30 Years of Nanoindentation with the Oliver-Pharr Method and Beyond: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Nanomechanical Materials Behavior Committee
Program Organizers: Verena Maier-Kiener, Montanuniversitaet Leoben; Benoit Merle, University of Kassel; Erik Herbert, Michigan Technological University; Samantha Lawrence, Los Alamos National Laboratory; Nigel Jennett, Coventry University

Monday 5:30 PM
February 28, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center

H-1: High-speed Indentation for 3D Mapping of Nanoporous Gold: Kerry Baker1; T Balk1; 1University of Kentucky
    Improvements to nanoindentation techniques have allowed for faster data collection and expanded methods for data interpretation. Techniques, such as Nanoblitz 3D, have allowed for mapping material properties of a selected sample area at high speeds. In order to create these maps, the indent spacing must be sufficiently distanced so that previous indents do not influence subsequent indents. However, the indents must be close enough to understand the local variations of the sample. Previous work has been done to find the optimal ratio of indent spacing to indent depth (d/h ratio) for bulk materials. This work will focus on how nanoporous structures influence the d/h ratio. Nanoporous gold samples are created and coarsened to various ligament sizes in order to be tested at multiple d/h ratios to identify the optimal spacing. Preliminary findings have shown that the ideal d/h ratio for nanoporous structures is similar to bulk metallic materials.

H-2: Investigating the Strain Rate Dependence of Hardness of Cu/Mo Nanolaminate Films Using Conventional and High Strain Rate Nanoindentation Methods: Wesley Higgins1; Christopher Walker1; Benjamin Hackett1; George Pharr1; 1Texas A&M University
    Recent advances in commercially available nanoindentation systems make it possible to measure indenter displacements at up to 100 kHz data acquisition rates and thereby conduct nanoindentation tests at high strain rates. Such a system was used to examine the strain rate dependence of the hardness of Cu/Mo nanolaminate thin films comprised of two bilayer thicknesses of 5 and 100 nm as well as monolithic films of Cu and Mo. However, the commercial system was not designed with high strain rate testing in mind, resulting in various limitations in the measurements. To circumvent this, the same films were also tested using a new, custom-designed nanoindentation system that incorporates a hexapod translation stage and gantry for very high frame stiffness and a laser interferometer for measuring tip displacement at rates as high as 10 MHz. Results from the two systems are compared and discussed in terms of the relative advantages and limitations.

H-3: Nanoindentation of Semi-crystalline and Amorphous Thermoplastics: Petra Christoefl1; Caterina Czibula2; Michael Berer1; Christian Teichert3; Gerald Pinter3; Gernot Oreski1; 1PCCL; 2Graz University of Technology; 3Montanuniversitaet Leoben
    The investigation of polymers with nanoindentation (NI) is challenging since the deformation during loading is time-dependent, which can be described by viscoelasticity. Creep experiments can be combined with viscoelastic material modelling to better understand the time-dependent material behavior of polymers. In this study, spring-dashpot models will be used to describe the viscoelastic behaviour of amorphous as well as semi-crystalline polymers. The influence of morphological structures such as spherulites or crystal-lamellae of semi-crystalline polymers on localized NI depth-force behaviour is discussed controversially in literature. Hence, the main objective of this study is to investigate the influence of semi-crystallinity on NI results obtained for polyoxymethylene (POM) in comparison to amorphous poly(methyl methacrylate) (PMMA). Furthermore, the NI results will be compared with macroscopic compression test results.