Hardness Of Thin Films Research Articles

Heterogeneous Morphologies and Hardness of Co-Sputtered Thin Films of Concentrated Cu-Mo-W Alloys.

Heterogeneous microstructures in Cu-Mo-W alloy thin films formed by magnetron co-sputtering immiscible elements with concentrated compositions are characterized using scanning transmission electron microscopy (STEM) and nanoindentation. In this work, we modified the phase separated structure of a Cu-Mo immiscible system by adding W, which impedes surface diffusion during film growth. The heterogeneous microstructures in the Cu-Mo-W ternary system exhibited bicontinuous matrices and agglomerates composed of Mo(W)-rich phase. This is unique, as these are the slower-diffusing species, contrasting past reports of binary Cu-Mo thin films that exhibited Cu-rich agglomerates. The bicontinuous matrices comprised of Cu-rich and Mo(W)-rich phases exhibited bilayer thicknesses of less than 5 nm. The hardness of these thin films measured using nanoindentation is reported and compared to similar multilayers and nanocomposites in binary systems.

Impact of laser interaction on morphological and mechanical properties of palladium thin film

This research work investigates surface morphology, plasma plume intensity and the hardness of palladium thin film deposited on silicon substrates under the action of laser light. For this purpose, a pulsed Nd:YAG laser (1064 nm, 10 mJ, 12 ns) was used to irradiate the specimen with repetitive laser pulses. The experiment was repeated under the illumination with UV light. The surface morphology of the specimens was examined through an Optical and Field-Emission Scanning Electron Microscopy showing thermal conduction, exfoliation, crater formation, re-deposition of the material, ripples formation, debris, heat-affected zone, holes formation and the formation of nanoparticles. The diameter and the depth of the crater formed on non-UV illuminated Pd thin film were greater than the crater formed on UV illuminated Pd thin film, because of its higher absorption. The photographs of the plasma plume were captured with a computer-controlled image capture system and examined by image processing software. The intensity of UV-illuminated Pd thin film was higher than non-UV illuminated Pd thin film because UV illumination induces defects in the specimen that have additional electronic states. These defects cause higher absorption and more ionization of the target material and emerge a more luminous plasma plume. A nanoindentation test was applied on the material surface to investigate the mechanical properties such as hardness and elastic modulus of the target specimen. The hardness and elastic modulus of the material were increased by cumulative laser shots.

Operando Stress Evolution in Hard Carbon Anodes – Insight into the Mechanical Degradation Induced Failure Mode in Rechargeable Sodium Ion Batteries

Microstructural instabilities in electrodes arising from cycling induced stress is a primary failure mode in rechargeable batteries. Therefore, a quantitative knowledge of the cycling induced stress evolution in rechargeable battery electrodes is important for understanding the electrode microstructural instabilities during cycling that can potentially inform the electrode design to prolong battery cycle life. The cycling induced stress in electrodes typically arises from the volume changes associated with insertion/extraction of the electroactive species in the electrode matrix. For example, operando measurement of lithiation-delithiation induced stress in graphite electrodes that typically show 10% volume change has previously resulted in useful information that correlates well with the lithiation-delithiation mechanism in graphite anodes1. The size of the shuttling-electroactive species can be taken as an indicator of the cycling induced stress magnitude that drives the electrode microstructural instabilities. In this regard, quantification of the cycling induced stress in rechargeable Na-ion battery electrodes is warranted for understanding mechanical degradation induced failure modes owing to the larger size of the electroactive species, i.e., Na ions (vs. Li-ion).Hard carbons as potential anodes in rechargeable sodium ion batteries has gained considerable attention in the recent past due to their superior Na-ion storage capability (vs. graphite that is a canonical anode in rechargeable lithium-ion batteries). However, hard carbon anodes typically show significant capacity fade that can potentially arise from cycling induced mechanical degradation of the anodes. Operando stress measurements coupled with comprehensive electrode microstructural characterization will provide valuable insights in this context. Here we report on the operando stress evolution in hard carbon anodes in rechargeable sodium ion batteries as probed by Multiple Optical-beam Sensing (MOS) technique that basically involves monitoring the spacings among a group of laser spot (Fig. 1). Preliminary measurements have shown that the stress correlates with the potential with a maximum around 12 MPa in compression during sodiation and tensile stress of ~ 2MPa during desodiation. Operando stress measurements are performed in hard carbon anodes in two different electrode configurations – typical composite anodes (with binder and conductive agents) and hard carbon thin film anodes (without binder and conductive agents). The thin film configuration is considered to evaluate intrinsic stress response in hard carbon anodes in absence of any secondary phase. A comparison of operando stress response in these two types of hard carbon anodes along with comprehensive electrode microstructural characterization will be presented. Additionally, attempts will be made to shed light on the current debate in the mechanism of sodium storage in hard carbon anodes by comparing operando stress response of hard carbons from multiple sources along with their structural characterization (Raman, XPS, surface area etc.). V. A. Sethuraman, N. Van Winkle, D. P. Abraham, A. F. Bower, and P. R. Guduru, Journal of Power Sources, 206, 334–342 (2012). Figure 1

Contact fatigue of thin hard diamond-like carbon films on M50 steels under cyclic spherical micro-indentation

Contact fatigue behaviors of thin hard diamond-like carbon (DLC) films on M50 steels during cyclic spherical micro-indentations were investigated. The stress-strain evolution of the entire system was analyzed by finite element methods. The film fracture mechanisms and interfacial bearing responses under monotonic and repeated contacts were comprehensively explored. Concentrated tensile and shear stresses were found to, respectively, govern the initiation and propagation of the surface ring cracks. Elevated tensile stresses at the initiation and epilogue of each indentation cycle enhanced bottom radial cracking. At the interfaces, the maximum tensile (σnmax) and shear (σtmax) stresses occurred at the end of unloading and loading processes, respectively. With increasing maximum indentation forces, σnmax initially increased and then gradually decreased, while σtmax increased monotonically.

Microstructural stability and mechanical property of AlCrFeMoTi high-entropy amorphous alloy thin films under He+ ions irradiation

High-entropy amorphous materials have recently proved exceptional radiation resistance, showing potential as a candidate materials for nuclear industry applications. This study synthesized nearly equi-atomic AlCrFeMoTi high-entropy amorphous thin films with a thickness of about 499 nm using magnetron sputtering. The prepared films were subjected to low dose, 0.5 MeV He+ ion irradiation, with varying irradiation damage ranging from 0.01 to 0.1 displacement per atom (dpa). Increasing the irradiation dose led to a decrease in the radius of the inner diffraction halo (r) and an increase in the crystal-like order, indicating an irradiation-induced structural relaxation process within the amorphous matrix. This relaxation results in more efficient atomic packing, yielding a denser amorphous structure and enhanced hardness of AlCrFeMoTi high-entropy amorphous thin films. This study demonstrates that AlCrFeMoTi high-entropy amorphous thin films exhibit remarkable radiation resistance, with stable microstructure and mechanical properties under He+ irradiation, making them promising candidates for applications in the nuclear industry.

Conformal Low‐Temperature Molecular Layer Deposited Coatings as Interface Modifications to Support Ceramic Protective Films on Macroscopic Flexible Devices

Flexible devices often need a protective coating when operating in harmful environments, ranging from mild ambient conditions to a biologically active environment of the human body. The flexibility poses a problem for traditional encapsulation solutions, as those make the device bulky and limit functionality by applying an external casing. Alternatively, fully conformal encapsulation of a device of arbitrary shape can be realized with thin‐film encapsulation (TFE) without altering device dimensions. Yet, TFE is susceptible to fail under mechanical stresses, especially when a hard ceramic coating is applied on a polymer. Reliability of TFE can be enhanced by altering the elasticity of the hard and brittle thin films, by adding softer layers in between sample and barrier. Herein, molecular layer deposited (MLD) metal‐linked trioxysilylheptanoate (M‐TOSH) films are studied for coating of large devices to conformally and uniformly tune the interface between polymer and atomic‐layer‐deposited protective film. The results show that M‐TOSH process scales to large chambers; parameter optimization leads to superior film quality and lowers elastic modulus. Conformality, tested with home‐built macroscopic test device, finds the process suitable for 3D parts. Final testing reveals that ten cycles of MLD interlayer double the crack‐onset‐strain from 0.26% to 0.51%.

Tribological Properties of Hard TiB2 Thin Films Prepared at Low Temperatures Using HiPIMS

Magnetron-sputtered WS2 composite thin films are solid lubricants with excellent performances. However, the low hardness of the WS2 thin films necessitates the further improvement of their wear resistance. For this purpose, an effective strategy is to alternately deposit or code posit WS2 and a hard phase, such as TiB2, to form hard lubricant thin films. Herein, a TiB2 thin film was prepared under the same conditions as those used for depositing the WS2 thin film with a dense structure and excellent tribological properties. Because of the high deposition energy of high-power impulse magnetron sputtering (HiPIMS), the TiB2 thin film possesses a dense structure and leather-like flat surface (hardness = 24.17 GPa). The friction coefficient of the film under different loads ranges between 0.6 and 0.8. The wear rate of the thin film increases with load, mainly because of fatigue wear and abrasive wear. Under high loads, obvious furrow-like wear marks are observed. At different sliding frequencies, except 8 Hz, the friction coefficient of the film ranges from 0.6 to 0.8. The main wear mode is fatigue wear, particularly at increasing sliding frequencies. Although the film possesses a relatively high friction coefficient, its wear resistance is excellent (minimum wear rate = 1.96 × 10−6 mm3/(N·m)).

Surface modifications to reduce wear in hot extrusion of copper

During hot extrusion of copper, the material tends to stick to the extrusion die due to strong adhesive forces between hot working steel and copper at high temperatures. In this context, surface modifications like nanocomposite coatings deposited by plasma enhanced chemical vapor deposition or boriding of nickel-based alloy 718 (DIN 2.4668) create hard and wear resistant thin solid films that offer high temperature stability. Ti–Si–B–C–N nanocomposite coatings consist of nanocrystalline grains embedded in a thin amorphous matrix. Due to this particular nanostructure, hardness values of up to 39.3 GPa were reached. Boriding of alloy 718 leads to formation of phases consisting of alloying elements like nickel, iron, and chromium and the diffusing element boron. The borides form a boriding zone that offers high hardness. Extrusion of Ø122 mm × 300 mm copper billets preheated to 850 °C was carried out and adhesive wear on tool's surfaces was analyzed. The comparison between hot working steel DIN 1.2367 without surface modification and with Ti–Si–B–C–N coating or borided alloy 718 showed remarkable differences between conventional tools made of hot working steels/alloy 718 and tools with surface modification. A strong decrease particle adhesion was observed.

Scratch hardness of diamond-like carbon (DLC) coatings deposited by closed-field unbalanced magnetron sputtering

Thin coatings are subject to scratch and wear damage in tribological applications. Scratch hardness numbers are used to evaluate scratch and abrasive wear resistance. Few studies have measured the scratch hardness of thin films, and a proper scratch hardness measurement method for thin coatings is still lacking. In this study, the scratch hardness of these DLC coatings was measured at both micro-scale and nano-scale, respectively. The micro-scratch test using a 200 µm tip is an inapplicable method because the substrate effect has dominated the scratch hardness measurement. On the other hand, a nano-scratch hardness test using a sharper tip is an effective method to measure the scratch hardness of thin coatings. Although the scratch hardness introduces a lateral force compared with the indentation hardness, it well correlates with the nano-indentation hardness. The ratio of the scratch hardness to the indentation hardness is close to 1 for DLC coatings due to the amorphous structure. It proves that the tangential force induced by scratching does not influence the hardness property. In addition, a simple approach is proposed to obtain the scratch hardness of DLC coatings qualitatively without width measurement.

Effect of Si content on the thermal stability and oxidation resistance of arc-deposited TiAlSiN films with cubic structure

Recently, TiAlSiN thin films have attracted increasing research interest due to their potential to have simultaneously enhanced hardness, thermal stability, and oxidation resistance compared with Si-free TiAlN films. Previous studies have revealed that a relatively low Si content (2.1–6.0 at.% Si) is essential for the phase stability and hardness of TiAlSiN thin films. Despite the optimum Si content for the hardness of TiAlSiN thin films being proposed, a systematical study concerning the optimum Si content for tailored phase stability, thermal stability, and oxidation resistance of TiAlSiN thin films is still missing. Here, we arc-deposited Ti1-x-zAlxSizN thin films (x = ~0.45, 0.01 ≤ z ≤ 0.08), and investigated the dependence of their structure, mechanical properties, thermal stability, and oxidation resistance on Si content. XRD analysis reveals the transformation from single-phase cubic structure for z ≤ 0.06 to a cubic-wurtzite dual-phase structure for z = 0.08. Increasing the Si content of cubic-structured Ti1-x-zAlxSizN thin films conduces a continuous increase of hardness (H) from 29.3 ± 0.5 GPa for z = 0.01 up to 37.3 ± 0.7 GPa for z = 0.06, whereas the w-AlN formation leads to a drop of H to 32.8 ± 0.6 GPa for z = 0.08. Furthermore, enhancing the Si content from z = 0.01 to z = 0.06 continuously improves film thermal stability, where the Ti0.48Al0.46Si0.06N film presents the highest hardness values within the whole studied temperature range (as-deposited, 800–1200 °C). All Ti1-x-zAlxSizN films undergo age-hardening, with peak H of 33.3 ± 1.0 GPa at 1000 °C for z = 0.01, 35.0 ± 0.6 GPa at 1100 °C for z = 0.02, 35.4 ± 0.5 GPa at 1100 °C for z = 0.03, 40.2 ± 0.7 GPa at 1200 °C for z = 0.06, and 37.8 ± 0.6 GPa at 1100 °C for z = 0.08. Additionally, the oxidation resistance of Ti1-x-zAlxSizN films at 800–1000 °C is improved with increasing Si content, due to the suppressed transformation of anatase-to-rutile TiO2 and the promoted formation of a top dense oxide scale. After oxidation at 900 °C for 15 h, the Ti0.54Al0.45Si0.01N film has been completely oxidized, whereas Ti0.53Al0.45Si0.02N, Ti0.51Al0.46Si0.03N, Ti0.48Al0.46Si0.06N and Ti0.45Al0.47Si0.08N films exhibit oxide scales of ~1.7, ~1.4, ~1.2 and ~0.9 μm, respectively. Overall, we propose z = 0.06 as the optimum Si content for the over-rounded performance of Ti1-x-zAlxSizN thin films.

Effect of ytterbium on hardness and color of titanium nitride thin films

Yb mononitride (YbN) has a B1 (NaCl-type) structure similar to the structure of titanium nitride (TiN), which makes it a candidate for use in new hard coating materials via solid-solution hardening. Ternary system (Ti–Yb–N) thin films with various Yb contents were prepared on Si substrates by pulsed laser deposition, and compositional analysis confirmed that the resultant films contained the expected elements. Phase identification revealed that the ternary nitride (Ti1−x Yb x )N thin films were all single-phase thin films that comprised YbN in TiN as a solid solution in the form of a B1- (Ti1−x Yb x )N phase. Although the hardness of the Ti–Yb–N thin films could be increased to a certain degree compared with that of a pure TiN thin film, the improvement was not significant. A change in the optical properties of the (Ti1−x Yb x )N thin films was indicated by a change in their color from gold to copper to silver with increasing x. This effect could make such thin films suitable for use as decorative coatings that are resistant to oxidation.

Leveraging Deep Neural Networks for Estimating Vickers Hardness from Nanoindentation Hardness.

This research presents a comprehensive analysis of deep neural network models (DNNs) for the precise prediction of Vickers hardness (HV) in nitrided and carburized M50NiL steel samples, with hardness values spanning from 400 to 1000 HV. By conducting rigorous experimentation and obtaining corresponding nanoindentation data, we evaluated the performance of four distinct neural network architectures: Multilayer Perceptron (MLP), Convolutional Neural Network (CNN), Long Short-Term Memory network (LSTM), and Transformer. Our findings reveal that MLP and LSTM models excel in predictive accuracy and efficiency, with MLP showing exceptional iteration efficiency and predictive precision. The study validates models for broad application in various steel types and confirms nanoindentation as an effective direct measure for HV hardness in thin films and gradient-variable regions. This work contributes a validated and versatile approach to the hardness assessment of thin-film materials and those with intricate microstructures, enhancing material characterization and potential application in advanced material engineering.

Fractal dimension of heights facilitates mesoscopic mechanical properties in ternary hard film surfaces

Hardness of thin films is a noteworthy property in the electronic and mechanical industry and is generally observed to be dependent on the degree of roughening facilitated from surface heights' surface spatial heterogeneity at the mesoscopic observation scale. Nonetheless, owing to enhanced scale fluctuations and higher-order central moments, conventional parameters provide limitations and errors in capturing the spatial heterogeneity of surfaces. Herein, we have utilized scale-independent fractal parameters to analyze the spatial heterogeneity of surface heights in Ti1−xSixN ternary hard films deposited with varying Si doping concentrations using sputtering technique. The fractal dimension, lacunarity coefficient, Moran index, surface entropy, Otsu's separability, and fractal succolarity were computed to provide an overarching understanding of the surface heights' spatial heterogeneity. Principal component analysis was employed on the data sets to identify the parameter(s) accounting for the maximum variance and accordingly, the structure–property relation between spatial heterogeneity of surface and hardness is analyzed and discussed in the context of the fractal dimension of surface heights. The results indicate the possibility of mesoscopic surface engineering and, consequently, tuning of hardness and modulus of elasticity in Ti1−xSixN hard films by mere changing of surface spatial heterogeneity facilitated by the fractal dimension of surface heights.

Effects of Oxygen Pressure on the Microstructures and Nanomechanical Properties of Samarium-Doped BiFeO3 Thin Films.

In this study, samarium (Sm-10at%)-doped BiFeO3 (SmBFO) thin films were grown on platinum-coated glass substrates using pulsed laser deposition (PLD) to unveil the correlation between the microstructures and nanomechanical properties of the films. The PLD-derived SmBFO thin films were prepared under various oxygen partial pressures (PO2) of 10, 30, and 50 mTorr at a substrate temperature of 600 °C. The scanning electron microscopy analyses revealed a surface morphology consisting of densely packed grains, although the size distribution varied with the PO2. X-ray diffraction results indicate that all SmBFO thin films are textured and preferentially oriented along the (110) crystallographic orientation. The crystallite sizes of the obtained SmBFO thin films calculated from the Scherrer and (Williamson-Hall) equations increased from 20 (33) nm to 25 (52) nm with increasing PO2. In addition, the nanomechanical properties (the hardness and Young's modulus) of the SmBFO thin films were measured by using nanoindentation. The relationship between the hardness and crystalline size of SmBFO thin films appears to closely follow the Hall-Petch equation. In addition, the PO2 dependence of the film microstructure, the crystallite size, the hardness, and Young's modulus of SmBFO thin films are discussed.

Radiation hardness evaluation of ε-Ga2O3 thin-film devices under swift heavy ion irradiation

The ultra-wide band gap (∼4.9 eV) and extremely large breakdown field strength (∼8 MV/cm) enable ε-Ga2O3 as an ideal materials candidate for high-performance power devices and solar-blind photodetectors. For the purpose of deep space applications explorations, comprehensive study of the effects of particle irradiation on the lattice stability and electronic properties of ε-Ga2O3 are of pivotal importance. In this work, leveraging a unique Ta radiation source, we interrogate the radiation hardness of ε-Ga2O3 thin films after 1907 MeV Ta swift heavy ion (SHI) irradiation. Detailed characterizations of the structural and optical properties show that the morphology and lattice structure are disrupted, with an increase of the band gap. Additionally, X-ray photoelectron spectroscopy experiments combining density functional theory calculations corroborate extrinsic flux-induced high concentration defects in the film, which lead to truncated photo-response performance of the device. However, even upon irradiation with a fluence of 5 × 1010 cm−2, the overall performance of the device remains robust and substantial. This outstanding radiation hardness of ε-Ga2O3 thin films rationalizes their potential usage for space applications.

Adatom controlled emergence of high hardness in biocompatible beta-Ti3Au intermetallic thin film surfaces

There is growing international interest in hard biocompatible thin film surface coatings to extend the lifetime of medical implants. Parameters of the physical vapour deposition technique can be utilized to fine tune the microstructure and resulting properties of the growing thin film surface by modifying the adatom mobility of the incoming species. This work investigates the evolution of high hardness and biocompatibility of sputter deposited beta-Ti3Au intermetallic thin film surfaces as a function of growth temperature and pressure. Titanium and gold are sputtered in an optimised 3:1 ratio over glass and Ti6Al4V substrates at varying pressures of 0.3 to 1.2 Pa and temperatures of 25 to 450°C. The microstructure and crystallinity of the deposited films improved with reduction in pressure from 1.2 to 0.3 Pa but development of the β-Ti3Au intermetallic compound occurred at temperatures above 350˚C. The density of the films also increased with reducing pressure, whereas improvement in their columnar structure was observed with increasing substrate temperature. These microstructural changes caused by adatom mobility variation, led to the emergence of superior mechanical surface hardness, reaching a peak value of 12.5 GPa for films grown at 0.3 Pa and 450°C. All thin film surfaces were highly biocompatible with ion leaching levels below 1 ppm, and films deposited at lower pressure exhibited much safer cytotoxic profiles against L929 mouse fibroblasts. This work demonstrates the emergence of high hardness and biocompatibility in Ti3Au thin film surfaces with potential as next generation medical implant coating materials.

Influence of Fluorine Doping on Hardness and Compressive Stress of the Diamond-Like Carbon Thin Film

Influence of Fluorine Doping on Hardness and Compressive Stress of the Diamond-Like Carbon Thin Film

Microstructure and Mechanical Properties of TiN/Ti2AlN Multilayers

Titanium nitride (TiN) thin films deposited by high-power pulsed magnetron sputtering usually have a high compressive residual stress, which is not conducive for the adherence of TiN thin films. This study investigated the potential of Ti2AlN for releasing the compressive residual stress of HPPMS-deposited TiN thin films and evaluated the adherence strength and hardness of TiN/Ti2AlN multilayers by introducing the Ti2AlN MAX phase to form TiN/Ti2AlN multilayers. The results showed that smooth TiN/Ti2AlN multilayers with the TiN (111) and Ti2AlN (002) textures were successfully synthesized by HPPMS deposition and subsequent vacuum annealing. The compressive residual stress in TiN was released by Ti2AlN. The adherence strength of the TiN/Ti2AlN multilayers was improved after the release of the compressive residual stress, and the hardness of TiN/Ti2AlN multilayers was close to the annealed TiN. This study provides a novel approach for releasing the residual stress of hard ceramic thin films using the MAX phase.

Investigation of upward speed and thickness effects on optical and mechanical properties of hard transparent thin films deposited on polycarbonate substrate

In the present work, nanomechanical behaviors and optical properties of the nanohybrid thin films coated on the polycarbonate (PC) substrates were investigated. Tetraethyl orthosilicate (TEOS), 3-glycidoxypropyl-trimethoxysilane (GPTMS) and aluminum tri sec-butoxide were used as main precursors through very simple and repeatable sol-gel process. Optical, chemical, structural, morphological and mechanical characteristics of the samples were studied by ellipsometry, UV/vis spectroscopy, ATR-FTIR, EDS, XRD, FE-SEM, TEM and nanoindentation-nanoscratch methods. It was found that upward speed had an important effect on the nanomechanical properties while optical properties remained constant. The obtained results indicated that the refractive index of the prepared thin films were significantly lower (1.483) than PC substrate (1.58) led to increase the transmittance that was measured 89 % compared to pristine PC (86 %). Nanohybrid thin films increased PC hardness and elastic modulus to 0.45 and 7.4 GPa respectively at upward speed 5 mm/s. The friction coefficient was decreased to 0.23 and the pencil hardness was 5H at 1887 nm thickness coating at 9 mm/s upward speed.

Nano-scale mechanical characteristics of epitaxial stabilization ZrTiN/NbN superlattice coatings

Protective hard thin films are necessary in industrial engineering under extreme condition. In that regard, superlattices with epitaxial stabilization have shown to be a potential approach. The ZrTiN/NbN system was chosen due to the similar lattice parameter and crystal structure. The phase transition from c-NbN to h-NbN was presented while NbN sub-layer was relatively thick in the superlattices, owing to higher VEC (valence electron concentration) of NbN. HRTEM images confirmed that h-NBN led to the loss of epitaxial growth, and thus the coatings demonstrated polycrystalline structure. The superlattices showed no cracks after indentation, possessing stronger crack resistance than ZrTiN (Kc = 3.22 MPa √ m) and NbN (Kc = 2.70 MPa √ m) monolayers. A 3-scan procedure was conducted and multilayers exhibited the staircase-like curve during scratching. The wear volume of multilayers was significantly lower than monolithic films, however, the existence of h-NbN would deteriorate the wear resistance and elastic recovery of the coatings. It can be concluded that epitaxial ZrTiN/c-NbN superlattices exhibited not only favorable mechanical performance but also excellent tribological behavior.