Article
Chemistry, Physical
Yi Wang, Yihe Zhang, Rory Gover, Jie Yang, Yingyan Zhang
Summary: Graphene has excellent physical properties, but its two-dimensional structure limits its application as reinforcing fillers in composites. In this study, an origami technique was used to improve the flexibility of graphene. Molecular dynamics simulations showed that graphene origami (GOri) can withstand higher loads and indentation depths than pristine graphene. The flexibility and strength of GOri can be further enhanced in the bilayer format. This study provides insights into the failure mechanisms and mechanical properties of GOri for graphene-based impact protection applications.
Article
Multidisciplinary Sciences
Mario Castro, Samuel E. Baltazar, Javier Rojas-Nunez, Eduardo Bringa, Felipe J. Valencia, Sebastian Allende
Summary: The mechanical and magnetic properties of polycrystalline nanoframes were investigated using atomistic molecular dynamics and micromagnetic simulations. The magneto-mechanical response of Fe hollow-like nanocubes was addressed by nanoindentation. The results showed that the deformation of a nanoframe is dominated by filament bending at lower strains, leading to nanoframe twisting and increased coercivity. This increase occurs because the mechanical deformation changes the shape of the nanoframe, driving the system to more stable magnetic states. These findings are important for the design of magnetic devices that utilize mechanical deformation to tailor the magnetic response of nanoscale solids.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Multidisciplinary
Kaushik Dey, Surojit Bhunia, Himadri Sekhar Sasmal, C. Malla Reddy, Rahul Banerjee
Summary: This study investigates the mechanical behavior of different types of COF thin films by controlling the internal order and self-assembly of building blocks, revealing that defect density and the nature of supramolecular interactions play a significant role in determining the stress-strain behavior of the films.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Multidisciplinary Sciences
Qiubo Zhang, Zhigang Song, Yu Wang, Yifan Nie, Jiawei Wan, Karen C. Bustillo, Peter Ercius, Linwang Wang, Litao Sun, Haimei Zheng
Summary: This study investigates the nucleation and propagation mechanisms of twinning in Pb individual nanocrystals, revealing that the basic unit of movement for twin propagation is a double-layer swap motion. The swap motion is a phonon eigenmode of the face-centered cubic crystal structure of Pb, and it is enhanced by the quantum size effect of nanocrystals.
Article
Materials Science, Multidisciplinary
Shawkat Imam Shakil, Leandro Gonzalez-Rovira, Leticia Cabrera-Correa, Juan de Dios Lopez-Castro, Miguel Castillo-Rodriguez, F. Javier Botana, Meysam Haghshenas
Summary: This paper presents a comprehensive investigation into the correlation between microstructural features and macroscopic properties of laser powder bed fused Scalmalloy(R). It shows that the strength of the alloy improves significantly in the heat-treated condition due to the precipitation of secondary phases; however, the grain size and texture remain relatively unchanged.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Hassaan Zafar, Shafique M. A. Khan, Numan Abu-Dheir
Summary: This study investigates the evolution of the dislocation structure during nano-indentation using a three-dimensional multi-scale discrete dislocation plasticity model. The results show that the dislocation activity, especially cross-slip activity, is significantly influenced by the initial configuration of the dislocation sources, and the crystal orientation affects the topography of the nano-indented surface.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Engineering, Mechanical
Dongpeng Hua, Qiaosheng Xia, Yeran Shi, Qing Zhou, Shuo Li, Xiangtao Deng, Haifeng Wang, Zhaodong Wang
Summary: The deformation response of the cementite/ferrite (Fe3C/alpha-Fe) interface under a mechanical load was investigated using molecular dynamics simulation. The results revealed that the interface effectively hinders shear deformation propagation and relaxes strain/stress concentration. With increasing indentation depth, the cementite phase undergoes an amorphous transformation and rejuvenation, while the ferrite phase undergoes a phase transformation to HCP, synergistically enhancing the plasticity of pearlite. Furthermore, the study shed light on the underlying origin for the decreased growth rate of the friction coefficient with increasing friction depth and the periodic changes in tribological properties in the scratch direction.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
H. Zhang, F. De Luca, H. Wang, K. Mingard, M. Gee
Summary: The deformation behavior of pure tungsten carbide (WC) was studied using nanoindentation tests. Different specimen preparation processes led to elastic to plastic deformation at different threshold loads, and staircase deformation was caused by dislocation motion and the formation of slip bands. Displacement discontinuities in the load-displacement curves were associated with dislocation loop nucleation at or near the theoretical shear strength.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
B. L. Hackett, P. Sudharshan Phani, C. C. Walker, W. C. Oliver, G. M. Pharr
Summary: A new testing system and techniques have been developed to measure the hardness of materials at very high indentation strain rates. The system includes a laser interferometer that records indenter displacements at a frequency of 1.25 MHz, allowing for the determination of indentation load-depth curves and hardness. The system was used to study the behavior of fused silica and aluminum, showing that the hardness of fused silica is insensitive to strain rate, while the hardness of aluminum increases significantly at high strain rates.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Chemistry, Physical
Juan A. de la Rosa Abad, Alejandra Londono-Calderon, Eduardo M. Bringa, German J. Soldano, Sergio A. Paz, Ulises Santiago, Sergio J. Mejia-Rosales, Miguel Jose Yacaman, Marcelo M. Mariscal
Summary: This study investigates the atomistic mechanical response of Au-Pd core-shell and Pd nanocubes under indentation using molecular dynamics simulations, comparing the results to experimental observations. The research shows that different deformation mechanisms occur in core-shell and single-crystalline nanocubes, suggesting potential for tuning mechanical properties at the nanoscale by combining metals in a core-shell configuration.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Materials Science, Multidisciplinary
Sergey N. Dub, Cetin Haftaoglu, Vitaliy M. Kindrachuk
Summary: The onset of plasticity in a single crystal C-60 fullerite was investigated through nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation was observed as pop-in events on loading curves, with computed resolved shear stresses for the octahedral slip systems. Finite element analysis reproduced elastic loading until the first pop-in, with the estimated C-60 theoretical shear strength being about 1/11 of the shear modulus on {111} planes.
JOURNAL OF MATERIALS SCIENCE
(2021)
Article
Construction & Building Technology
Bao Jian Zhan, Dong Xing Xuan, Chi Sun Poon, Karen L. Scrivener
Summary: Carbonation treatment enhances the structure of C-S-H, leading to improved nano-indentation modulus and microhardness at the edge zone, contributing to the enhanced macro compressive strength of the carbonated sample. The heterogeneous distribution of carbonation products in the sample was observed, but the reinforcement of C-S-H prevailed over the alteration induced by carbonation treatment.
CEMENT AND CONCRETE RESEARCH
(2021)
Article
Materials Science, Ceramics
Yasuhito Matsubayashi, Hiroki Tsuda, Takashi Nagoshi, Jun Akedo
Summary: Aerosol deposition is a promising technique for preparing insulation coatings with micrometer thickness. In this study, alumina films fabricated by aerosol deposition were investigated, and it was found that they exhibited excellent dielectric strength.
CERAMICS INTERNATIONAL
(2022)
Article
Chemistry, Physical
Shuohua Zhang, Xiaoguang Guo, Song Yuan, Zhuji Jin, William C. Tang
Summary: A new nanoindentation algorithm was developed to study the structural evolution in glass-ceramics, revealing the changes in point defects between different crystalline phases and the impact of irreversible supersaturated bonds in GCP on defect healing. This study provides insight into the behaviors of two-phase heterogeneous materials at the nanoscale.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Coatings & Films
K. Bobzin, C. Kalscheuer, M. Carlet, S. Schmauder, V. Guski, W. Verestek, M. Tayyab
Summary: In this study, a machine learning algorithm was used to characterize the microstructure of a hard coating, and material model parameters for the coating, interlayer, and substrate were determined by fitting simulated force-displacement curves to experimental ones. The developed model can effectively simulate and validate the deformation behavior of a CrAlN coating during nanoindentation at different indentation loads.
SURFACE & COATINGS TECHNOLOGY
(2023)
Article
Materials Science, Composites
Shaik Mubina, P. Sudharshan Phani, Asit Kumar Khanra, Bhaskar Prasad Saha
Summary: An advanced high-speed nanoindentation technique was employed to analyze the combined reinforcing effect of carbon fibers in the SiC matrix. Various types of composite tubes were produced by introducing different forms of carbon fibers and composite powders, and the properties of the tubes were evaluated using traditional processes as well as nanoindentation techniques.
COMPOSITE INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Geethasree Kommineni, Alam Md Zafir, P. Sudarshan Phani, Rajdeep Sarkar, V. V. Satya Prasad, Brahma Raju Golla
Summary: The addition of Ti and Zr alloying elements resulted in the formation of equilibrium alpha-Nb5Si3 phase in situ, improving the properties of the alloys and being cost effective. The volume fraction of the Nb-ss phase increased with the addition of elements, with hardness increasing with Ti and decreasing with Zr.
MATERIALS CHARACTERIZATION
(2021)
Article
Materials Science, Multidisciplinary
E. M. Rossi, P. Sudharshan Phani, R. Guillemet, Julie Cholet, Doriane Jussey, W. C. Oliver, M. Sebastiani
Summary: The novel nanoindentation based method presented in this work is able to measure the pull-off adhesive forces covering hydrophilic to super-hydrophobic surfaces, with potential applications in fast non-destructive mapping of SFE over heterogeneous surfaces. The method's limitations and shortcomings in reliability and reproducibility of results are critically discussed, focusing on experimental issues that could affect the measurements.
JOURNAL OF MATERIALS RESEARCH
(2021)
Article
Materials Science, Multidisciplinary
P. Sudharshan Phani, W. C. Oliver, G. M. Pharr
Summary: The method for measuring hardness and elastic modulus of small volumes of material through instrumented indentation was initially developed by Oliver and Pharr in their early works. This has led to advancements in the field of small scale nanomechanical testing, with improvements in measurement electronics allowing testing under a wider range of conditions. The article provides an updated overview of factors affecting precision and accuracy of nanoindentation test results, focusing on the continuous stiffness measurement technique (CSM) and presenting a step-by-step procedure for conducting CSM based tests, along with calibration procedures for optimal precision and accuracy. Additionally, an assessment and comparison of different testing procedures is presented.
JOURNAL OF MATERIALS RESEARCH
(2021)
Article
Nanoscience & Nanotechnology
S. Janakiram, P. Sudharshan Phani, Govind Ummethala, Sairam K. Malladi, J. Gautam, Leo A. Kestens
Summary: This study investigates the structure-property correlations at the micrometer length scale during recovery and early recrystallization of a cold rolled high strength steel composed of ferrite and pearlite. High resolution nano-indention mapping technique and electron microscopy were used to study the local microstructure and hardness variations with annealing temperature. A clustering algorithm was employed to determine the properties of the constituent microstructural features.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Fereshteh Mallakpour, Masoud Kasraie, Erik G. Herbert, P. Sudharshan Phani, Stephen A. Hackney
Summary: Nanoindentation and electron microscopy were used to study the length-scale-dependent stress relaxation mechanisms in well-annealed, high-purity indium. The experiments identified two distinct surface morphologies of residual hardness impressions, indicating different deformation mechanisms. The formation and growth of metallic dendrites were explained by the stress relaxation mechanisms at the buried interface between metallic anode and solid electrolyte separator.
JOURNAL OF MATERIALS RESEARCH
(2021)
Article
Materials Science, Multidisciplinary
P. Sudharshan Phani, W. C. Oliver, G. M. Pharr
Summary: Accurately determining the applied load is crucial in measuring hardness, especially in nanoindentation testing with continuous stiffness measurement (CSM). This study proposes the concept of an effective load during nanoindentation creep testing with CSM and validates it through theoretical analysis and experiments, finding significant implications for rate-dependent materials.
JOURNAL OF MATERIALS RESEARCH
(2021)
Article
Nanoscience & Nanotechnology
Deekshith G. Kalali, Sairam Antharam, Mohsin Hasan, P. Sai Karthik, P. Sudharshan Phani, K. Bhanu Sankara Rao, Koteswararao Rajulapati
Summary: The remarkably high hardness in the alloy, achieved through careful microstructural engineering and optimal addition of alloying elements, suggests potential for developing novel structural materials based on a multi-principal element approach.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Naveen Manhar Chavan, P. Sudharshan Phani, M. Ramakrishna, L. Venkatesh, Prita Pant, G. Sundararajan
Summary: Cold spray deposition involves unique combination of high strain rate and moderate to high strain deformation, leading to significant grain refinement and deformation twinning in Cu and Cu-Al alloys. Experimental observations align well with theoretical predictions, showing significant heterogeneity in cold spray coatings and identifying factors influencing hardness. Twin mediated deformation mechanism is found to explain the lower boundary strengthening in presence of fine twins.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Kali Prasad, Vikram Balaji, Hariharan Krishnaswamy, P. Sudharshan Phani, Pierpaolo Carlone
Summary: This study demonstrates that the value of strain rate sensitivity estimated from stress relaxation tests is inaccurate and proposes a new method for accurately determining this value.
MECHANICS OF MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
P. Sudharshan Phani, B. L. Hackett, C. C. Walker, W. C. Oliver, G. M. Pharr
Summary: This study proposes an analytical framework to guide high strain rate hardness measurements through nanoindentation testing. The research results demonstrate the wide potential applications of nanomechanical measurements with low noise, fast time constants, and high data acquisition rates.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Physics, Applied
L. A. Boatner, C. B. Finch, W. E. Brundage, J. A. Kolopus, G. R. Gruzalski, K. E. Johanns, P. Sudharshan Phani, G. M. Pharr, W. C. Oliver
Summary: Instrumented indentation experiments at elevated temperatures require careful attention to experimental details, including the choice of indenter tip material. This study used rf-induction heating float-zone and high-temperature solution single-crystal growth techniques to prepare a suite of bulk refractory carbide specimens. These materials were characterized and compared to sapphire and polycrystalline WC-Co, and the results showed that single-crystal WC is a promising candidate for elevated-temperature nanoindentation tips.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Harita Seekala, Lavakumar Bathini, Nitin P. P. Wasekar, Hariharan Krishnaswamy, P. Sudharshan Phani
Summary: The seminal work of Nix and Gao laid the foundation for quantifying the indentation size effect (ISE). This study presents a unified approach to quantify ISE by considering the effects of materials, geometry, and other coupled parameters. Experimental studies on pulsed electro-deposited nickel validate the model predictions for the depth dependence of hardness. Factors such as grain size, dislocation density, tip geometry, constraint factors, and plastic zone size are found to affect ISE.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Nanoscience & Nanotechnology
Chetan Singh, Hariharan Krishnaswamy, Sudarshan Phani Pardhasaradhi, Fu Chian Chen, Dinh-Phuc Tran, Chih Chen, Jayant Jain
Summary: Depth sensing nanoindentation experiments were conducted to investigate the strain rate dependentindependent behaviors of nanotwinned microcrystalline Cu. Different additives were used for electro-deposition to control microstructural parameters, such as grain size and twin spacing. The sample with the lowest twin lamella spacing exhibited a lower stress exponent, potentially leading to enhanced ductility. The mechanical properties obtained by introducing nanotwins in coarser initial grain size are comparable to nanotwinned nanocrystalline materials, suggesting a new paradigm for a broader range of nanotwinned materials.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Mechanical
Aditya Prakash, Tawqeer Nasir Tak, Namit N. Pai, Harita Seekala, S. V. S. Narayana Murty, P. S. Phani, Sivasambu Mahesh, P. J. Guruprasad, Indradev Samajdar
Summary: Macroscopic shear bands (MSB) may form during hot working of metallic materials. The microstructural transitions between the onset of flow instability and MSB inception are not fully understood. In this study, aluminum alloy specimens were tested at different temperatures and it was found that MSB only appeared at a certain level of deformation. The formation of MSB was explained by the development of clusters of severely deforming grains and the differential dynamic recovery between hard- and soft-oriented grains.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)