Nanomechanical Behavior Research Articles

Effect of cellulose nanofiber addition on the microstructure characterization and nano-mechanical behavior of interfacial transition zones in recycled concrete

Effect of cellulose nanofiber addition on the microstructure characterization and nano-mechanical behavior of interfacial transition zones in recycled concrete

Influence of Friction Stir Spot Processing on Grain Structure Evolution and Nanomechanical Behavior of Cold-Sprayed Al Coating on Ti Substrate

Influence of Friction Stir Spot Processing on Grain Structure Evolution and Nanomechanical Behavior of Cold-Sprayed Al Coating on Ti Substrate

Microstructural and nanomechanical behavior of friction stir welded dissimilar joint of AA2219-T6/AA2195-T8 alloys

Microstructural and nanomechanical behavior of friction stir welded dissimilar joint of AA2219-T6/AA2195-T8 alloys

Influence of topography on nano-mechanical properties of cylindrical magnetron sputtered TiN films

Numerous studies on Nano-mechanical behavior of the thin films explained primarily in terms of their film morphology and particle size rather than film topography. Therefore, the current study investigates the effect of film topography on the nano-mechanical characteristics of the film. Ti/TiN multilayer thin films were deposited at varying deposition pressures by using an indigenously developed Cylindrical Magnetron Sputtering (CMS) unit. Surface crystallographic information is characterized by synchrotron-based Grazing Incidence XRD analysis. Film growth follows self-assembled nano hill architecture as revealed by AFM and in situ Scanning Probe Microscopy images. The tribo-mechanical properties of the film is dependent on the height and spacing of its self-assembled structure, which experiences either crushing or buckling under the indenter load, thereby affecting film characteristics. Film deposited at moderate pressure exhibits superior wear behavior, attributed to the interplay between Plasticity Index (PI) and Depth Recovery Ratio (DRR). The study primarily focused on film growth phenomena by using cylindrical targets and their influence on nanomechanical properties of the film.

Understanding heterogeneity and anisotropy of Duplex Stainless Steel's elastic/plastic nature through property mapping technique

Accelerated property mapping, an advanced indentation technique was used to describe the nanomechanical behaviour of duplex stainless steel (DSS) surfaces prior to and post heat treatments. Heterogeneity in deformation responses and relative elastic and/or plastic nature of DSS was assessed on longitudinal and transverse directions through load–displacement curves, property maps, histograms of hardness (H), modulus (E) and indentation works. Empirical ratios such as H/E, (H/E)1/2, H3/E2 and plasticity index were employed to understand the anisotropy across the directions.

Nanomechanical characterization of BiFeO3 ferroelectric ceramics

Ferroelectric perovskites are pivotal in diverse technological applications; however, a gap persists in our comprehension of their mechanical properties, emphasizing the need for additional exploration. In the present study, we report on the nanomechanical behavior of BiFeO3 ceramics in the force range between 200 μN and 2 mN, including the evolution of the hardness and the reduced Young’s modulus from (9.9 ± 0.4) GPa and (113.7 ± 6.9) GPa, respectively, with increasing force. A sequence of plastic-deformation mechanisms under the cube-corner probe was revealed through a first pop-in analysis in combination with a variety of electron microscopy techniques, starting with a homogeneous dislocation nucleation, multiplication and rearrangement leading to sub-grain formation, a phenomenon observed in metals but not in ceramics.

Beyond nothingness in the formation and functional relevance of voids in polymer films

Voids—the nothingness—broadly exist within nanomaterials and impact properties ranging from catalysis to mechanical response. However, understanding nanovoids is challenging due to lack of imaging methods with the needed penetration depth and spatial resolution. Here, we integrate electron tomography, morphometry, graph theory and coarse-grained molecular dynamics simulation to study the formation of interconnected nanovoids in polymer films and their impacts on permeance and nanomechanical behaviour. Using polyamide membranes for molecular separation as a representative system, three-dimensional electron tomography at nanometre resolution reveals nanovoid formation from coalescence of oligomers, supported by coarse-grained molecular dynamics simulations. Void analysis provides otherwise inaccessible inputs for accurate fittings of methanol permeance for polyamide membranes. Three-dimensional structural graphs accounting for the tortuous nanovoids within, measure higher apparent moduli with polyamide membranes of higher graph rigidity. Our study elucidates the significance of nanovoids beyond the nothingness, impacting the synthesis‒morphology‒function relationships of complex nanomaterials.

Microstructure Evolution and Nanomechanical Behavior of Micro-Area in Molten Pool of Selective Laser Melting (CoCrNi)82Al9Ti9 High-Entropy Alloy

Microstructure Evolution and Nanomechanical Behavior of Micro-Area in Molten Pool of Selective Laser Melting (CoCrNi)82Al9Ti9 High-Entropy Alloy

Nanomechanical behavior, adhesion and wear resistance of tin oxide coatings for biomedical applications

AbstractThis study investigates the properties of tin oxide coatings employed in biomedical applications. The films were deposited on a clean glass substrate, preheated at 450 °C, applying the spray pyrolysis technique as the latter produces crystallized thin films without the need for further heat treatment. X‐ray diffraction analysis showed that tin oxide films had a tetragonal structure characterized by a preferential orientation (111). The measurements of reflectance and transmittance revealed a wide optical band gap of 4.0 eV. Nanoindentation tests showed that the tin oxide coating, with a hardness of 5.9 GPa and a Young's modulus of 78 GPa, exhibited elastic‐plastic behavior. In addition, tribological tests indicated that tin oxide coating had a very low coefficient of friction (μ=0.06), high wear resistance (wear rate 2.10−5 mm3 N−1 m−1) and good adhesion to the substrate (critical adhesion load of 5.55 N). It was also noticed that tin oxide thin films had antibacterial activity due to their nanocrystalline impurities. These properties make tin oxide perfectly acceptable for biomedical applications.

Nanomechanical behavior of coal with heterogeneous minerals and pores using nanoindentation.

The coal's mechanical properties have a significant influence on mining safety and the mine environment. Preparing a standard sample and conducting repeat mechanical testing are challenging because the coal is primarily soft, fragmented, and rich in developed fractures. This study used nanoindentation technology, combined with X-ray diffraction, small-angle X-ray, a high magnification microscope, and mechanical parameter scale-up analysis, to study the micromechanical of three coals being dominated by heterogeneous components and pores. The results show that load-displacement curves with different maximum loads (50 mN, 100 mN, and 200 mN) all appear the pop-in events, and coal heterogeneity affects the frequency of their occurrence. As the maximum load is increased, pop-in event of DSC appears once each, YW increases from zero to three times and HM decreases from four to two times. The heterogeneity of pore structure has little effect on residual displacement, which is mainly affected by hard minerals, and hard minerals reduce the law that residual displacement increases with the increase in maximum load. The micromechanical parameters of soft coals are mainly affected by large pores, while hard coals are mainly affected by hard minerals. The coal's heterogeneity does not affect the linear relationship between hardness and elastic modulus, but stronger heterogeneity will weaken the linear relationship between fracture toughness and elastic modulus. Compared to the mechanical parameters after scale-up, the values obtained based on nanoindentation are less than 15.588% larger, and the increase in the heterogeneity and hard minerals can make the predicted parameters more accurate. The nanoindentation technique can not only provide an efficient and accurate method for studying the mechanical properties of heterogeneous coal at the nanoscale, an important guide for large-scale coal.

An experimental investigation on nanomechanical and nanotribological behavior of tantalum nitride coating deposited on Ti6Al7Nb alloy

In this investigation, TaN coating was deposited on ASTM-F1295 grade Ti6Al7Nb alloy by radio frequency magnetron sputtering. Structural, surface morphological, and compositional analyses were conducted using Grazing Incidence-XRD, FESEM, EDS and XPS. The results affirmed that uniform and sub-stoichiometric TaN coating was deposited with the polycrystalline nature of TaN, exhibiting a cubic-NaCl-like structure. Nanoindentation tests revealed that the hardness and modulus of TaN coating decrease with increasing indentation load. Moreover, scratch test under progressive loading conditions uncovered critical loads corresponding to cohesion and adhesion failures. Nanotribological tests were conducted on deposited TaN against different counter bodies (steel and ceramic ball) disclosed fine abrasive grooves on the coating and demonstrate anti-wear properties.

Mechanical and Tribological Performance of AlCrFeCuNi-(Vx) HEAs Synthesized via Arc Melting technique

The AlCrFeCuNi-(Vx) High Entropy Alloy (HEA) was created via arc-melting and casting processes. The influence of vanadium (V) on the Nano mechanical behaviour, microstructural development, as well as the wear performance of the produced HEAs was examined. Notable improvements to the Nano hardness of the HEAs were evident with an increase in V content from 1at% to 5at%. The addition of V altered the frictional behaviour of the HEA with an increased coefficient of friction as V is increased. The addition of V also greatly affected the microstructural orientation of the HEA, exhibiting signs of homogenization as V content increased.

Fabrication and Characterization of AlCrFeCuNi High Entropy Alloy doped with (Yx) via Arc Melting Technology for Engineering Application

AlCrFeCuNi high entropy alloy (HEA) was fabricated using an arc-melting and casting process. Furthermore the alloy’s characteristics were adjusted through the addition of Yttrium (Y) alloying additives at 1wt%, 3wt%, and 5wt%. The effect of Y at varied atomic ratios on the microstructural evolution and Nano-mechanical behavior of the synthesized HEAs was investigated. The HEA being studied proved to possess superior mechanical properties as compared to Ti64, Ni-based alloys and stainless-steel materials. The hardness and Young’s modulus were the HEAs’ mechanical properties investigated. The results show that Y incorporation in the AlCrFeCuNi HEA matrix resulted in the increase in microhardness. This was because the presence of Y caused grain refinement and increases the probability of precipitates or second phases forming inside the alloy. It was also observed that the elastic modulus increased with the addition of Y. This was because elastic modulus, which is a measure of a material's stiffness, also tends to increase with grain refinement.

Nanomechanical Behavior of Pentagraphyne-Based Single-Layer and Nanotubes through Reactive Classical Molecular Dynamics

A novel 2D carbon allotrope, pentagraphyne (PG-yne), was introduced in a recent theoretical study. This unique structure is derived from pentagraphene by incorporating acetylenic linkages between sp3 and sp2 hybridized carbon atoms. Given its intriguing electronic and structural properties, it is imperative to investigate the mechanical characteristics and thermal responses of PG-yne in both monolayer and nanotube configurations, which encompass different chiralities and diameters. We conducted fully atomistic reactive molecular dynamics (MD) simulations employing the ReaxFF potential to address these aspects. Our findings reveal that Young’s modulus of PG-yne monolayers stands at approximately 51 GPa at room temperature. In contrast, for the studied nanotubes, regardless of their chirality, it hovers around 45 GPa. Furthermore, our observations indicate that PG-yne-based systems feature an extensive and relatively flat plastic region before reaching the point of total fracture, irrespective of their topology. Regarding their thermal properties, we identified a melting point at approximately 3600 K, accompanied by a phase transition around 1100 K.

Cinematographic study ofstochastic chemical events at atomic resolution.

The advent of single-molecule atomic-resolution time-resolved electron microscopy (SMART-EM) has created a new field of 'cinematic chemistry,' allowing for the cinematographic recording of dynamic behaviors of organic and inorganic molecules and their assembly. However, the limited electron dose per frame of video images presents a major challenge in SMART-EM. Recent advances in direct electron counting cameras and techniques to enhance image quality through the implementation of a denoising algorithm have enabled the tracking of stochastic molecular motions and chemical reactions with sub-millisecond temporal resolution and sub-angstrom localization precision. This review showcases the development of dynamic molecular imaging using the SMART-EM technique, highlighting insights into nanomechanical behavior during molecular shuttle motion, pathways of multistep chemical reactions, and elucidation of crystallization processes at the atomic level.

Effect of graphene on the surface nanomechanical behavior and subsurface layer of GaN damage during nanogrinding using molecular dynamics simulation

Molecular dynamics simulations were used to investigate the surface nanomechanical behavior and subsurface layer damage of gallium nitride (GaN)/graphene composites when subjected to nanogrinding with diamond abrasive. The effects of graphene on GaN were analyzed based on parameters such as atomic displacement, forces, crystal structure, subsurface damage, atomic stress, and temperature. The simulation results indicate that graphene has a noteworthy impact on the surface morphology, such as the pile-up atoms on the workpiece surface and the elastic recovery on the machined surface. In addition, the addition of graphene can reduce the atomic temperature, stress, and normal and tangential forces. In terms of subsurface damage formation, graphene can suppress lattice damage and amorphization of GaN during nanogrinding. The addition of graphene can significantly reduce the dislocation length and the phase transition from wurtzite to a five-fold coordination hexagonal structure. Overall, the addition of graphene can improve the deformation mechanism on the GaN surfaces. This study provides technical references for the design of GaN with improved friction and wear resistance.

Nanomechanical properties of Al-Tb marginal metallic glass

Al-Rare Earth (RE) metallic glasses provide an effective model system to study the effect of nanocrystallites in an amorphous matrix on nanomechanical behavior. In this work, we achieved a series of Al-Tb metallic glass-crystalline composites with systematically varying crystalline content through annealing. The nanomechanical properties were characterized using micropillar compression tests and nanoindentation for as-quenched amorphous and annealed amorphous/nanocrystalline composite specimens. The promising hardness increases after annealing from 3.0 GPa to 4.6 GPa and elastic modulus increment from 68 GPa to 92 GPa were discussed in detail, considering the structural features of Al-RE marginal metallic glass formers. The increase in elastic modulus is associated with the nucleated fcc-Al nanocrystals that divide the amorphous matrix, leading to the branching of the shear bands. The correlation between the fcc-Al nanocrystals and the behavior of shear bands was discussed in detail.

Insights into nano-mechanical degradation behavior of Ag/Ti2AlC composite under different arc erosion stages

Serious arc erosion is the main reason for premature failure of the Ag-matrix composite electrical contact materials in actual service. Clarifying the structure and property degradation process is crucial for creating eco-friendly Ag/MAX electrical contacts and upgrading high-performance materials for low-voltage switch applications. In this study, the representative Ag/Ti2AlC electrical contacts were designed into three arc erosion stages (from 1 to 5610 cycles) by ex-situ arc discharging experiment, and the nanoindentation technique was then applied to in-depth analyze the evolution behavior of nano-mechanical properties by comparing nano hardness, modulus, creep, continuous stiffness, elastic/plastic deformation, and NanoBlitz 3D Mapping indentation results in different erosion stages. Finally, the inherent relationship among the structural dissociation of Ti2AlC, and compositional changes of Ag/Ti2AlC interface and nano-mechanical properties of composite was revealed, and the material degradation model and anti-arc erosion mechanism were proposed. This work further elucidates the intrinsic source of excellent arc erosion resistance and degradation process of Ag/Ti2AlC composite from the nano-mechanical perspective and lays a theoretical foundation for the future design and optimization of this material system.

Insights into nanomechanical behavior of B. mori silk fibroin-hydroxyapatite bio-nanocomposite using MD simulations: Role of varying hydroxyapatite content

Nanocomposite material composed of Bombyx mori Silk Fibroin and hydroxyapatite (B. mori SF-HA) is a potential biomaterial for bone tissue engineering. Here, Bombyx mori Silk Fibroin (B. mori SF) is a flexible and tough organic, polymer phase, and hydroxyapatite (HA) is hard and stiff mineral phase. Knowledge about mechanical deformation behavior together with governing mechanisms, and the role of the two phases (SF and HA phase) and interfacial interactions between them, in B. mori SF-HA biomaterial, at fundamental level is an important factor to consider while developing the tissue grafts. Such nanometer scale behavior is often preferably investigated using molecular dynamics method. Present study aims at understanding the mechanical deformation behavior and associated physical mechanisms in B. mori SF-HA bio-nanocomposite, at nanoscale. For this purpose, computational atomistic models of B. mori SF-HA bio-nanocomposite are developed with varying HA content. Mechanical behavior analysis of these composite models under tensile loading were performed using Molecular Dynamics (MD) simulations. Elastic modulus and tensile strength values in the range of 7–20 GPa and 200–700 MPa, respectively, are obtained for B. mori SF-HA composite, in case of different HA contents, wherein, increased mechanical properties are observed with increase in HA content. Analyses of the deformation trajectories show that the deformation flow behavior in B. mori SF-HA bio-nanocomposites is mainly defined by the soft SF phase. However, energetics analyses show that, the HA phase and SF-HA interfacial interactions also play a considerable role in mechanical performance of B. mori SF-HA bio-nanocomposite. Additionally, interfacial shear strength values in B. mori SF-HA bio-nanocomposite, for different HA contents, have also been obtained. The observations made and insights gained in present work has contribution and impact in gaining an insight into the mechanistic interactions occurring at nanoscale between SF and HA phases in B. mori SF-HA bio-composite.

Nanomechanical behavior of polystyrene/graphene oxide nanocomposites

The in-situ investigation of the nanomechanical features of the polymer graphene nanocomposites has become a challenging and an indispensable task to achieve the required application. Graphene oxide (GO) nanocomposites were prepared at 1.0% weight fraction of GO to reinforce polystyrene (PS) using solution blending approach. The morphology of the resulting nanocomposites was characterized by optical, scanning electron, transmission electron, atomic force, and scattering scanning near-field optical microscopies. These showed a uniform dispersion of graphene oxide nano-sheets in the PS matrix. By adopting Derjaguin–Muller–Toporov (DMT) formula, the nanomechanical properties for the cryogenically fractured surface of the composites were characterized using the traditional atomic force microscopy (AFM), peak-force quantitative nanomechanical mapping (QNM), and tip-force mode functioned with scattering scanning near–field optical microscopy (s-SNOM). Young’s modulus of the PS matrix varied around (1–2) GPa as shown by QNM and s-SNOM similar to what was reported in the literature. However, while putative GO nano-sheets were measured to have a higher elastic modulus than the surrounding matrix in Peak-Force QNM experiments, they were significantly below literature values. By using Tip-Force mode related to s-SNOM, the expected values of Young’s modulus for GO were recovered.