Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 8: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Segregation and Embrittlement II

MM 8.5: Talk

Monday, March 20, 2017, 12:45–13:00, BAR 205

Macroscopic and microscopic investigation of Sulphur - induced embrittlement in Copper — •Thorsten Meiners, Zirong Peng, Christian H. Liebscher, and Gerhard Dehm — Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf

Sulphur (S) is a common impurity element, which has a very low solubility in copper alloys (Cu) and is attributed to cause grain boundary (GB) embrittlement by segregating to the boundaries. In our study, macro-tensile tests at room temperature (RT), 200 °C and 400 °C are applied to investigate embrittlement of polycrystalline Cu alloys containing 14, 27 and 7900 ppm of S, named alloy 1, 2 and 3 here. Alloy 1 shows a reduction in ductility of 18% from RT to 400 °C. Compared to that, alloy 2 shows a reduction in ductility of 29% at RT and 70% at 400 °C and alloy 3 58% at RT and 67% at 400 °C. The grain size was determined to about 2 mm using electron backscatter diffraction. Alloy 1 is free of precipitates and high resolution transmission electron microscopy (TEM) and atom probe tomography reveal no segregation of S to random GBs. In alloy 2, small precipitates on the order of 50nm can be established at the GBs and within the grains with scanning electron microscopy. Alloy 3 shows a dendritic structure where large low chalcocite Cu2S precipitates (several micro meters) are located at the dendrites and small precipitates (about 50 nm) are located in interdendritic regions. For the alloys 2 and 3 high-resolution TEM does also not confirm segregation of S to the random GBs and the embrittlement of the alloys is mainly related to the presence of precipitates.