ESTUDO IN SITU DA DEFORMAÇÃO CRIOGÊNICA DE METAIS CFC DE DIFERENTES ENERGIAS DE DEFEITO DE EMPILHAMENTO

Abstract

Three FCC commercially pure metals (aluminum, copper and silver) were deformed by uniaxial tensile tests and were characterized by in situ X-ray diffraction, using a synchrotron source, at room (293K) and cryogenic (77K) temperatures. The partial suppression of dynamic recovery due to cryogenic processing allows an improvement in mechanical properties, such as ductility and strength. This suppression results in an increase in the internal defects density of metals during the strain, promoting microstructural refining and increase of microstrain. The microstructural refinement is manifested by dimples evolution on the fracture surface and reduction of average crystallite size. All metals present higher mechanical strength at cryogenic temperature, nevertheless the ductility only was increased in copper and silver. This behavior is attributed to lower stacking fault energy of these metals in comparison with aluminum.