Hardness Enhancement Research Articles

Effects of milling time and sintering temperature on the mechanical properties of 8 wt% WC/AlCoCrFeNiTi0.5 high entropy alloy matrix composite

The present study investigates the effect of milling time, and sintering temperature on the microstructure and mechanical properties of the spark plasma sintered 8 wt% WC/AlCoCrFeNiTi0.5 high entropy alloys matrix composite (HEAC). The results show that the grain size is decreased first and then increased with an increase of milling time. The refined grain along with the homogeneous distribution of reinforcements is observed when milling for 15 h. It also shows both of relative density and compression strength of compacts are increased first and then decreased with an increase of sintering temperature. A highest relative density of 99.89 % and a fracture strength of 2683 MPa are obtained at 1150 °C. Another, sintering leads to crystal structure transition from BCC to FCC for the solid solution phase. The formation of (Fe, Co)6W6C complex carbide as a main strengthening phase is conducive to the enhancement of hardness. The strengthening mechanism is mainly attributed to dislocation strengthening and Orowan mechanism.

Chemical and mechanochemical degradations of ultrafast laser surface structured Ti6Al4V in simulated body fluid environment

In the present study, the effect of ultrafast laser surface structuring of Ti6Al4V (using a Ti: Sapphire laser with a pulse duration of 100 fs and 3000 fs) on its surface topography, nanomechanical properties, tribocorrosion property, and bioactivity has been undertaken. Surface structuring leads to defect-free periodic surface structures with shockwave-induced compressive residual stresses and grain refinement (subgrain size of 5.2 µm) as compared to as received Ti6Al4V (26 µm). There is a significant enhancement in nano hardness (5600–5800 MPa) and Young's modulus (139 – 148 GPa) as compared to as received Ti6Al4V ((nano hardness of 3800 MPa), (Young's modulus of 117 GPa)) due to laser surface structuring. The tribocorrosion kinetics were significantly reduced in laser surface structured Ti6Al4V as compared to as received one. The individual influence of tribocorrosion property was established. A detailed microstructural study and immersion studies showed the presence of a higher fraction of calcium phosphate deposition in surface-structured samples (0.0432–0.0461 mg/cm2 after 7 days) as compared to as received Ti6Al4V (0.018 mg/cm2 after 7 days). The presence of hydroxyapatite has been confirmed by X-ray photoelectron spectroscopic analysis.

INFLUENCE OF NICKEL ON THE MICROSTRUCTURAL EVOLUTION AND MECHANICAL PROPERTIES OF LM6-ALLOY-BASED FUNCTIONALLY GRADED COMPOSITE TUBES

Despite the growing demand for new materials, we used the horizontal centrifugal casting technique to synthesize functionally graded composite (FGC) tubes using an LM6 alloy containing (3, 6 and 9) w/% nickel. All the fabricated tubes were evaluated for variations in microstructure, hardness and tensile properties along the radial cross-section in three distinct zones (inner, transition and outer). X-Ray diffraction (XRD) results indicated the formation of in-situ Al3Ni in all FGC tubes, and these in-situ tri-aluminides increased further with the addition of Ni. A comprehensive microstructural analysis across the tubes utilising scanning electron microscopy (SEM) images showed that gathering in-situ Al3Ni particles keeps growing nearer the outer zone, and primary Si cuboids increase in the inner zone. This accumulation of particles improved the mechanical properties at all three zones of the FGC tubes compared to the LM6 tube having no nickel. The results of the hardness investigation showed that precipitated Al3Ni in FGCs has a beneficial impact on the enhancement of hardness. Furthermore, the observed UTS improvement in the FGC tubes was clearly associated with the precipitation and strengthening action of Al3Ni intermetallic phases, while a significant reduction in elongation has been noted. Due to the influence of centrifugal force and density variation, the tube containing 9 w/% of Ni demonstrated good gradation among composite alloy-fabricated FGC tubes, with in-situ Al3Ni particles settling largely in the outer zone and primary Si particles settling primarily in the inner zone across the radial thickness.

Phase equilibria, thermodynamic assessment, and the mechanical property of B2 phase of the Al-Ga-Ni ternary system

Ni-based alloys, known for their exceptional mechanical properties and high corrosion resistance in harsh environments, are extensively utilized in gas-turbine engines for propulsion and energy generation. Of particular interests are the L12-Ni3Al and B2-NiAl phases in Al-Ni alloy, which can be the strengthening phases for superalloy and high temperature structural materials, respectively. After Ga addition in the Al-Ni system, these promising intermetallic compounds form a continuous compositional range encompassing the L12-Ni3(Al, Ga) and B2-Ni(Al, Ga) phases. They exhibited distinct mechanical properties contingent on the ratio of Al to Ga. Additionally, Ni and Al are the commonly used substrates in the electronic package and Ga has been used as a filler material for interconnection. Hence, the Al-Ga-Ni phase equilibria are of practical importance for designing L12-Ni3(Al, Ga) and/or B2-Ni(Al, Ga) phase-dispersed Ni-based alloys as well as for evaluating interfacial reactions in the Al/Ga/Ni contacts. However, the Al-Ga-Ni ternary system remains relatively unexplored. In this study, Al-Ga-Ni isothermal sections at 600 (Ni-lean), 900, and 1000 (Ni-rich) °C were experimentally constructed based on equilibrated alloys. Additionally, a CALPHAD-type thermodynamic assessment for the Al-Ga-Ni ternary system was comprehensively performed based on all available experimental information. Furthermore, the Young's modulus and hardness of four B2-Al(Ga, Ni) compounds were determined, revealing that the addition of Ga to B2-NiAl phase would lead to a significant decrease in Young's modulus but a notable enhancement in hardness.

Revealing the role of λ-carrageenan on the enhancement of gel-related properties of acid-induced soy protein isolate/λ-carrageenan system

This work explored the pivotal role of λ-carrageenan in fortifying the gel structure, consequently enhancing gel-related attributes within an acid-induced soy protein isolate/λ-carrageenan system (SPI/Car). The model system was prepared by subjecting a thermally treated mixture of these two biopolymers to acidification. Small-angle X-ray scattering (SAXS) and chemical force analysis unveiled the profound influence of hydrogen bonding and electrostatic interactions in the formation of the intricate network architecture of SPI/Car gels. Remarkably, λ-carrageenan interacted with the hydrophilic groups on the surface of agglomerated SPI particles, effectively composing the fundamental framework of SPI/Car gels. Simultaneously, λ-carrageenan emerged as a linchpin through hydrogen bonding, establishing pivotal crosslinking connections. The introduction of λ-carrageenan resulted in a reduction in SPI particle size, the dispersion of previously formed aggregates, and a subtle blurring of the SPI particles. It also significantly heightened the prevalence of hydrogen bonding and electrostatic interactions, ultimately giving rise to a robust yet somewhat coarse gel structure, as evidenced by confocal laser scanning microscopy (CLSM). These profound structural alterations underpinned the enhancement of water-holding capacity (WHC) and gel hardness in SPI/Car gels. These findings hold promise for the rational design and application of SPI-based systems in the production of processed vegetarian and vegan foods.

Investigation of the structural, mechanical, radiation and neutron shielding properties of the TeO2-B2O3-Li2O-MoO3-CuO glass system

In this study, the structural, mechanical, radiation and neutron shielding properties of (78-x)(0.4TeO2-0.6B2O3)− 20Li2O-xMoO3-2CuO glass system, were investigated. A variety of characterisation methods, including optical absorption spectroscopy, FTIR, EPR, and X-ray diffraction, were used to examine the structural characteristics. Molecular orbital coefficients were calculated from EPR and optical absorption measurements. EPR lines of both Cu2+ and Mo5+ ions were observed in the EPR spectra. The mechanical properties were assessed through experimental measurements, while the elastic properties were evaluated using the semi-empirical approaches of the Makishima and Mackenzie model, along with the bond compression model. The inclusion of 4% MoO3 led to noteworthy enhancements in both hardness and fracture toughness. Hardness increased from 4.364 to 4.664 GPa, and fracture toughness improved from 0.980 to 1.226 MPa.m1/2. The mass attenuation coefficients (MAC), mean free paths (MFP), half-value layers (HVL), and effective atomic numbers (Zeff) were measured in the energy range of 59.54–661.62 keV. The measurement of equivalent dose rates resulting from the absorption of fast neutrons was conducted utilizing a 241Am-Be fast neutron source with an activity of 10 mCi. The exposure buildup factor (EBF) and the fast neutron removal cross section (ΣR) were therotically calculated. The potential suitability of glasses for nuclear security applications was assessed by evaluating their proton and alpha shielding properties. The study found that glasses containing higher amounts of TeO2 and MoO3, within the TeO2-B2O3-Li2O-MoO3-CuO composition, demonstrated enhanced capabilities for shielding against radiation and neutrons.

Hardness enhancement by laser modification of titanium under an auxiliary graphite layer

Hardness enhancement by laser modification of titanium under an auxiliary graphite layer

The Effect of Rotational Tool Speed on Dissimilar Joint Aluminum-Copper Plate Friction Stir Welded Joint

The study investigates the impact of rotational tool speed on the mechanical properties and microstructure of aluminum-cooper friction stir-welded joints. It found that higher rotational speed leads to increased grain size, possibly due to increased heat production. Higher hardness values in the stir zone result from uniform dispersion of smaller copper particles. The study found that 540 rpm yields the maximum hardness value in the stir zone, measuring 67 VHN. However, higher speed results in defects like voids, cracks, and intermetallic compounds (IMCs), which are linked to the formation of IMCs at elevated temperatures. The optimal welding conditions at 550 rpm balance grain refinement, hardness enhancement, and defect mitigation, contributing to the understanding of welding process parameters.

Biocompatible organic coating fabrication via polymer/clay nanocomposites: Evaluation of mechanical improvements

AbstractThis study focuses on achieving mechanical enhancements in biocompatible organic coatings. A solvent‐based method is employed to produce biocompatible nanocomposites using polyvinylpyrrolidone (PVP) and bentonite nanoclays (BNT) as constituents to achieve this objective. Subsequently, the nanocomposites are spin‐coated onto a glass substrate, resulting in smooth and defect‐free films with a thickness of 5 μm. Through instrumented‐indentation testing, it is observed that BNT reinforcement leads to significant improvements in mechanical properties. Specifically, the addition of 0.5, 1, and 5 wt% of BNT in PVP results in enhancements of 105%, 77%, and 430% in elastic modulus, respectively, while hardness is improved by 166%, 211%, and 448%, respectively. The considerable improvements in the composite modulus cannot be adequately explained by assuming perfect adhesion between the constituents of the composite (as suggested by the Halpin–Tsai model) or by considering the contributions from the interface/network of silicate layers (as proposed by the Modified Halpin–Tsai model). Instead, the significant enhancements in hardness and modulus values are primarily attributed to a notable increase in the BNT volume fraction, ranging from 4 to 9 times, occurring under the Berkovich tip due to the aggregated silicate layers. The findings highlight the role of aggregated silicate layers in enhancing both hardness and modulus and contribute to the development of advanced biocompatible coatings with improved mechanical properties.Highlights Enhanced mechanical properties in biocompatible coatings. Biocompatible nanocomposites of polyvinylpyrrolidone (PVP) and bentonite nanoclays (BNT). Spin‐coated nanocomposite films on glass: smooth, defect‐free, 5 μm thick. BNT reinforcement boosts elastic modulus and hardness of PVP. Aggregated silicate layers under compression drive substantial mechanical improvements.

Enhanced properties of nanocrystalline alumina ceramic with compressive prestress and coherently aligned nanograins

AbstractPrestress strategy is effective to inhibit crack advancement and toughen structural materials such as concrete and glass. However, it is difficult to be utilized in ceramic because of the solid‐state processing. In this work, nanocrystalline alumina ceramic with high compressive prestress and coherently aligned nanograins were successfully prepared by the ultra‐high pressure sintering technology. The as‐prepared ceramics exhibited remarkably enhanced mechanical properties, including hardness of 25.9 GPa and fracture toughness of 3.2 MPa·m1/2, which were respectively 36% and 51% higher than corresponding parameters of sapphire. Ultra‐high pressure generated compressive prestress as large as several hundred megapascal, and coherent nanograins in the dimensions of 10–15 nm, which markedly contributed to the simultaneously enhancement in toughness and hardness for ceramic materials. The prestressing strategy provides a new opportunity for fabricating advanced ceramics with high failure resistance.

Effect of Laser Surface Texturing on Schmid Factor and Plastic Deformation Mechanisms on AISI 301LN Steel

In this comprehensive study, the multifaceted impact of laser surface texturing (LST) on AISI 301LN stainless steel is explored. Changes in the microstructure, mechanical properties, and grain characteristics are examined. The dynamic relationship between Schmid factor evolution and plastic deformation in this stainless steel alloy is unveiled through the analysis of grain statistics and individual grain scrutiny. It is revealed that LST initiates the formation of strain-induced α’-martensite, grain refinement, and substantial hardness enhancements. Notably, an α’-martensite crystalline size of 2.05 Å is induced by LST. Furthermore, a 12% increase in tensile strength is observed after LST along with an 11% boost in yield strength. However, reductions of 19% in elongation to fracture and 12% in the area reduction are experienced.

Microstructure, mechanical properties and thermal stability of Cr/WC nano-multilayered coating synthesized by ion beam sputtering

Cr/WC nano-multilayered coatings with fixed period ratio (Cr:WC=1:2) were synthesized by using ion beam sputtering method. The microstructure, mechanical properties and the thermal stability of coatings were investigated by X-ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and nanoindentation. Well-defined laminar amorphous microstructure and uniform monolayers, which consists of amorphous WC1-x and Cr, can be found in the as-deposited nano-multilayered coatings with series modulation period. Although the hardness of Cr/WC nano-multilayered coating increases with the increasing of modulation period, it is still lower than the value predicted by Hill model. Almost all the toughness of Cr/WC nano-multilayered coatings are lower than that of monolayer Cr coating, however, they are higher than that of monolayer WC coating, indicating that the addition of Cr and nano-multilayered architecture can improve the toughness of monolayer WC coating. Both microstructure and mechanical properties of Cr/WC nano-multilayered coatings were stable when the vacuum heat treatment temperature was lower than 400 °C. As the heat treatment temperature was 600 °C, some nanocrystalline W2C, W and WC1-x were enclosed in the amorphous WC sublayer which is beneficial to its hardness enhancement while it is harmful to its toughness. As the heat treatment temperature was 800 °C, the nano-multilayered structure was destroyed completely and its mechanical properties were seriously degraded.

Tolerance to the proton irradiation of the Gd3AlxGa5-xO12 (x = 0,1,2,3) scintillation crystals for future collider experiments

The studies of the influence of proton irradiation on the optical properties of the undoped Gd3AlxGa5-xO12 (x = 0,1,2,3) single crystals were carried out. A set of induced absorption bands have been detected, which are most pronounced in Gd3Ga5O12. The origin of the bands is discussed. It is shown that the intensity of the induced absorption bands gradually decreases and no additional bands appear as gallium is replaced by aluminum. The conclusion on the enhancement of the radiation hardness of Gd3AlxGa5-xO12 with the substitution of Ga cations with Al is done.

The effects of solution heat treatment on the microstructure and hardness of an aluminum-4% copper alloy with added nickel and tin

This study delves into the investigation of intermetallic compounds, specifically Al3Ni, Al3Sn, Al2Cu, Ni3Al, and their formation during the alloying additions and heat treatment procedures of Al-4%Cu alloy with the addition of Ni and Sn. After manufacturing, an extensive range of tests, encompassing hardness assessments, SEM and XRD analysis, and optical microscopy, were executed. The introduction of Nickel (Ni) and Tin (Sn) into the base alloy resulted in a gradual and significant enhancement in hardness, with Alloy 3 exhibiting the most remarkable improvement, showcasing a 214.18 % increase in hardness attributed to higher concentrations of Ni and Sn. Then, heat treatment was carried out that encompassed an initial homogenization phase at 400 °C for a duration of 8 h, followed by precise water quenching. Subsequently, controlled aging precipitation was conducted at 150 °C with distinct time intervals. Comparative analyses of the effect of heat treatment on the hardness values revealed substantial improvements whereas base alloy showed a 67.55 % improvement after the heat treatment. On the other hand, Alloy 1, Alloy 2, and Alloy 3 indicated a 73.26 %, 36.03 %, and 31.22 % enhancement of hardness values respectively. The heat treatment process aimed to meticulously explore the intricate influences of Ni and Sn on the age-hardening process, with specific consideration to identifying the optimal aging time. The incorporation of Ni and Sn into the alloys led to the formation of intermetallic compounds, effectively impeding dislocation movement. Remarkably, Alloy 1 with lower Ni and Sn contents exhibited the most favorable response to the heat treatment, demonstrating a substantial 73.26 % increase in hardness at the optimal aging time. SEM images unveiled the formation of finer precipitates resulting from the aging treatment. This study offers valuable insights into the impact of alloying additions and heat treatment on the microstructure and hardness properties of Al-4%Cu alloys, with potential implications in the fabrication of advanced materials.

Unveiling microstructural evolution and enhanced wear resistance of Co37Cr28Ni31Al2Ti2 multicomponent alloy via high-carbon addition

As a representative multicomponent alloy (MA) system, CoCrNi MAs and their derivatives have shown good strength-ductility combinations but the friction behaviors have been less studied. In this work, the influence of high-carbon addition on the microstructure, (nano)hardness, and wear behavior of the Co37Cr28Ni31Al2Ti2 MA are investigated in detail. Different from the face-centered-cubic (FCC) solid solution and ordered L12 precipitates in the base alloy, massive orthorhombic (Cr,Co,Ni)7C3 and FCC (Cr0.2Ti0.8)C particles together with some long-strip-shaped graphite-3R crystals appear in the L12-strengthened FCC matrix for the high-carbon-bearing sample, resulting in an enhancement of hardness from 292 ± 11 HV to 581 ± 29 HV. Moreover, the wear rates (WRs) and the friction coefficients (COFs) under dry sliding conditions for the base alloy are measured to be ∼9.55 × 10−5 mm3/N∙m and ∼0.6, and ∼6.02 × 10−4 mm3/N∙m and ∼0.8, respectively, at loads of 2 N and 10 N. After adding carbon, the wear resistance is significantly improved (average WR: ∼2.81 × 10−6 mm3/N∙m and ∼1.89 × 10−5 mm3/N∙m; average COF: ∼0.5 and ∼0.7 at loads of 2 N and 10 N). This improvement surpasses similar compositions prepared by casting and is comparable to surface-treated MAs. During friction and wear experiments, the fracture and detachment of hard carbides introduce additional abrasive particles into the tribosystem, resulting in a transformation from adhesive wear-dominated to abrasive wear-dominated. The wear resistance enhancement and friction mechanism transformation are further evidenced by the surface morphologies of the alumina counterbody materials after friction. The present findings indicate that the in-situ formation of carbides should be a promising strategy to enhance the wear resistance of MAs.

Effect of bainitic and retained austenite's length scale on the aqueous corrosion behaviour of nanostructured bainite in 3.5 wt% NaCl

Microstructural refinement offers immense advantages in terms of enhancement of strength, hardness and wear resistance in carbide-free bainitic steels. Lath thickness in bainite can be changed while maintaining the similar volume fractions of bainitic ferrite (BF) and retained austenite (RA) by modifying the grain size of austenite by changing the austenitizing temperature. However, the effect of this microstructural refinement on the corrosion response is difficult to predict and has not been studied. Hence, the current study aims to study the corrosion response of carbide-free bainitic steels formed by austenitization at 900°C (NSB_900) and 1000°C (NSB_1000) respectively and austempered at 250°C. Finer BF lath thickness and RA was obtained in NSB_1000 while the volume fractions of both BF and RA were the same in both the blocks of steels. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) technique have been used to evaluate the corrosion behaviour of the two steel blocks. Lower corrosion current density was found for NSB_1000 which had a finer microstructure although corrosion potential was similar for both the specimens due to similar bainitic volume fraction. The side-section SEM of NSB_1000 showed a thinner corroded layer and the top surface showed a better connected and adhered corrosion film as compared to NSB_900 which showed the corroded layer as disconnected patches leading to a significant part of the sample still being exposed to subsequent corrosion. This manifested in NSB_1000 showing higher polarisation resistance, solution resistance, charge transfer resistance and higher tendency towards an ideal capacitive behaviour.

Strengthening phase and mechanical property analysis of artificially aged Al7075 – Ni coated Al2024 composites

This technical paper demonstrates the possibilities of nickel (Ni) coated Al2024 powder reinforcement in an Al7075 matrix using the liquid stir casting technique. Additionally, the paper focuses on achieving stable properties by implementing artificial aging heat treatment. To apply the Ni coating, the electroless nickel plating technique was utilized, and a minimum coating thickness of 8 μm was determined to effectively prevent the dissolution of Al2024 powder reinforcements within the Al7075 matrix. Stir casting facilitated the uniform dispersion of the coated Al2024 powder up to a weight percentage of 7%. Subsequently, the Al7075 alloy and composites underwent artificial aging through solution heat treatment (SHT) at 450 °C for 4 h, followed by water quenching and aging at temperatures of 120, 150, and 180 °C. Aging at 120 °C was found to yield superior results compared to aging at 150 and 180 °C, thus identified as the optimum aging temperature. When the Ni coating thickness was increased beyond the optimal 8 μm, the resulting enhancements in hardness for both as-cast and peak-aged specimens, as well as the tensile strength, were not significant. The improvements observed were only marginal, ranging between 2 to 3%. Fracture surface analysis revealed that the predominant fracture mode in the Al7075 alloy was ductile, characterized by dimple rupture. In the as-cast Al7075-(7%, 8 μm) Al2024 composite, a mixed fracture mode comprising both brittle and ductile characteristics was observed. In the peak-aged (120 °C) Al7075-(7%, 8 μm)Al2024 composite, the overall fracture mode exhibited a dominant brittle nature. Analytical techniques including XRD, TEM, and EDS confirmed the presence of Mg2Si, MgZn2, CuAl2, and CuAl2Mg phases in the peak-aged (120 °C) Al7075-(7%, 8 μm) Al2024 composite. These phases contributed to the enhancement of the properties of both the Al7075 alloy and its composites. The developed composites can be used in automobile parts and aerospace applications.

Enhancing Tribo-Mechanical and Corrosion Properties of ADC 12 Alloy Composites through Marble Dust Reinforcement by Squeeze Casting Technique.

This research intends to enhance the tribo-mechanical and corrosion properties of ADC 12 alloys by incorporating marble dust (MD) as a reinforcing element. Composites with varied MD concentrations (0-10 wt%) were fabricated using a squeeze casting process, addressing the limitations of conventional casting techniques. The microstructural analysis confirmed homogeneous MD dispersion within the ADC 12 matrix, facilitating an effective load transfer and solid interfacial bonding. As MD content increased, the experimental density decreased, while porosity increased from 1.22% to 3.97%. Remarkably, adding 4 wt% MD yielded a 20.41%, 17.63%, and 15.75% enhancement in hardness, tensile, and compression strength compared to the as-cast ADC 12. Incorporating MD particles facilitated Orowan strengthening and Hall-Petch strengthening mechanisms, contributing to the observed improvements. The wear rate was reduced by 18.33% with MD content, showing a 17.57% corrosion reduction at 72 h. These outcomes establish the synergistic benefits of ADC 12 squeeze casting with MD reinforcement, delivering superior tribo-mechanical and corrosion properties.

Indentation and sliding contact testing of three laser-textured and PVD-coated cemented carbide tools

A new concept for cemented carbide tools was presented with laser-generated abrasive-like protrusions on their machining surfaces that mimic the surface features of diamond or cubic boron nitride abrasives commonly used on honing tools. In this study, the surface structure on the new tools were protected by three different PVD ceramic hard coatings. All three nitride-based coatings, i.e., TiSiN-AlTiN, TiSiN-AlTiN-CrN and AlTiN-CrN, differed in the adhesion layer and coating structure. The coating-substrate systems were assessed by means of indenting and sliding contact testing in order to find out an appropriate one for the textured tools. Experimental methodology included (1) ‘passive’ Vickers indentation hardness tests, and (2) ‘active’ machining tests. In both cases, the resulting surface integrity was inspected by using FIB/SEM/EDS. It is found that both laser texturing and coating deposition changed the hardness. The tool coated by the two-layer film (TiSiN-AlTiN) achieved the best performance, in terms of both hardness enhancement and damage prevention experienced under both tests. Meanwhile, improvement was much less pronounced by the two-layer (AlTiN-CrN) coated tool. Here, cracks appeared under the Vickers indentations and the film was completely or partially spalled-off at some protrusion tops (cutting fronts), due to the concentrated stress during the machining. Finally, the three-layer coating with the TiSiN on the top (TiSiN-AlTiN-CrN) exhibited an intermediate response, where moderate hardness increase was combined with some wear – although less severe than for AlTiN-CrN film - taking place at critical points, such as cutting fronts.

Influence of TiC Particles on Mechanical and Tribological Characteristics of Advanced Aluminium Matrix Composites Fabricated through Ultrasonic-Assisted Stir Casting

The present investigation highlights the development of high-performance materials in the construction materials industry, with a special focus on the production of aluminium matrix composites (AMCs) containing titanium carbide (TiC) particles. The stir casting method with ultrasonic assistance was employed to enhance the mechanical and tribological properties. ASTM standards were employed to evaluate the influence of TiC particles on density, hardness (VHN), ultimate tensile strength (UTS), and wear resistance at various TiC weight fraction percentages (0.0 wt.%, 2.0 wt.%, 4.0 wt.%, 6.0 wt.%, and 8.0 wt.%). Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis were performed to analyse the microstructural changes and elemental phases present in the synthesised composite. Results revealed that the incorporation of 8 wt.% TiC reinforcement in the metal matrix composites demonstrated significant improvements compared to the base alloy. In particular, a substantial enhancement in hardness by 32%, a notable increase of 68% in UTS, and a significant 80% rise in yield strength were observed when contrasted with the pure aluminium alloy. The tensile fracture analysis of the specimens revealed the presence of dimples, voids, and cracks, suggesting a brittle nature. To assess the wear characteristics of the composites, dry sliding wear experiments were performed using a pin-on-disc wear tester. Incorporation of TiC particles resulted in a lower coefficient of friction than the base alloy, with the lowest friction coefficient being recorded at 0.266 for 6 wt.% TiC, according to the data. FESEM and energy-dispersive X-ray spectroscopy (EDXS) were used to examine the surfaces of the worn pin. Overall, the inclusion of TiC reinforcement particles in the matrix alloy greatly enhanced the wear resistance and friction coefficient of the Al-6TiC composites. Ploughing and adhesion under lower loads and delamination under higher loads were the wear mechanisms observed in the wear test.