Berlin 2018 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 18: Diamond II + Poster

KFM 18.10: Poster

Wednesday, March 14, 2018, 16:50–17:30, E 124

Cross-sectional Microstructure, Stress Gradients, and Mechanical Properties in Diamond Films Revealed by X-ray Nanodiffraction and Microcantilever Testing — David Gruber¹, •Nicolas Wöhrl², Hadwig Sternschulte³, Manfred Burghammer⁴, Juraj Todt⁵, and Jozef Keckes¹ — ¹Department für Materialphysik, Montanuniversität Leoben, Austria — ²Faculty of Physics and CENIDE, University of Duisburg-Essen, Germany — ³Fakultät für Allgemeinwissenschaften, Hochschule Augsburg, Germany — ⁴ESRF, Grenoble, France — ⁵Erich-Schmidt-Institut, Austrian Academy of Sciences, Leoben, Austria

Ultrananocrystalline diamond (UNCD) films consist of randomly oriented diamond grains embedded in an amorphous C:H matrix. Usually, the grain size is determined by XRD or TEM, revealing information from the total UNCD film or only locally from selected areas with low statistics. Here, we present a cross-sectional X-ray nanodiffraction study of diamond multi-layers with varying grain size from microcrystalline diamond to UNCD. X-ray nanodiffraction was performed in transmission geometry using a beam diameter of 30 nm. The sample was scanned in equidistant steps, revealing depth gradients of texture, grain size and residual stress. Young's modulus and fracture stress in both UNCD and microcrystalline sublayers were measured with micro cantilevers fabricated by FIB milling. A cross-sectional nanoindenter-based mapping of Young's modulus was carried out on a slice of the layer system prepared by FIB. The results show complex gradients of microstructure, stress state and mechanical properties.