch ranges from 1 to 15 µm or more; they provide a good contrast for SEM and the underlying microstructure remains visible. From a qualitative point of view, a grid gives informations on the mechanisms occuring at the local scale during deformation. Their quantitative use gives average strain values per phase and strain distribution functions. Strain maps can also be obtained throuh the use of image analysis techniques.

Keywords : Scanning electron microscope; In situ mechanical tests; Electron backscattering diffraction; Fiducial microgrids; Local strain measurements; Deformation maps; Image analysis.