Estabilidade microestrutural da liga Cu-0,8Cr-0,07Zr após extrusão em canal angular em temperatura criogênica
Fecha
2021-12-20Autor
Oliveira, Pedro Henrique Fernandes
Metadatos
Mostrar el registro completo del ítemResumen
Severe Plastic Deformation (SPD) are well established routes with regard to the
intense microstructural refining of metals and alloys up to the submicrometer (<
1 μm) and/or nanometer (< 100 nm) scales. Lowering the processing temperature
is also a way to increase the severity of the imposed strain, favoring strengthening
and grain refinement. Therefore, it is expected that the combination of SPD and
temperatures on the cryogenic scale allow obtaining materials with higher
strength. However, severely deformed microstructures at cryogenic temperatures
have limited use due to their microstructural instability, a consequence of the high
internal energy stored as crystalline defects (vacancies and dislocations). In order
to study the mechanical behavior at low temperature and design severely
deformed microstructures that are stable in the long term, the present work
investigated the Cu-0.8Cr-0.07Zr alloy after Equal Channel Angular Pressing
(ECAP) processing at -80 °C, in terms of microstructural stability, comparing it to
pure copper processed under the same conditions. Regarding the mechanical
behavior of the studied alloy, it was defined that there is the occurrence of both
dislocation slipping and mechanical twinning, depending on the level of
deformation and temperature. Post-ECAP results indicated that for the Cu-0.8Cr0.07Zr alloy it was possible not only to overcome the obstacle of microstructural
instability by post-processing cryogenic ECAP processing, but also to provide an
additional increase in the yield stress (+ 22%). Both effects were possible due to
the formation of chromium-rich precipitates on a severely deformed
microstructure, which hindered the movement of dislocations and grain
boundaries. Thus, this set of results allowed us to understand about the
strengthening mechanisms, microstructure evolution and thermal stability of the
Cu-0.8Cr-0.07Zr alloy, useful for practical applications of materials processed by
cryogenic DPS.
Colecciones
El ítem tiene asociados los siguientes ficheros de licencia: