Mechanical Response of Materials Investigated through Novel In-situ Experiments and Modeling: Session III
Sponsored by: TMS Structural Materials Division, TMS Functional Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Thin Films and Interfaces Committee
Program Organizers: Saurabh Puri, VulcanForms Inc; Amit Pandey, Lockheed Martin Space; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization; Dongchan Jang, Korea Advanced Institute of Science and Technology; Shailendra Joshi, University of Houston; Minh-Son Pham, Imperial College London; Jagannathan Rajagopalan, Arizona State University; Robert Wheeler, Microtesting Solutions LLC; Josh Kacher, Georgia Institute of Technology
Wednesday 8:30 AM
March 22, 2023
Room: Aqua 310B
Location: Hilton
Session Chair: Minh-Son Pham, Imperial College London; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization
8:30 AM Invited
In-situ Micro-tensile Studies on the Effects of Ion Irradiation on the Mechanical Properties of Small-grained Alloys: Dhriti Bhattacharyya1; Alan Xu1; Tao Wei1; Mihail Ionescu1; 1Australian Nuclear Science and Technology Organization
Ion irradiation is an attractive alternative to neutron irradiation for studying the effects of radiation damage on materials as it imparts relatively high doses (several dpa) in a short time frame (days) without activating the samples. However, the thin layer of material radiated by this technique requires the employment of small-scale testing methods such as micro-mechanical testing. This technique is more suitable for the assessment of mechanical properties when the grain size is small compared with the sample size. Here, an overview of a series of studies on the effects of ion irradiation on the mechanical properties of three different materials with small grains (<2 μm is presented. These studies on an oxide dispersion strengthened (ODS) steel MA957, pure Ni and Ni-SiC dispersion strengthened alloy employ in situ micro-tensile testing inside the scanning electron microscope. The results are discussed in terms of their relevance to bulk mechanical properties.
9:00 AM Invited
On the Kink-band Formation in True and Brittle Micas: Hemant Rathod1; Andreas Kronenberg1; Miladin Radovic1; Ankit Srivastava1; 1Texas A&M University
Micas are ubiquitous in earths lithosphere and they greatly influence the overall crustal deformation. In the presence of high temperature, pressure and mineral rich fluids, the composition of mica can change overtime by the process known as isomorphic substitution. However, even after decades of thorough investigation of mechanical behavior of micas, the effect of isomorphic substitution on the formation of kink-bands in mica has remained unresolved. Herein, we analyze the formation of kink-band in a true and a brittle mica via novel in-situ SEM experiments. Our results show that mica with low T-O-T structure charge deforms readily by large layer rotations and extensive thin kink-band formation without any sign of transverse layer cracks, whereas mica with high T-O-T structure charge exhibits limited layer rotation, fewer kink-bands and extensive transverse layer cracking. The complete result of this investigation will be discussed in this presentation.
9:30 AM
Micropillar Compression Testing of Proton Irradiated NiCr2 Alloy: Chaitanya Peddeti1; Andrew Scott1; 1UC Berkeley
How radiation affects the micro-mechanical properties of metals is crucial to study as it provides avenues to parameterize radiation damage, as well as add to the existing database of radiation effects on metals. SRIM was used to calculate the penetration depth of protons into NiCr2 to ensure samples were fabricated in the radiation zone. EBSD was used to determine grain orientation and location within the radiation zone. Micropillars were fabricated using a Focused Ion Beam within a singular grain. Mechanical properties were measured with in-situ SEM compression tests to measure hardness. At 1.5 DPA proton irradiation, we noticed an increase in hardness of the alloy and decrease in strain that led to failure. The increased hardness and values observed in the irradiated sample is evidence of radiation hardening due to increased defect concentration, and the decreased strain-to-failure value isevidence of decrease in ductility.
9:50 AM
An In-situ SEM Study on Hydrogen Embrittled Alloy 718: Hamza Khalid1; Bilal Mansoor2; 1Texas A&M University; 2Texas A&M University at Qatar
Nickel alloy 718 drastically loses ductility and fracture toughness in environments containing hydrogen. Hydrogen embrittlement (HE) in nickel alloy 718 is complex and has a dependence on the microstructure of the alloy, intensity and duration of hydrogen exposure and the mode of mechanical loading applied. Previous work has shown a correlation of the presence of precipitate phases with a higher susceptibility to HE. Other work has shown lattice defects like certain GBs and dislocation slip bands (DSBs) causing crack initiation and propagation. We subject solutionized and aged tempers of hydrogen pre-charged alloy 718 to in situ tensile tests in the SEM and directly observe the deformation, crack initiation and propagation and eventual fracture. This technique allows us to image how the specimen deforms in elastic, plastic and post-necking regions. Based on these results, we explain the dependence of deformation and fracture of hydrogen embrittled alloy 718 on its microstructure.
10:10 AM Break
10:30 AM
Dynamic Cryo-mechanical Properties of Dewetted Nickel Microparticles: Barbara Bellon Lara1; Gerhard Dehm1; Rajaprakash Ramachandramoorthy1; 1Max-Planck-Institut für Eisenforschung
The working conditions of micro/nano-scaled metallic systems have a crucial influence on their mechanical properties. However, they remain unexplored on microscaled metals under extreme loading conditions, like high strain rates (0.1/s to 10000/s) and extreme temperatures (-150ºC to 600°C). Recent studies under quasi-static loading conditions show that single-crystalline microscale metals exhibit strength close to the theoretical values. However, under extreme conditions, there is a lack of information on the mechanical properties and deformation mechanisms We plan to bridge this gap by performing in-situ compressions of single-crystalline nickel microparticles at strain rates from 0.005 to 10000/s, at room and cryo temperatures inside a scanning electron microscope. The microparticles were obtained via solid-state dewetting of nickel thin films and their microstructure was characterized using a variety of electron-based advanced microscopy techniques. In summary, a complete deformation map of pristine microscale nickel will be presented as a function of temperature and strain rate.
10:50 AM
The Effect of Heat Treatment on Full-field Damage Evolution in Laser Powder Bed Fusion-manufactured 316L Stainless Steel: Marissa Linne1; Margaret Wu1; Tatu Pinomaa2; Anssi Laukkanen2; Nathan Barton1; Thomas Voisin1; 1Lawrence Livermore National Laboratory; 2VTT Technical Research Centre of Finland
Additively manufactured 316L stainless steels produced by laser powder bed fusion (L-PBF) have favorable high strength and high ductility compared to conventional steels, due to a hierarchically heterogeneous microstructure, which enables progressive work hardening. Modeling this complex microstructural behavior requires statistical deformation data. To address this, in the presented work, strain evolution of L-PBF 316L stainless steel was investigated with microscale resolution over mm-scale fields of view using electron backscatter diffraction and SEM-enabled digital image correlation. In-SEM tensile tests were conducted on as-printed and heat-treated 316L samples. Heat treatment and dislocation structure removal affects the relative contributions of twinning vs. slip deformation mechanisms. The results of this study help inform models to accurately simulate the differences in hardening behavior observed between as-built and heat-treated L-PBF-manufactured 316L stainless steel. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
11:10 AM
Characterization of Deformation Mechanisms Near Grain Boundaries in Mg Alloys by Means of In-situ EBSD and High-resolution Digital Image Correlation: Biaobiao Yang1; Maral Sarebanzadeh2; Eugenia Nieto-Valeiras2; Alberto Orozco-Caballero3; Javier Llorca2; 1IMDEA Materials Institute & Central South University; 2IMDEA Materials Institute & Technical University of Madrid; 3Technical University of Madrid
The deformation mechanisms near grain boundaries in different Mg alloys were ascertained by means of a combination of different experimental techniques during mechanical tests within the scanning electron microscope. In particular, the active slip(s) system(s) were determined by means of slip trace analysis while the nucleation and growth of twins was determined by means of in situ electron backscatter diffraction. In addition, the local stress state at selected locations was obtained through high-resolution digital image correlation. The information was used to rationalize the effect of grain and twin boundaries on the deformation mechanisms of Mg alloys with different texture. Furthermore, the differences between the global and the local Schmid factors (that determine the most active slip system and twin variant) were investigated and optimum geometrical criteria to predict slip transfer and twin/slip and slip/twin transfer at grain boundaries were determined.
11:30 AM
In-situ Nano-indentation of a Pt Nanoparticle Combined with Bragg Coherent X-ray Diffraction Imaging.: Sarah Yehya1; Thomas Cornelius2; Marie-Ingrid Richard3; Felisa Berenguer1; Eugen Rabkin4; Olivier Thomas2; Stéphane Labat2; 1Synchrotron SOLEIL; 2AMU - CNRS; 3CEA of Grenoble; 4Technion Institute of Technology
Defects in nanocrystals can dramatically alter the physical and chemical behavior of materials. The understanding of defect behavior is thus crucial to enhance material properties. Here we report on defect characterization in a 400 nm Pt nanoparticle from synchrotron experiment that combines in-situ nano-indentation using a custom-built AFM with Bragg Coherent X-ray Diffraction Imaging. The latter is an innovative lens-less imaging technique that allows for 3D characterization of morphology and strain with a 10 nm 3D spatial resolution and picometer sensitivity of lattice displacement field. The coherent diffraction pattern of a single 111 reflection is recorded before, during and after indentation. The reconstructed Pt particle in 3D evidences that defects were induced during indentation and the stress required to generate such defects was determined. Furthermore, multiple-Bragg reflections were recorded on the same particle to determine the full 3D strain tensor. This result is confirmed by finite element simulation.
11:50 AM Invited
The Dynamic Signatures of Strain Bursts in Metals: Mostafa Omar1; Jaafar El-Awady1; 1Johns Hopkins University
Comprehensive understanding of deformation in metals is contingent on our knowledge of dislocation dynamics and its intermittent behavior. In-situ micromechanical testing techniques are incapable of resolving spatially and/or temporally overlapping activities. In this work, we extend the use of Acoustic emissions technique (AE) to microscale experiments to investigate avalanches’ features which were elusive from micro-mechanical testing alone. AE technique was concurrently used with in-situ compression for Ni micropillars to study dislocation avalanches with respect to the AE waves they generate. Spectral investigation showed a limited frequency range for the dislocation activities. The high temporal resolution associated with the AE technique made it possible to resolve batches of wavelets within the same strain burst. Hence, avalanches activities correlations between features including pre-shock and after-shock behavior, frequency evolution, energies, and velocities were revealed. In addition, the strain-level and the strain burst size were found to have a significant impact on these features.