Edge Dislocations Research Articles

Functional Medium Entropy Alloys for Joint Replacement: An Atomistic Perspective of Material Deformation and a Correlation to Wear, Corrosion, and Biocompatibility

The present study adopts a muti-facet approach to design bio inspired concentrated alloys for potential application as articulating surfaces in joint replacements. A series of equiatomic, Nb rich and Ti rich TiMoNbZr based medium entropy alloys (MEAs) were processed via arc melting and their mechanical, in-vitro corrosion, wear, and in vitro and in vivo biocompatibility were investigated. Equiatomic MEA had primarily bcc with minor hcp phases where the single bcc was achieved with the addition of Nb. The single bcc Nb rich alloy resulted in 13% elongation, much higher than equiatomic or Ti rich alloy. All the MEAs showed comparatively higher yield strength due to the climb of edge dislocations which is the main rate limiting mechanism at 300 K, as evident molecular dynamics (MD) simulation. The locally fluctuating energy landscape promotes kinks on edge dislocation, and at local minima nanoscale segments gets pinned. Upon yielding the entangled kink leaves a trail of vacancies/interstitials and escapes via climb motion to render high yield strength. The higher corrosion and pitting resistance of Nb enriched alloys can be attributed to the stable ZrO2, Nb2O5, TiO2, and MoO3 oxides, high polarization resistance (106-105 Ωcm−2), and low defect densities (1016-1018). In vitro cell-materials interaction using MC3T3-E1 showed bioinert but cytocompatible nature of the MEAs. The wear rate of the MEAs was in the range of 7-9×10−5 mm3N−1m−1. The wear debris did not show any tissue necrosis when implanted in rabbit femur rather new bone regeneration can be seen around the particles. Statement of SignificanceIn the present work, a noble Nb enriched MEAs with superior mechanical, in vitro wear, corrosion and cytocompatibility properties was designed for articulating surfaces in joint replacement.•Single bcc in Nb enriched MEAs resulted in 13 % elongation with high hardness and yield strength.•Climb of entangled edge segment is the rate limiting mechanism in controlling high yield strength of MEAs at 300 K.•High polarization resistance (106-105 Ωcm−2), and low defect densities (1016-1018) attributes to ZrO2, Nb2O5, TiO2, and MoO3 oxides enriched passive film.•Wet sliding wear rate ranged in order 7-9×10−5 mm3N−1m−1. In-situ generated wear debris when implanted in rabbit femur did not show any tissue necrosis rather new bone regeneration was observed around debris.

Mobility of dislocations in carbon nanotube bundles

Horizontally aligned carbon nanotubes (CNTs) have a unique combination of mechanical and physical properties and find numerous applications. The shear deformation of a horizontally aligned CNT bundle is studied under plane-strain conditions using the method of molecular dynamics. The CNTs in the bundle are not perfectly packed, and it is important to see how defects alter the mechanisms of their deformation under applied load. The defects in the form of edge dislocations are introduced into the bundle. It is found that the dislocation core structure depends on the CNT diameter, as the deformability of the CNT cross section increases with the diameter. Different deformation mechanisms (dislocation sliding or cracking) are revealed in the bundles with CNTs of different diameters. The results presented describe how the dislocation core structure affects the dislocation mobility in CNT bundles and the mechanisms of their deformation.

Study on the mechanism of rapid densification and structural evolution of C/C composites by cooling pyrolysis

A large thermal gradient about 190 ℃/cm was established in the thickness direction of preform and the cylindrical carbon/carbon composites with radial gradient pyrocarbon (PyC) distribution were rapidly prepared via the cooling pyrolysis technology in the high temperature surface based on the large thermal gradient chemical vapor infiltration (CPTHTS-LTGCVI). The decrease of initial temperature and the increase of cooling rate both contribute to the opening of closed pore and pore expansion, which are conducive to improving the densification degree. Moderate initial temperature (about 1130℃) and cooling rate (10 ℃/5 h) are optimal to rapidly preparing C/C composites with good density uniformity. For the whole cylindrical C/C composites, the faster the cooling rate, the higher the density and density uniformity, the fewer the super macropores. As the cooling rate is 10 ℃/2.5 h, the density of sample can reach 1.57 g/cm3 within 50 h, and the carbon yield in the first stage and accumulation can reach 84 % and 50 %, respectively. From the inner wall (IW) to the outer wall (OW), there are three successive regions about RL, RL+SL and SL PyC with gradually weakened texture, which is related to the insufficient pyrolysis caused by the decreased temperature and increased concentration, and the aromatization caused by the extended gas retention time. The edge dislocations and non-coherent sub-grain boundaries of PyC may be related to the distorted aromatic carbon planes containing five-membered rings. The edge dislocations may be the main reason of texture reduction and structural evolution of PyC.

Higher Order Topological Defects in a Moiré Lattice

AbstractTopological defects are ubiquitous, they manifest in a wide variety of systems such as liquid crystals, magnets or superconductors. The recent quest for non‐abelian anyons in condensed matter physics stimulates the interest for topological defects since they can be hosted in vortices in quantum magnets or topological superconductors. In addition to these vortex defects, this study proposes to investigate edge dislocations in 2D magnets as new building blocks for topological physics since they can be described as vortices in the structural phase field. It demonstrates the existence of higher order topological dislocations within the higher order moiré pattern of the van der Waals 2D magnet CrCl3 deposited on Au(111). Surprisingly, these higher order dislocations arise from ordinary simple edge dislocations in the atomic lattice of CrCl3. This study provide a theoretical framework explaining the higher order dislocations as vortices with a winding Chern number of 2. It is expected that these original defects can stabilize some anyons either in a 2D quantum magnet or within a 2D superconductor coupled to it.

Effect of vacuum diffusion bonding on the mechanical and conductive properties of bonded bulk copper single crystals

Recrystallization-free atomic-level (AL) bonding between bulk copper single crystals was achieved by combining chemical mechanical polishing (CMP) and vacuum diffusion bonding. Under various bonding conditions, the bonded copper specimens can be classified into three categories: AL-bonded, HH-bonded, and L-bonded specimens. AL-bonded copper single crystals were obtained by performing bonding under 20 MPa at 600 °C for 60 min, achieving the mechanical and electrical properties that are closest to those of the parent copper single crystal. The AL-bonded interface is characterized by an asymmetrically tilted sub-grain boundary with a 2° misorientation and consists of two sets of edge dislocations with mutually perpendicular Burgers vectors. The formation of the AL-bonded interface depends on two critical factors: the creation of ultra-flat bonded surfaces and performing diffusion bonding within the elastic deformation range. Achieving an ultra-flat surface that eliminates residual stress allows for bonding under relatively low pressure. With a moderate bonding temperature and holding time, it is possible to simultaneously avoid the formation of voids and recrystallizations at the bonding interface, thereby achieving a high-quality AL-bonded interface between bulk copper single crystals.

Dislocation structures in micron-sized Ni single crystals produced via tension–compression cyclic loading

The strength and deformation characteristics of micron-sized metals under monotonic loading have long been investigated. In contrast, despite its practical significance, their fatigue behavior remains unexplored. To this end, tension–compression fatigue tests were conducted herein on micron-sized Ni single crystals to elucidate their fatigue behavior and internal dislocation structures. Specimens with square cross sections of 5 and 2 μm on a side were prepared and subjected to cyclic loading at low stress amplitudes, which did not induce fatigue cracking in bulk metals. Remarkably, fatigue cracks were not present in 5-μm-wide specimens, whereas intrusions/extrusions were observed in 2-μm-wide specimens, leading to crack initiation. Vein-like structures comprising edge dislocations were observed in 5-μm-wide specimens, which are commonly observed in bulk metals. Conversely, the dislocation structure in 2-μm-wide specimens resembled that associated with persistent slip bands, which cause intrusions/extrusions and fatigue cracking in bulk metals under high stress amplitudes. The experimental findings indicate that the fatigue behavior of small-sized metal single crystals is characterized by the absence of vein formation.

Void and helium bubble interactions with dislocations in an FCC stainless steel alloy: anomalous hardening and cavity cross-slip locking

The critical stress for cutting of a void and He bubble (generically referred to as a cavity) by edge and screw dislocations has been determined for FCC Fe0.70Cr0.20Ni0.10—close to 300-series stainless steel—over a range of cavity spacings, diameters, pressures, and glide plane positions. The results exhibit anomalous trends with spacing, diameter, and pressure when compared with classical theories for obstacle hardening. These anomalies are attributed to elastic anisotropy and the wide extended dislocation core in low stacking fault energy metals, indicating that caution must be exercised when using perfect dislocations in isotropic solids to study void and bubble hardening. In many simulations with screw dislocations, cross-slip was observed at the void/bubble surface, leading to an additional contribution to strengthening. We refer to this phenomenon as cavity cross-slip locking, and argue that it may be an important contributor to void and bubble hardening.

Mechanisms and kinetics of prismatic dislocation loop removal during graphitization

Molecular dynamics simulations are used to study the structure and removal of prismatic dislocation loops during graphitization. The carbon models contain a mixture of screw and edge dislocations, and are created by self-assembly at high temperature. Four mesh-based analysis tools are used to track the time-evolution of the dislocation loops, providing insight into loop structure and allowing quantification of kinetics. We find that the loop structure is complex, being dispersed in three dimensions with alternating screw and edge components in multiple slip planes. Loop removal involves edge glide through kink formation and propagation, followed by a slower screw glide mechanism. All analysis tools yield similar activation energies, in the range of 2.9 ± 0.3 eV, consistent with recent experimental work by ourselves. Literature values for the kinetics of graphitization fall into two brackets, a lower range of 2.8–3.9 eV, and a higher range of 7.8–11.6 eV. This work supports the lower range and suggests that prismatic dislocation loops are the key defect removed during graphitization.

Dislocation pinning in helium-implanted tungsten: A molecular dynamics study

Using molecular dynamics simulations, we investigate the interaction of edge dislocations with He-filled Frenkel pairs (He2V-SIA), the predominant defect type in helium-implanted tungsten. Clusters of 3–10 He2V-SIA are seen to be stable with their pinning strength increasing with size. For all cluster sizes, the dislocation bows around the cluster and unpins while carrying SIAs with it. The helium-vacancy complex and new vacancies left behind, have little pinning effect, explaining the “defect-clearing” and experimentally observed deformation softening. The predicted solute hardening for 3000 appm helium-induced defect distribution of varying sizes, is in excellent agreement with previous experimental observations.

Redox Promoted Rapid and Deep Reconstruction of Defect-Rich Nickel Precatalysts for Efficient Water Oxidation.

Understanding the reconstruction mechanism to rationally design cost-effective electrocatalysts for oxygen evolution reaction (OER) is still challenging. Herein, a defect-rich NiMoO4 precatalyst is used to explore its OER activity and reconstruction mechanism. In situ generated oxygen vacancies, distorted lattices, and edge dislocations expedite the deep reconstruction of NiMoO4 to form polycrystalline Ni (oxy)hydroxides for alkaline oxygen evolution. It only needs ≈230 and ≈285mV to reach 10 and 100mA cm-2, respectively. The reconstruction boosted by the redox of Ni is confirmed experimentally by sectionalized cyclic voltammetry activations at different specified potential ranges combined with ex situ characterization techniques. Subsequently, the reconstruction route is presented based on the acid-base electronic theory. Accordingly, the dominant contribution of the adsorbate evolution mechanism to reconstruction during oxygen evolution is revealed. This work develops a novel route to synthesize defect-rich materials and provides new tactics to investigate the reconstruction.

Spatiotemporal optical vortices with controllable radial and azimuthal quantum numbers

Optical spatiotemporal vortices with transverse photon orbital angular momentum (OAM) have recently become a focal point of research. In this work we theoretically and experimentally investigate optical spatiotemporal vortices with radial and azimuthal quantum numbers, known as spatiotemporal Laguerre-Gaussian (STLG) wavepackets. These 3D wavepackets exhibit phase singularities and cylinder-shaped edge dislocations, resulting in a multi-ring topology in its spatiotemporal profile. Unlike conventional ST optical vortices, STLG wavepackets with non-zero p\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{{\\boldsymbol{p}}}}}}$$\\end{document} and l\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{{\\boldsymbol{l}}}}}}$$\\end{document} values carry a composite transverse OAM consisting of two directionally opposite components. We further demonstrate mode conversion between an STLG wavepacket and an ST Hermite-Gaussian (STHG) wavepacket through the application of strong spatiotemporal astigmatism. The converted STHG wavepacket is de-coupled in intensity in space-time domain that can be utilized to implement the efficient and accurate recognition of ultrafast STLG wavepackets carried various p\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{{\\boldsymbol{p}}}}}}$$\\end{document} and l.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{{\\boldsymbol{l}}}}}}.$$\\end{document} This study may offer new insights into high-dimensional quantum information, photonic topology, and nonlinear optics, while promising potential applications in other wave phenomena such as acoustics and electron waves.

Effect of sintering temperature on microstructure and mechanical properties of MoNbVTa0.5Cr high-entropy alloys fabricated by powder metallurgy method

To address the challenges posed by the high density and low plasticity at room temperature of traditional refractory high entropy alloys (RHEAs), the MoNbVTa0.5Cr RHEA was synthesized through a combination of mechanical alloying (MA) and spark plasma sintering (SPS) techniques. The effects of different sintering temperatures on the microstructure and mechanical properties of the alloy were systematically studied. The MoNbVTa0.5Cr RHEA milled up to 60 h was found to have a metastable dual-phase containing a major BCC (a = 3.1474 Å) and Nb-Ta (a = 3.3058 Å) phase. The sintered MoNbVTa0.5Cr RHEA was composed of BCC phase and a small amount of Ta2VO6 at different sintering temperatures. There were a lot of edge dislocations in the BCC matrix near the BCC/Ta2VO6 interface. With the increase of sintering temperature, the grain size of sintered MoNbVTa0.5Cr RHEA gradually increased, while the mechanical properties gradually decreased with the increase of sintering temperature. When the sintering temperature was 1500 °C, the grain size of the alloy was 2.33 μm, the yield strength was 2783 MPa, the compressive strength was 3346 MPa, and the fracture strain was 20.45 %, showing the best comprehensive properties. And the density of MoNbVTa0.5Cr RHEA was 9.11 g·cm−3 and 26 % lower than that of WNbMoTaV RHEA. The specific yield strength of MoNbVTa0.5Cr RHEA prepared in this research was 295.28 kPa·m3·kg−1, which was superior to most RHEAs reported so far. This sintered MoNbVTa0.5Cr RHEA showed an excellent room temperature compression performance, which can be attributed to the co-existence of BCC phase along with the minor Ta2VO6 phases. The high yield strength of MoNbVTa0.5Cr RHEA was mainly attributed to the substitutional solid solution strengthening of metal atoms, the interstitial solid solution strengthening of O atoms and the grain boundary strengthening of ultrafine grains, with contributions to yield strength of 41 %, 28 %, and 24 %, respectively.

Strengthening of edge prism dislocations in Mg–Zn by cross-core diffusion

The activation of prismatic slip in Mg and its alloys can be beneficial for deformation and forming. Experiments show that addition of Zn and Al solutes have a softening effect at/below room temperature, attributed to solutes facilitating basal-prism-basal cross-slip of prismatic screw dislocations, but a strengthening effect with increasing temperature. Here, the dynamic strain aging mechanism of cross-core diffusion within the prismatic edge dislocation is investigated as a possible mechanism for the strengthening at higher temperatures. First-principles calculations provide the required information on solute/dislocation interaction energies and vacancy-mediated solute migration barriers for Zn solutes around the dislocation core. Results for Mg–0.0045Zn show that cross-core diffusion notably increases the stress for prismatic edge dislocation glide but that the strengthening remains roughly 30% of the experimental strength. Other possible strengthening mechanisms of (i) solute drag of the prism edge dislocation and (ii) solute interactions and/or diffusion within the prismatic screw core, are then briefly discussed with some quantitative assessments pointing toward areas for future study.

Dislocation penetration in basal-to-prismatic slip transfer in Mg: A fracture mechanics criterion

Understanding the transition mechanism from microscopic to macroscopic yielding is crucial for developing high-strength metallic materials. Basal-to-prismatic slip transfer at grain boundaries (GBs) of Mg alloys is known to trigger macroscopic yielding. Here, the penetration behavior of pileup dislocations at a simple basal–prismatic (BP) boundary was analyzed using molecular dynamics simulations. Edge dislocation penetration creates a step in the BP boundary at the intersection with the slip plane, widened via subsequent penetration of dislocations. Many GBs, including the BP boundary, have a regular GB dislocation network that corresponds to a coincidence site lattice. Dislocation penetrations must gradually destroy the initial GB dislocation network, requiring increasing driving force for subsequent dislocation penetrations; thus, slip transfer at the boundary occurs sporadically and stably via the penetration of individual lattice dislocations. As the width of the step created by dislocation penetration increases, a GB dislocation network can be formed in the step, which can stabilize the energy of the step with specific widths. When the energy of step decreases with increasing step width, a smaller driving force is required for the subsequent penetration of dislocations, and thus slip transfer occurs unstably via the penetration of several sequential lattice dislocations. Once the step has a low energy at a specific width, it strongly obstructs dislocation penetration. This formation and disruption of the GB dislocation network cause intermittent penetration of dislocations. Finally, dislocation penetration at the BP boundary is discussed based on a fracture mechanics approach, which well-reproduces the transition between penetration behaviors and the macroscopic yield stress.

Phase- and temperature-driven chiral topological superfluids on a honeycomb lattice

The correlated spinful Haldane model exhibits rich topological phases consisting of chiral topological superfluids (TSFs) and topological spin density waves. However, most of previous studies mainly focus on the case with the fixed hopping phase or at zero temperature. In this paper, we study the attractive spinful Haldane model with arbitrary phase at finite temperature. The chiral TSFs with Chern number C = 2 and 4 emerge driven by the phase and temperature. In particular, the temperature can drive a C = 2 topological superfluid from a trivial normal insulator phase at an appropriate interaction. The bulk topology of all TSFs is uncovered by the Wilson loop method, and confirmed by the responses of edge dislocations.

Thermoelectric enhancement in perovskite type textured Me0.85TiO3 ceramics by synergistic high-entropy and microstructure manipulations

Enhancing the figure-of-merit (ZT) for thermoelectric ceramics essentially needs strategies that aim to concurrently optimize electron and phonon transport properties to decouple their coupling relationship. This work developed 〈001〉 -textured Me0.85TiO3(Me = La, Sr, Ba, Ca) ceramics (LSBC-T) with a texture fraction of 92 % fabricated by a tape casting process combined with template grain-growth method, in which 10 wt% (001) oriented plate-like SrTiO3 serves as template seed and A-site deficient high-entropy (La0.25Sr0.25Ba0.25Ca0.25)0.85TiO3 composite was used as matrix material. A peak ZT of 0.27 was attained at 1073 K in the sample parallel to the tape casting direction which was twice the ZT = 0.13 of the non-textured sample. Quantitative analysis of atomic displacement disorder of A-site elements would provide an atomistic-scale understanding of grain orientation evolution with high texture degree and the low thermal conductivity of 1.79 W/(m‧K) at 1073 K. The complex multi-scale defects consist of cation and oxygen vacancies, edge dislocations, parallel grain boundaries, phase interfaces, nanoscale metal/inorganic coexisting clusters, and metal Bi sandwich layer, which act as additional phonon scattering centers while affecting carrier transport, covering all frequency phonons (100 GHz-15 THz). In addition, multi-scale parallel interfaces, including atomic-scale crystal (00l) plane of SrTiO3 seed, nano-scale “core-shell” interface parallel to the (00l) plane, metal Bi particle forming a sandwich layer in SrTiO3 seed, and “brick-wall” textured grain boundaries, make the electrical and thermal conductivity exhibiting obvious anisotropy in this LSBC-T high-entropy textured ceramics. By utilizing texture engineering in high-entropy systems, this work provides a theoretical foundation and technical support for the advancement of microstructure manipulations to reduce the inherent lattice thermal conductivity, achieve electrical and thermal conductivity anisotropy to decouple the electron–phonon coupling relationship, and thereby enhance thermoelectric properties.

A Volterra edge dislocation problem in second-order elasticity theory

A displacement function technique has been developed to study plane strain problems in second-order elasticity theory for incompressible elastic materials. The formulation culminates in the development of a single inhomogeneous biharmonic equation of the form [Formula: see text] for the second-order displacement function [Formula: see text]. In the second-order, the isotropic stress associated with constitutive behaviour is governed by an inhomogeneous harmonic equation of the form [Formula: see text]. Both functions [Formula: see text] and [Formula: see text] depend only on the solution to the analogous problem in classical elasticity. While there are similarities to the Airy stress function, the displacement function approach enables the evaluation of the first- and second-order displacement fields purely through its derivatives, thus eliminating the introduction of arbitrary rigid body terms normally associated with formulations where the strains derived from a stress function approach need to be integrated. The displacement function approach is applied to develop a second-order elasticity solution to the problem of a Volterra edge dislocation.

Insights into the mechanochemical synthesis of nanostructured PbTe: The role of structural defects

Mechanochemical synthesis of nanostructured PbTe, adding isopropyl alcohol during milling, is promoted by the presence of structural defects such as edge dislocations, amorphous zones, grain boundaries, among others. High-resolution transmission electron microscopy observations revealed that the nanostructured PbTe formation is fundamentally dependent upon crystalline imperfections during the high-energy milling process. Even though defect-dependent mechanisms rule the formation of nanostructured PbTe, oriented-attachment mechanism is also traced and contributes to the PbTe formation. Hence, experimentally, isopropyl alcohol is a key parameter for the mechanochemical synthesis of nanostructured PbTe.

Atomistic investigation of the interaction between an edge dislocation and 1/2 interstitial dislocation loops in irradiated tungsten

By impeding dislocation motion, the irradiation-induced dislocation loops cause irradiation hardening and further embrittlement of plasma-facing tungsten in fusion reactors, leading to its performance degradation. But fundamental questions regarding the mechanisms remain to be clarified and predictive model for loop hardening remains to be built. In this paper, interactions between gliding edge dislocations and interstitial dislocation loops (with Burger vector bL = ½<111>) are studied using atomistic simulations. The influences of bL orientations, dislocation-loop intersection positions, loop sizes, and loading conditions (temperature and strain rate) on the interactions are systematically calculated and analyzed. Results show a large variety of interaction mechanisms, depending mainly on the relative orientations of bL to dislocation slip plane, while slightly affected by loading conditions. Although loops with bL parallel to the plane can be easily swept away by gliding dislocations, loops with bL inclined to dislocation slip plane can strongly pin the gliding dislocation by forming a sessile 〈100〉 segment, which would bend the dislocation line into a screw dipole. Thus, high stress is required for the dislocation line to break away from the inclined loops by cross-slip of each individual arm of the screw dipole coupled with glide of the 〈100〉 segment. On the other hand, increasing temperature and/or decreasing strain rate hardly change the above mechanisms, but monotonically reduce the obstruction by these loops. Simplifying the complex motion of the edge dislocation pinned by the inclined loops as a thermally-activated process of a 1/2[111] edge dislocation overcoming barriers, a hardening model for the inclined loops is proposed. This model well describes the dependence of loop strength on loop sizes, temperatures and strain rates. The model is then applied to predict irradiation hardening at experimental strain rates, and it shows reasonable agreement with experimental results.

Probing the microstructure and deformation mechanism of an FeCoCrNiAl0.5 high entropy alloy during nanoscratching: a combined atomistic and physical model study.

High entropy alloys (HEAs) exhibit superior mechanical properties. However, the nanoscratching properties and deformation behaviour of FeCoCrNiAl0.5 HEAs remain unknown at the nanoscale. Here, we investigate the effect of scratching depth on the microstructural and tribological characteristics of an FeCoCrNiAl0.5 HEA using molecular dynamics simulations combined with a physical model. The scratching force increases significantly as the scratching depth increases. In the lower part of the scratching region, there is a clear atomic movement process, with the load generated in the normal direction causing the atoms to shift downwards. Noticeable shear bands are formed in the subsurface area, and they are both small and narrow compared with the pure Ni. The plastic deformation mechanism of the compressed surface is mainly governed by the formation and expansion of stacking faults during the subsurface evolution process. The evolution process of screw dislocations is similar to that of edge dislocations. In addition, the high strength and deformation resistance of FeCoCrNiAl0.5 HEAs are further evaluated by establishing a microstructure-based physical model. The combined effect of the lattice distortion strengthening and dislocation strengthening promotes the high strength of the FeCoCrNiAl0.5 HEA, which is significantly better than the single strengthening mechanism of pure metals. These results accelerate the understanding of the mechanical properties and deformation mechanisms of HEAs.