Materials World Network: Mechanisms leading to nanometer-sized materials

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Deformation induced grain refinement has been revealed in pure Cu by rolling at ambient and cryogenic temperature and low temperature annealing. In addition, Zn decreases the stacking fault energy (SFE) from 78 (for pure Cu) to 14 mJ/m2 (Cu-30 wt.% Zn) and enhances the grain refinement. In this project, nano-/ultrafine grained Cu-/Cu-Zn alloys will be synthesized by rolling and low temperature annealing, in order to overcome dimension limitations of specialized critical mechanical tests for strength and ductility, which are poorly understood for such NC/UFG materials. Characterization of the microstructure will be performed down to the atomic level by thorough and systematic analysis; and mechanical properties of these materials will be studied under tension, compression and torsion. In-situ deformation studies under scanning and transmission electron microscopic observation will be performed to reveal the deformation mechanisms at different length-scales. The nano-/ultrafine structures obtained by various processing routes (rolled/annealed samples prepared at IFW and specimens produced by ball milling (NCSU) and equal channel angular pressing/ high pressure torsion (UV)) will be compared in order to reveal the influence of processing induced structural defects on the ease of grain refinement in Cu-/Cu-Zn alloys with different SFE and deformation mechanisms as a function of grain size and SFE. The influence of alloy composition and processing conditions, i.e., rolling temperature, severity of deformation, on nanostructure development, and final grain size will be compared in these Cu/Cu-Zn alloys with different SFE.