In Situ X-Ray Diffraction Analysis of Face-Centered Cubic Metals Deformed at Room and Cryogenic Temperatures
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JMEPEG https://doi.org/10.1007/s11665-019-04226-5
In Situ X-Ray Diffraction Analysis of Face-Centered Cubic Metals Deformed at Room and Cryogenic Temperatures Marcel Tadashi Izumi, John Jairo Hoyos Quintero, Maicon Rogerio Crivoi, Milene Yumi Maeda, Ricardo Sanson Namur, Denilson Jose´ Marcolino de Aguiar, and Osvaldo Mitsuyuki Cintho (Submitted January 9, 2019; in revised form June 26, 2019) The present study concerns the cryogenic processing of metals with simultaneous analysis of x-ray diffraction in a synchrotron ring. The mechanical properties improvement related to cryogenic processing of metals is attributed to the partial suppression of dynamic recovery. Thus, commercially pure metals with different stacking fault energies (silver, copper and aluminum) were deformed by uniaxial tensile tests and characterized by in situ x-ray diffraction, at room (293 K) and cryogenic (77 K) temperatures. The cryogenic processing allows a simultaneous improvement in ductility and strength for silver and copper and an improvement in strength for aluminum. This difference in mechanical properties was investigated by means of variations in crystallite size, microstrain and also the amount and size of dimples on the fracture surface. The microstructural refinement at cryogenic temperatures shows a tendency related to the stacking fault energies. Keywords
cryogenic deformation, dynamic recovery, microstrain, stacking fault energy, synchrotron radiation
1. Introduction Recent researches showed that cryogenic processing (77 K) is effective to promote twinning and suppressing of the dynamic recovery of deformed face-centered cubic (FCC) metals, thus increasing the density of crystallographic defects. Simultaneous improvement in mechanical properties, such as strength and/or ductility, may be achieved by this processing route (Ref 1-10). It is known that the recovery depends on thermally activated processes, such as cross-slip and climb. The stacking fault energy (SFE) is a very useful parameter to predict the probability of cross-slip, dynamic recovery-related phenomena (Ref 6, 7, 11). In cubic metals, slip and twinning are concurrent deformation mechanisms, and SFE is the most important parameter to predict the predominant deformation mechanism. Slipping is the dominant mechanism in most of the normal processing conditions. Nevertheless, twinning occurs in FCC metals with
Marcel Tadashi Izumi, Maicon Rogerio Crivoi, Milene Yumi Maeda, Ricardo Sanson Namur, and Osvaldo Mitsuyuki Cintho, Department of Materials Engineering, State University of Ponta Grossa, Ponta Grossa, PR 84030-900, Brazil; John Jairo Hoyos Quintero, Department of Materials Engineering, State University of Ponta Grossa, Ponta Grossa, PR 84030-900, Brazil; and Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil; and Denilson Jose´ Marcolino de Aguiar, Academic Department of Mechanics, Federal University of Technology – Parana´, Ponta Grossa 84016-210, Brazil. C
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