Lecture
WEB Magnetic nanostructure of a Co-Cu alloy processed by high-pressure torsion
Tuesday (22.09.2020) 11:50 - 12:05 S: Structural Materials 1 Part of:With severe plastic deformation, grain sizes in the nanocrystalline regime can be obtained, while the material retains its shape. In particular, high-pressure torsion exhibits the advantage of continuously applying a desired amount of strain. This study deals with intermixing of the thermodynamically non-miscible components Co and Cu, achieved by high-pressure torsion with a focus being on Co-rich compositions. The bulk samples are investigated regarding their microstructural as well as magnetic properties, whereas the main emphasis of this study is on the correlation of both. Starting with a mixture of conventional powders, a single-phase supersaturated solid solution with nanocrystalline grains is obtained. Microstructural investigations are performed by electron microscopy and X-ray diffraction. To investigate the thermal stability, various annealing treatments are carried out, revealing a persisting nanocrystallinity up to a homologous temperature of 0.6. The dc-magnetic properties are investigated by SQUID-magnetometric measurements, showing soft magnetic behavior in a wide temperature range of annealing treatments. The temperature stability of the soft magnetic phase is studied by quantitative investigations of the magnetic nanostructure using magnetic force microscopy. A correlation of the magnetic properties with findings from microstructural investigations shows a decreasing domain size with increasing annealing temperature, revealing the demixing behavior of the supersaturated solid solution.
