30 Years of Nanoindentation with the Oliver-Pharr Method and Beyond: Characterization of Advanced Materials Systems
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
Thursday 2:00 PM
March 3, 2022
Room: 259B
Location: Anaheim Convention Center
Session Chair: Karsten Durst, Technical University Darmstadt; Graham Cross, Trinity College Dublin
2:00 PM Invited
NOW ON-DEMAND ONLY – Best Practices for Berkovich Nanoindentation in Hard Biological Tissues: Joseph Jakes1; Donald Stone2; 1USDA FS Forest Products Laboratory; 2University of Wisconsin - Madison
Nanoindentation offers a unique but challenging opportunity to probe the mechanical properties of micron-scale features in hard biological tissues like wood and bone. However, traditional nanoindentation methods were developed for hard, inorganic materials. These traditional methods also tacitly assume specimens are rigidly supported, homogeneous, and semi-infinite. These assumptions are violated in biological materials. This paper presents improved nanoindentation methods, including experimental protocols and an analysis algorithm, specifically designed to improve the accuracy of Berkovich nanoindentation measurements in complex biological tissues. The improved methods are built off the traditional methods. But the key is to assess mechanical properties as a function of size in each nanoindentation location. This size-dependent data is used in the analysis algorithm to correct the data for structural compliances arising from nearby edges and specimen-scale flexing, as well as to detect potential errors caused by issues like surface detection errors, displacement drift, surface tilt, and dirty probes.
2:25 PM
Nanoindentation of Supercrystalline Nanocomposites: Diletta Giuntini1; Shiteng Zhao2; Buesra Bor3; Cong Yan3; Alexander Plunkett3; Gerold Schneider3; 1Eindhoven University of Technology; 2University of California Berkeley; 3Hamburg University of Technology
Supercrystalline nanocomposites are a rising category of nanoarchitected materials, resulting from the self-assembly of functionalized nanoparticles into long range order architectures. Being typically explored in the field of chemistry, their mechanical behavior is largely unexplored — a lack of information that hampers their multiple potential functional applications (in optoelectronics, catalysis, energy transfer and storage, and more). Nanoindentation is ideally suited to tackle this issue. We present here a thorough nano and micro-mechanical characterization of ceramic-organic supercrystalline nanocomposites. An extreme boost in strength, hardness and stiffness is observed after inducing the crosslinking of the organic phase. Time-dependent behavior is observed via creep and fatigue studies. Many fundamental questions are addressed, inspiring solutions to fine-tune the mechanical behavior of these promising new generation of nanostructured materials.
2:45 PM
Characterization of Grain Boundaries in Geological Materials Using Micromechanical Testing: Diana Avadanii1; Lars Hansen2; Katharina Marquardt3; Ed Darnbrough1; David Armstrong1; Angus Wilkinson1; 1University of Oxford; 2University of Minnesota; 3Imperial College London
Olivine is a key geological material influencing large-scale, long-term planetary deformation processes on rocky planets. In the past three decades, nanoindentation has been deployed as a powerful technique to study olivine mechanics. Previous studies have emphasized the importance of grain-size effects. However, most of our understanding of the role of grain boundaries in deformation of olivine is inferred from comparison of experiments on single crystals to experiments on polycrystalline samples.To directly observe and quantify the mechanical properties of olivine grain boundaries, we conduct micromechanical tests on well characterised bicrystals. We perform room-temperature spherical and Berkovich nanoindentation and in-situ micropillar tests at 700°C. We observe that certain grain-boundary configurations act as sites for initiating microplasticity. The experiments demonstrate that, under these conditions, grain boundaries are stronger than the grain interior. These observations provide a basis for incorporating grain-boundary effects in the next generation of constitutive models for geological materials.
3:05 PM
A Comparative Study of Fracture Toughness Measurements in Two Silicate Glasses Using Nanoindentation: Yvonne Dieudonne1; George Pharr1; 1Texas A&M University
The cracking behavior of silicate glasses has been studied using nanoindentation with triangular pyramidal indenters with centerline-to-face angles in the range of cube corner (35.3°) to Berkovich (65.3°) as well as Vickers indenters. Two different glass structures have been analyzed and compared - an anomalous glass (fused quartz) and a normal glass (soda lime silicate), which deform primarily by densification and shearing processes, respectively. These different deformation processes lead to different stress fields around the hardness impressions resulting in different cracking morphologies. Nanoindentation at various loads (e.g., 3 mN -20 N) and subsequent FIB-cross-sectioning was used to examine the morphology of the cracks and whether they are median-radial type, which are initiated underneath the indentation impression, or Palmqvist cracks, which start near the surface. Results show that the difference in cracking behavior may have important implications for determining fracture toughness by indentation cracking methods.
3:25 PM Break
3:45 PM
Nanoindentation of NiTi Shape Memory Alloys: Gunther Eggeler1; 1Ruhr-Universität Bochum
When exploring the reaction of NiTi based shape memory alloys to nanoindentation, one has to take elementary processes into account, which are related to the nature of the martensitic transformation. In pseudoelastic materials, stress induced martensitic transformations need to be considered. Pseudoplastic materials, on the other hand, show detwinning of their martensitic microstructure. High stress concentrations associated with sharp Berkovich nano indenter tips promote dislocation plasticity. This affects the reversibility of the shape memory effects, which also depends on the presence/absence of coherent precipitates. The contribution highlights nanoindentation research on NiTi shape memory materials which was performed between 2005 and 2015 at the Ruhr-University Bochum, during and shortly after the running period of the collaborative research center SFB 459 on shape memory materials, funded by the German Research Association (DFG). It also discusses recent and related work from other groups and highlights areas in need of further work.
4:05 PM
Determination of Constitutive Properties for Shape Memory Alloys from Nanoindentation Response: Xuesong Gao1; Daniel Hong1; Harshad Paranjape2; Wei Zhang1; Peter Anderson1; 1The Ohio State University; 2Confluent Medical Technologies, Inc
This work reports on a Bayesian inference approach, combined with finite element simulations of Berkovich nanoindentation, to determine the constitutive properties of shape memory materials. This builds on and extends prior efforts for isotropic, elastic-plastic materials. For shape memory materials (SMAs), the response is complicated by a stress-induced, reversible phase transformation that differs for tension versus compression and depends on crystallographic orientation and prior plastic deformation. To tackle this complexity, a high fidelity finite element model incorporating superelastic-plastic constitutive relation was developed and validated. Then numerous simulations were used to predict the nanoindentation response for a variety of SMAs with different constitutive parameters. The large dataset was used to train a Bayesian inference model and test it. The resulting inverse framework for SMAs predicts the stress-strain response from nanoindentation data, provides insight on the Oliver-Pharr formalism, and demonstrates the benefits of conducting repeated (2-cycle) versus conventional single indentation testing.
4:25 PM
Assessing Segregation-induced Softening in Nanocrystalline Stabilized NiP by Nanoindentation: Ilias Bikmukhametov1; Thomas Koenig1; Garritt Tucker2; Gregory Thompson1; 1University of Alabama; 2Colorado School of Mines
Phosphorous segregation to grain boundaries (GBs) in NiP nanocrystalline (NC) thin films has been shown to retard elevated temperature grain growth. In the current work, we studied the effect of P segregation on the mechanical properties using nano-indentation with post mortem transmission electron microscopy (TEM), including precession electron diffraction (PED), to reveal the deformation-induced microstructural changes. When P was found in solution, the NC film exhibited approximately 20 % higher average hardness than those films that underwent a thermal anneal to partition the P to the GBs. No evidence of deformation-induced grain growth was seen in either case. The interplay of solid solution strengthening and GB-mediated deformation is discussed. Furthermore, five-fold twin arrangements or quintuple twin junctions were found in the film structures, having a high density in Ni-1%P films and almost being absent in the Ni-4%P film.