SKM 2021 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 3: Topical Session Interface-Dominated Phenomena - Defect Structures and Mechanical Properties

MM 3.2: Vortrag

Montag, 27. September 2021, 13:45–14:00, H2

How the interface type manipulates the thermomechanical response of nanostructured metals: A case study on nickel — •Oliver Renk¹, Verena Maier-Kiener², Christian Motz³, Daniel Kiener², Jürgen Eckert¹, and Reinhard Pippan¹ — ¹Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben, Austria — ²Montanuniversität Leoben — ³Saarland University, Germany

The presence of interfaces with nanoscale spacing significantly enhances the strength of materials, but also changes the rate controlling processes of plastic flow. Due to the confined grain volumes, intragranular dislocation-dislocation interactions are replaced by emission and absorption of dislocations from and at the interfaces. Both processes not only depend on the interfacial spacing, but also on the interface structure. The present study attempts to rationalize this effect by investigating the thermomechanical behavior of samples consisting of three different interfaces. Nickel samples with predominant fractions of low- and high-angle as well as twin boundaries with a similar average spacing of 150 nm are investigated using high temperature nanoindentation strain rate jump tests. Depending on the interface structure, hardness, strain rate sensitivity and apparent activation volumes evolve different with temperature. While in case of high-angle boundaries for all quantities a pronounced thermal dependence is found, the other two interface types behave almost athermal. These differences can be rationalized based on the different interfacial diffusivity, affecting the predominant process of interfacial stress relaxation.