Experimental and Numerical Investigation of the Deformation and Fracture Mode of Microcantilever Beams Made of Cr(Re)/Al
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MICROSCOPIC deformation mechanisms are often responsible for the macroscopic (observable) material behavior. A logical consequence of this relationship is the steadily growing interest in investigating events on the micron scale by means of micromechanical experiments. For the past decade, we have been witnessing an intensive activity in micromechanical material testing such as compression of micropillars[1,2] or bending of microcantilevers.[3,4] Micromechanical testing can be a challenging task due to several reasons including machining of miniaturized specimens, various size WITOLD WE˛GLEWSKI, KAMIL BOCHENEK, and MICHAŁ BASISTA are with the Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawin´skiego 5B, 02-106 Warsaw, Poland. Contact e-mail: [email protected] PANDI PITCHAI and GABRIELLA BOLZON are with the Department of Civil and Environmental Engineering, Politecnico di Milano, 20133 Milan, Italy. RUTH KONETSCHNIK and DANIEL KIENER are with the Department of Material Science, Chair of Materials Physics, Montanuniversita¨t Leoben, 8700 Leoben, Austria. BERNHARD SARTORY and REINHOLD EBNER are with the Materials Center Leoben Forschung GmbH, 8700 Leoben, Austria. Manuscript submitted September 24, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS A
effects, or precise and repeatable load application. The effect of specimen size on the mechanical strength for specimen sizes ranging from micrometers to millimeters or even centimeters was studied in References 5 and 6. The results indicate that the measured strength increases with decreasing effectively loaded volume, which is mainly related to the probability of finding defects in the loaded volume of the low-ductility hard metals.[6] Accordingly, sample size-related influences can potentially affect the observed fracture properties, too.[7] Micromechanical bending experiments on microcantilevers manufactured by Focused Ion Beam (FIB) milling were used in the past to measure the elastic constants,[8,9] the fracture toughness[10–12] and the flow stress[13] of single crystals. More recently, they were used for determining the flexural strength of individual ceramic particles extracted from a metal matrix,[14] or partially embedded in a metal matrix.[15] These tests proved effective in providing microscale values of the mechanical properties that are particularly needed in numerical simulations of the material behavior. Metal–matrix composites (MMCs) with ceramic reinforcements are advanced structural materials used in many sectors including aerospace, automotive, railway, electronics and power industries because of their superior performance in demanding in-service conditions
such as high temperature, high pressure, chemically aggressive environment, complex mechanical loading and combinations thereof. MMCs manifest high stiffness and high-specific strength, enhanced wear resistance and superior thermal properties.[16] The properties of MMCs can be designed for specific applications via a number of factors including the volume fractions, type, shap
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