Dresden 2014 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session

MM 18.31: Poster

Monday, March 31, 2014, 18:00–20:00, P4

Structure and thermal stability of HPT-processed Cu-16 at.%Al — •Nazar Ibrahim, Martin Peterlechner, Sergiy Divinski, and Gerhard Wilde — Institute of Materials Physics, Westfälische Wilhelms-University Münster,Wilhelm-Klemm-Str. 10, 48149 Münster

Severe plastic deformation is an effective tool for production ultrafine grained materials with extraordinary mechanical properties, corresponding to a high strength and relatively good ductility. In this work, structure modification by high pressure torsion (HPT) and the thermal stability of the resulting microstructure are investigated for the Cu16 at.% Al alloy. For this alloy, a propensity for five-fold twinning has recently been reported [X.H. An, et al., Scripta Materialia 64 (2011) 249]. Disks with a thickness of 0.8 mm and diameter of 10 mm were processed via HPT for 2, 5, 10 and 20 revolutions at room temperature under hydrostatic pressure levels of 2, 4 and 6 GPa and a rotational speed of 1 rpm. Structural and thermal analyses were carried out using X-ray diffraction, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The DSC experiments using constant heating rates showed two exothermic peaks in the temperature range from 30°C to 450°C. After HPT a highly distorted structure was observed, including dislocations, fragmented grains and twins. Due to the low stacking fault energy in Cu84Al16, twinning makes a significant contribution to plasticity during HPT. The results are discussed with respect to the reported five-fold twinning in this alloy.