Sliding Wear Tests Research Articles

A practical approach to fabrication of nano-Al2O3 reinforced MMC coatings by cold spray: Characterization of nanomechanical and tribological performance

Cold spray is a crucial solid-state deposition technique involving high-speed spraying of different-sized particles onto a base material. In this study, Ni-based powder reinforced with different proportions of nano-Al2O3 particles was sprayed onto Al6061 alloy by cold spray to improve the coating performance. Nanoparticles are very difficult to deposition as they are affected by the aerodynamic forces generated during cold spraying. With a practical approach, nanoparticles were agglomerated with micron-sized feedstock powders, and nanoparticles in the sprayed powder acted as larger particles and successfully defeated the aerodynamic force. The effects of adding nano-particles on the microstructural, nanomechanical, and tribological properties were investigated. Microstructural analyses revealed that MMC coating layers comprised ceramic particles and metal matrix (Ni and Zn). Due to the high spraying speed, the nano-particles were spread in the relatively ductile matrix formed by Ni and Zn. The micro- and nanohardness values were increased with nanoparticle volume by two mechanisms. In the first mechanism, the hard particle volume increased with the addition of nano powders, and in the second mechanism, the plastic deformation of the matrix increased due to the nano-particles. The sample without nanoparticle reinforcement exhibited plastic deformation during the initial stage of the nanoscratch test. The dry sliding wear test results showed that the nano-Al2O3-reinforced spraying powders increased the wear resistance approximately 1.9 times. According to FESEM and EDS examinations of worn surfaces and WC counter-bodies, nano-particles reduced the transferred layers caused by adhesion to the abrasive counter-body. In addition, the nano-particles were provided a more homogeneous hard particle distribution and improved wear performance.

Exploring the Interplay between Tribocorrosion and Surface Chemistry of the ASTM F139 Surgical Stainless Steel in Phosphate-Buffered Saline Solution.

Surgical ASTM F139 stainless steel is used for temporary fixtures in the biomedical field. Tribocorrosion is a major concern in this application. The aim of the present work was to study the interplay between tribocorrosion behavior and the surface chemistry of the ASTM F139 stainless steel in phosphate-buffered saline solution (PBS). Sliding wear tests were conducted against alumina balls at different electrochemical potentials: open circuit potential (OCP), cathodic potential (-100 mV versus the OCP), and anodic potentials (+200 mVAg/AgCl and +700 mVAg/AgCl). The normal load was 20 N. The wear volume was estimated based on micrographs obtained from the wear tracks using confocal laser scanning microscopy. Moreover, the wear tracks were also examined by scanning electron microscopy (SEM). The surface chemistry of the ASTM F139 specimens was analyzed by X-ray photoelectron spectroscopy (XPS). The wear volume was dependent on the electrochemical potential, being maximized at +700 mVAg/AgCl. Delamination areas and grooves were observed in the wear tracks. Detailed assessment of the surface chemistry inside the wear tracks allowed identification of the main chemical species and their relative quantities, thus enabling correlation of the passive film composition with the observed tribocorrosion behavior.

Exploring the Friction and Wear Mechanisms of Nickel Titanium Alloy Fabricated by Laser Powder and Wire-Based Directed Energy Deposition

The NiTi alloy has attracted significant interest owing to its notable wear and corrosion resistance, suggesting the significant promise of utilizing additively manufactured NiTi alloys in tribological applications. In this study, dry sliding wear tests with sliding velocity of 0.1 m/s for total distance of 250 m at room temperature, 50 °C, 100 °C, and 200 °C were carried out on samples of NiTi alloy samples fabricated using laser powder and laser wire directed energy deposition (LP-DED and LW-DED) processes. Enhanced friction and wear behavior of LP-DED samples were captured at lower temperatures due to higher hardness and the stable dominating NiTi B2 austenite phase in the sample microstructure as confirmed from x-ray diffraction (XRD) analysis. Accumulated transferred material at lower temperatures played a crucial role in modifying the wear mechanisms. However, at higher temperatures both LP-DED and LW-DED samples presented similar wear mechanisms.

Sliding wear study of the Inconel-625 clad deposits by microwave heating on SS-304

In this present study, the Inconel-625 powder was used for the surface modification of SS-304 alloy by utilizing the concept of a hybrid microwave heating technique. The XRD analysis shows the presence of various carbide and Laves phases in addition to a Ni-Cr-Fe-based face-centred-cubic matrix in the modified clad layer. The microstructural analysis revealed that the developed clad was metallurgically bonded with the substrate and free from any interfacial cracks. The modified layer mainly consists of two regions: cellular (matrix) regions and grain boundaries (GBs) regions. The average porosity in the modified clad layer was evaluated to be about 1.65%. The average microhardness (440 ± 45 HV) of the modified clad layer was observed to be about 2.1 times the base metal microhardness (210 ± 10 HV). The clad specimens exhibited a considerably lower wear rate (about 2.8 times less weight loss) than the substrate SS-304 during the dry sliding wear test. The shallow grooves, craters, and material debonding were the typical fracture features associated with the clad surfaces during rubbing when examined under a scanning electron machine apparatus.

Studies on wear and microstructure assessment of WC-Co reinforced iron based HVOF coating

This research work uses a High-Velocity Oxy Fuel (HVOF) system to create a cermet based WC-10Co reinforced with a durable Iron-based (FeNiCrMo) advanced composite coating to resist high-temperature sliding wear on an ASTM-SA213-T11 steel substrate. Metco 41C (70%) + WC-10Co (30%) were mechanically blended. Then, feedstock was utilized by the HVOF system to create coatings. The base alloy and the coatings were subjected to various metallurgical and mechanical characterizations. Dry sliding wear test of base alloy and coating, were evaluated using the pin-on-disc device. The test was performed by varying parameters of load 10 N and 20 N with variable temperature of 200 °C, 300 °C and ambient conditions. SEM/EDS and XRD techniques were used to examine the worn samples and to identify the formation of new phases during wear test. The wear characteristics pertaining to wear rate, volume loss, and COF were computed. The coating exhibits both intermetallic phases, such as Mo2C and Co3W3C, and challenging stages, such as Cr3C2, Ni3C, W2C, Fe2C, and SiC. There has been a resultant improvement in wear resistance and hardness of coating relative to the base alloy.

Fabrication and wear behavior of TiC/TiB2-reinforced NiAl intermetallic matrix composites

Combustion synthesis (CS) is a well-known technique for manufacturing intermetallic compounds and intermetallic-matrix composite materials. This research focuses on fabricating NiAl-matrix composites with varying TiC/TiB2 contents as reinforcement, achieved by the combustion synthesis method. The chemical reactions that yield the final NiAl–TiC–TiB2 compounds were interpreted using thermodynamic calculations. The phase analysis and morphology of the composites were investigated using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) characterization techniques, respectively. The findings demonstrate that the NiAl matrix contains evenly distributed TiC–TiB2 ceramic-based particles, and no oxidation of reactants occurred during the combustion reaction. With an increase in the TiC–TiB2 reinforcement phases from 0 to 15 wt %, the hardness of the NiAl–TiC–TiB2 product significantly rose from 496 to 1015 Vickers, while the porosity increased from 24% to 39%, attributed to the reduced quantity of melted NiAl available to fill the pores. Examining tribological behavior in synthesized composites involved combining experimental-numerical methods, utilizing sliding wear tests and artificial neural network (ANN) modeling. The wear results revealed decreasing wear rates with reduced loads (from 35 N to 25, and 15 N) and higher TiC/TiB2 ceramic content. Iron traces at C0 and C10 worn samples were 2.47 and 26.18 wt % respectively, which indicates enhanced hardness. The experimental data were used to train and test an artificial neural network (ANN) and statistical analysis revealed a remarkable accuracy of 91% for the ANN model in predicting friction coefficients within SHS-processed composites, as indicated by the R2 value of 0.91 and a MAPE of 6.47.

Insights into the microstructure evolution and wear resistance of Nano-TiC particles reinforced High-Cr hot work die steel

The current study innovatively proposed to prepare TiC nanoparticles reinforced high-Cr hot work die steels through an aluminum master alloy. The influences of TiC nanoparticles on the microstructure and wear resistance of high-Cr hot work die steels were thoroughly investigated. It was found that the addition of nanoparticles refined the pro-eutectoid ferrite in the as-cast condition, and the granular pearlite in the isothermal spheroidized condition, respectively. After receiving the quenching and tempering heat treatment, the size of lath martensite, retained austenite and nanosized precipitates were reduced. The TiC nanoparticles were used as heterogeneous cores to improve the nucleation rates of austenite and ferrite during phase transformation. The finer grains with more grain boundaries and nanoparticles refined the size of tempered microstructure of high-Cr hot work die steels. In ball-on-plate reciprocating sliding wear tests, it was found that the presence of TiC nanoparticles enhanced the wear resistance of high-Cr hot work die steels under various test conditions. The nanoparticles increased the strength of the substrate and inhibited the formation of cracks. More grain boundaries and nanoparticles hindered the migration of dislocations, which resulted in less plastic deformation. Also, the nanoparticles could partially withstand the external load during the relative motion. The results obtained in this research provide applicable values for optimizing the strength-ductility and tribological performance of hot work die steels.

High entropy (HfTiZrVNb)B2 ceramic particulate reinforced Al matrix composites: Synthesis, mechanical, microstructural and thermal characterization

This study aims to introduce a novel type of particulate reinforced Al matrix composite. High entropy (HfTiZrVNb)B2 ceramic particulate reinforced Al matrix composites were produced via a combined process of different powder metallurgy methods. Firstly, boride compounds (HfB2, TiB2, ZrB2, VB2, NbB2) were synthesized in the laboratory scale using the related metal oxide, boron oxide, and magnesium by mechanochemical synthesis (MCS) and leaching processes under optimum conditions. Secondly, the synthesized and purified boride powders were mixed in equimolar ratios using a planetary ball mill for 72 h, and they were sintered at 2000 °C under 30 MPa via spark plasma sintering (SPS). Thirdly, equimolar high entropy (HfTiZrVNb)B2 bulks were crushed, converted into powder forms, and added into Al powders at different amounts as 1, 2, 5, 10, and 15 wt %. Lastly, these powder blends were mechanically alloyed in a vibratory ball mill for 6 h, cold pressed and pressureless sintered at 630 °C for 2 h. For characterization techniques, X-ray diffractometry (XRD), thermal analysis, scanning electron microscopy/energy dispersive spectrometry (SEM/EDS), density measurements using pycnometer and Archimedes' methods, microhardness and dry sliding wear tests were conducted on the sintered composites. The highest hardness (∼1.5 GPa) and the lowest wear rate (∼0.0012 mm3/Nm) were obtained in the Al-15 wt % (HfTiZrVNb)B2 sample.

Microstructure and tribological properties of solid lubricant-doped CMT-WAAMed Stellite deposits

AbstractA large share of the world’s total energy consumption is used to overcome friction. Therefore, low friction wear-resistant materials are needed. Solid lubricants are solid-phase materials that can reduce friction at different temperatures between two surfaces sliding against each other without the need for a grease or liquid oil medium. In this study, Cold Metal Transfer Wire Arc Additive Manufacturing (CMT-WAAM) was used to deposit solid lubricant (WS2, MoS2, CaF2) doped hypoeutectic Stellite alloy. Fabricated deposits possessed crack- and pore-free microstructures consisting of γ-Co and M7C3 carbide eutectics embedded with chromium sulfides and microhardness values of ~ 530 HV1. They were also tested in self-mated unidirectional sliding wear tests in dry conditions at room temperature (RT) and at 300 °C in an air atmosphere. The results showed that the dynamic coefficient of friction (COF) decreased ~ 27% at RT and ~ 21% at 300 °C without losing the wear properties. During sliding wear tests severe strain hardening occurred and γ-Co was found to transform to ε-Co. The developed deposits can be used as hard facings or 3D printed components in applications that require good sliding wear properties at different temperatures such as metal forming tools, power transmission components, valves, and internal parts of combustion engines.

Microstructural evolution and its influence on the wear resistance of a laser directed energy deposited Ni-based single crystal superalloy

The wear behavior of Ni-based single crystal (NBSC) superalloy SRR99 fabricated by laser-directed energy deposition (LDED) is investigated and compared with that of its cast counterpart. While γ’ precipitate size in the latter is > 400 nm, that in the former is an order of magnitude lower. Dry sliding wear tests reveal that the wear rate and coefficient of friction of the LDED alloy are 75 % and 20 % lower than that of its cast counterpart, respectively. Detailed transmission electron microscopy investigation of the wear-tested cast alloy indicates that there is orientation change and formation of nanoscale grains only at the top layer of the worn surface, whereas regions below undergo moderate plastic deformation via dislocation slip. In contrast, the sub-surface of the worn LDED alloy has a graded microstructure, with a composite of NiO/γ-Ni on the top, γ’ free nano-grains in the middle, and a highly deformed nanoscale layer at the bottom. The improved wear behavior of the LDED alloy is attributed to its higher dislocation density, finer γ’ precipitates, and the formation of this graded microstructure. Finally, a detailed description of mechanisms that lead to the formation of this unique graded microstructure is provided.

Tribological and electrochemical behaviors of FeCoNiCrMox HEA coatings prepared by internal laser cladding on 316L steel tube

In order to improve the performance of the inner wall of the 316L hydraulic cylinder, FeCoNiCrMox (x = 0.2, 0.4, 0.6) high entropy alloy coatings were prepared by laser cladding. The effects of the Mo element on the phase, microstructure, hardness, and tribological as well as electrochemical behaviors of the coating were investigated. The results show that the coatings consist of the FCC phase. The FCC phase increases, and the grain orientation becomes more complex with increased Mo element content. The coatings are mainly composed of columnar and equiaxial crystals. Mo0.4 coating has the finest grain structure, resulting in the coating with a maximum hardness of 421.99 HV, 2.11 times that of the substrate. The nanoindentation test shows that the elastic modulus of the HEA coating increases with the increase of Mo content. The dry sliding wear test shows that adding the Mo element improves the wear performance of the coating. The wear volume loss and wear rate of Mo0.4 coating were the lowest, 12.242 mg and 2.88 × 10−4 mm3•N−1•m−1, respectively. In the 3.5 wt% NaCl solution, the polarization curves and EIS results indicated that adding the Mo element improved the corrosion resistance of the coating. The FeCoNiCrMox coatings significantly improved the hardness, tribological, and electrochemical behaviors of the 316L substrate.

Influence of Homogenization and Quench-Aging Heat Treatments on Dry Wear Behavior of Al-40Zn-3Cu Alloy

The influence of homogenization and quench-aging treatments on the dry sliding friction and wear behavior of Al-40Zn-3Cu bearing alloy was experimentally studied. These treatments removed dendritic structure of the alloy and caused the formation of zinc-rich precipitates distributed homogenously in the matrix of the alloy. It was observed that quench-aging treatment carried out at temperatures of 100 °C and 150 °C significantly improved both hardness and strength of the alloy as compared to homogenization treatment. However, aging at 200 °C lowered these values of the alloy but increased its elongation. Dry sliding wear test results displayed that homogenization and quench-aging treatments increased the wear performance of the alloy. However, it is found that the quench-aging treatment created more powerful effect for improving wear performance of the alloy than homogenization. Quench-aging treatment at 100 °C for 300 min resulted in a decrease in the lowest specific wear rate of the alloy by causing the highest increases in its hardness (from 119 HB to 178 HB), yield strength (from 288 MPa to 383 MPa) and tensile strength (from 319 MPa to 407 MPa) due to the age hardening mechanism. It was observed that the worn surfaces of the alloy samples were composed of adhered and smeared material and delaminated areas. This observation suggested that adhesion and delamination were the operative wear mechanisms of the alloy. The results were explained and discussed in terms of microstructural features, mechanical properties, and wear mechanisms of Al-40Zn-3Cu alloy.

Mechanical characteristics and optimization of wear parameters of hybrid (TiO2 + Y2O3) nanoparticles with Al matrix using squeeze casting technique

Purpose The purpose of this paper is to examine the mechanical characteristics and optimization of wear parameters of hybrid (TiO2 + Y2O3) nanoparticles with Al matrix using squeeze casting technique. Design/methodology/approach The hybrid aluminium matrix nanocomposites (HAMNCs) were fabricated with varying concentrations of titanium oxide (TiO2) and yttrium oxide (Y2O3), from 2.5 to 10 Wt.% in 2.5 Wt.% increments. Dry sliding wear test variables were optimized using the Taguchi method. Findings The introduction of hybrid nanoparticles in the aluminium (Al) matrix was evenly distributed in contrast to the base matrix. HAMNC6 (5 Wt.% TiO2 + 5 Wt.% Y2O3) reported the maximum enhancement in mechanical properties (tensile strength, flexural strength, impact strength and density) and decrease in porosity% and elongation% among other HAMNCs. The results showed that the optimal combination of parameters to achieve the lowest wear rate was A3B3C1, or 15 N load, 1.5 m/s sliding velocity and 200 m sliding distance. The sliding distance showed the greatest effect on the dry sliding wear rate of HAMNC6 followed by applied load and sliding velocity. The fractured surfaces of the tensile sample showed traces of cracking as well as substantial craters with fine dimples and the wear worn surfaces were caused by abrasion, cracks and delamination of HAMNC6. Originality/value Squeeze-cast Al-reinforced hybrid (TiO2+Y2O3) nanoparticles have been investigated for their impact on mechanical properties and optimization of wear parameters.

Sliding Wear Response of Marble Dust Coatings on Mild Steel Substrates

Reusing and organizing industrial solid waste not only tackles the problem of rising environmental contamination but also lowers landfill space. Furthermore, repurposing these wastes for certain possible uses lowers material costs and production costs. Consequently, the research focuses on the repurposing of marble dust, a by-product of ornamental stone processing, for use as a coating material on metal substrates. A well-designed high-velocity oxy-fuel spray coating equipment is used to deposit the material. In accordance with ASTM G 99-05, high-temperature sliding wear tests are performed on the depositions of coatings using a tribometer, incorporating Taguchi’s L16 orthogonal array. Control variables with a substantial influence on wear loss are discovered, and an ideal factor setting is determined based on the least wear loss. The morphologies of worn surfaces are studied to identify probable wear processes. Based on the outcome of parametric analysis, experiments are conducted using a diverse set of recognized significant control factors, while maintaining consistency in the other variables, to enhance the accuracy of assessing their individual impacts on the specific wear rate.

Effects of dispersed α-Al2O3 particles into a cold-sprayed aluminium coating on its subsequent oxidation by the PEO process

The present study focused on the use of a duplex surface treatment combining cold-spray deposition and plasma electrolytic oxidation (PEO) to produce an aluminium metal matrix composite coating, including dispersed α-Al2O3 particles, with improved tribological properties. Al/α-Al2O3 composite coatings were first deposited by cold-spray, with various thickness and proportion in α-Al2O3 particles, and, then partially oxidized by PEO under various processing durations and sparking regimes (arcs or soft regime). The feasibility of cold-spraying thick, compact and adherent aluminium coatings containing well-dispersed α-Al2O3 particles (up to 14 vol%) was demonstrated in this work. It was also pointed out that the addition of hard α-Al2O3 particles into the spray composition tends to densify the deposited aluminium coating. This was related to a stronger peening effect which, in turn, decreases the growth kinetic of the subsequent PEO oxide layer. The presence of dispersed α-Al2O3 particles was found to promote the formation of the corundum alumina phase in the PEO oxide layer by triggering the transition to the soft sparking regime earlier. It was also observed that dispersed α-Al2O3 particles remain unaffected throughout the PEO oxide layers formed within the conventional arcs sparking regime while they undergo a morphological transformation within the specific soft sparking regime. This was explained by considering the different type of micro-discharges that initiate during each regime. Finally, sliding wear tests revealed that the incorporation of α-Al2O3 particles into the cold-sprayed coating resulted in a slight decrease in the friction coefficient and the wear rate of the produced PEO layers.

Effects of low-power laser hardening on the mechanical and metallurgical properties of biocompatible SAE 420 steel

The present experimental work is carried out on SAE 420 steel to optimize process parameters of low-power laser hardening to improve surface micro-hardness and wear resistance for dry sliding for bio-medical applications. Laser power is the most significant factor for micro-hardening and wear resistance. Rank two for scanning speed and three for standoff distance, respectively. The experiments show that the surface micro-hardness of treated samples varies from 711 to 833 Vickers Pyramid Number by optimized process parameters such as laser beam power of 300 W, laser scan speed of 1.0 mm/s, and standoff distance of 225 mm. In comparison, the base material micro-hardness is 208 Vickers Pyramid Number as the predictive equation generated for finding micro-hardness value for the above three laser hardening process parameters. The dry sliding wear test is conducted on all laser-treated samples and a comparison is made with the untreated sample. A significant improvement in wear resistance was observed for treated as compared to untreated samples. The wear of laser hardened sample of SAE 420 steel was 3.67 x10-9 g/cm compared to untreated base metal wear rate of 139.00 x 10-9 g/cm at an applied load of 30 N and sliding speed of 300 revolutions per minute. The scanning electron microscopy analysis of wear samples (untreated, treated maximum, and minimum hardness) is observed for investigating material removal patterns.

Structural integrity of glass fiber reinforced nanocomposites under hydrothermal aging for offshore structure applications

Glass fiber composites are widely used in offshore structures for marine application due to their exceptional strength-to-weight ratio, corrosion resistance, and durability. As offshore structures are exposed to harsh environmental conditions, including saltwater, fluctuating temperatures, and hydrothermal influences, understanding the effects of aging on structural integrity on glass fiber composites becomes very important. In this study glass fiber-reinforced epoxy nanocomposites with 1 % and 2 % nano Al2O3 reinforcement were produced using the vacuum-assisted resin transfer molding. These composites were subjected to a three-month aging process in artificial seawater at a temperature of 70 °C. Mechanical properties were assessed through Tensile and Flexural Tests, while thermal properties were analyzed via TGA, DTA, and DSC analysis. To examine the structural characteristics, Fourier Transform Infrared (FT-IR) spectrophotometry was utilized, and SEM analysis was conducted. Wear properties were evaluated through dry sliding wear tests. Water absorption properties were determined in a precisely controlled seawater bath. The findings reveal that the incorporation of 1 % nano Al2O3 effectively diminishes the water absorption rate, thereby safeguarding the mechanical, thermal, and structural properties within a hydrothermal environment.

Effect of W on the Mechanical Properties and Tribological Behavior of CoCrFeNiWx Compositionally Complex Alloy

Introducing the hard second phase into soft matrix and reducing the grain size are key strategies to enhance the strength and wear performance of metallic alloys. Herein, to investigate the effect of hard second phase on the mechanical properties and tribological behavior of face‐centered‐cubic (FCC) CoCrFeNi compositionally complex alloy (CCA), a series of ultrafine‐grained CoCrFeNiWx (x = 0, 0.3, 0.5, and 1.0) CCAs with varying W contents are fabricated. The results show that the single FCC CCA transforms to the dual phase of FCC and μ phase after addition of W. With increasing W content, the hardness and yield strength show a linear increase due to the additional solid solution strengthening and secondary phase strengthening, but the fracture strain shows an opposite trend. Dry sliding wear tests show that both coefficients of friction and wear rates decrease with the W content. The wear mode changes from abrasive wear for CoCrFeNi CCA to multiple wear modes of abrasive wear, oxidative wear, and fatigue wear for W‐containing CCAs. These results suggest that adding W into the FCC CCA matrix could strengthen the FCC alloy and simultaneously improve wear performance.

Wear behavior of HVOF sprayed cobalt-based composite coatings reinforced with Cr3C2

Metal matrix composites are widely used to improve the wear resistance of materials, and, among these composites, WC-Co and Cr3C2-NiCr (metallic binders) are the most common systems used for thermally sprayed applications. On the other hand, metallic coatings such as cobalt-based alloys are also used for high temperature and wear resistant applications. Among the cobalt-based alloys, Stellite-6 shows a transition from severe to mild wear at high temperatures due to a formation of an oxide layer on the surface. However, the reinforcement of cobalt-based alloys (such as Stellite-6) with Cr3C2 particles has not been widely explored. In this research, coatings of Stellite-6 reinforced with Cr3C2 were deposited on steel substrate by high velocity oxygen fuel (HVOF) technology. The tribological behavior of the composite coatings was evaluated at room temperature and 300 °C using reciprocating dry sliding wear tests. A comparative study of microstructure and chemical composition using scanning electron microscopy (SEM) and Raman spectroscopy, as well as wear and hardness testing, were performed to evaluate the effect of carbide content on the tribological behavior of coatings. Based on these results, the wear mechanisms of the coatings are proposed, focusing on the influence of the reinforcement to improve the wear performance of the coatings.

Microstructures and improved properties of Cu–Mo alloys induced by high current pulsed electron beam irradiation

In this paper, a Cu–Mo alloying layer with improved properties was fabricated by high current pulsed electron beam (HCPEB) irradiation. The microstructure of the modified layer was investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness and friction properties were also measured. After HCPEB irradiation, nano Mo particles, solid solution, and long-period superlattice structures were generated on the surface of Cu–Mo alloys, together with the formation of defect structures. These microstructures led to a significant increase in the surface hardness. The results of sliding wear tests indicated that the HCPEB-irradiated samples exhibited better properties compared with the initial one, which was attributed to the ultrafine Mo particles and the hardened surface.