Extraction of flow curves from dynamic nanoindentation tests using a multiple sharp tip approach

Forschungsoutput: Forschung - (peer-reviewed)Vortrag

Abstract

Instrumented indentation is an efficient technique to extensively characterize the mechanical behavior of materials. Modern dynamic indentation techniques, such as the continuous measurement of stiffness by a superimposed oscillating force signal, allow to further exploit indentation experiments resulting in highly reliable results. However, hardness differences between static and dynamic tests have been noted in the past. We will demonstrate that these deviations mainly result from a non-constant strain-rate during static test profiles, particularly during hold segments at peak load. This will lead to distinct errors in obtained mechanical properties for materials with enhanced strain-rate sensitivity, which could by mistake be ascribed to the use of the continuous stiffness measurement. Considering this fact, we demonstrate on the example of nickel and tungsten, with microstructures ranging from single crystalline to nanocrystalline dimensions, how flow curves can be extracted from nanoindentation by using four pyramidal tips with varying apex angle. It is shown that by using appropriate definitions of indentation stress and strain and considering the indentation size effect the obtained values exceedingly coincidence with reference data determined by uniaxial tests.

Details

OriginalspracheEnglisch
StatusVeröffentlicht - 15 Mai 2017
EreignisArbeitskreistreffen "Rasterkraftmikroskopie und nanomechanische Methoden" - Aachen, Deutschland

Konferenz

KonferenzArbeitskreistreffen "Rasterkraftmikroskopie und nanomechanische Methoden"
LandDeutschland
OrtAachen
Zeitraum15/05/1716/05/17