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This study investigates the impact of multi-walled carbon nanotubes (MWCNTs) on the microstructure and mechanical properties of Al6061 nanocomposites. The MWCNTs were uniformly dispersed in the aluminum alloy matrix using ultrasonication following cold pressing and sintering in a vacuum. The effect of the sintered temperature on the microstructure and mechanical properties of the nanocomposites was evaluated. The addition of MWCNTs resulted in grain refinement, with the nanocomposites exhibiting smaller and more uniformly distributed grains than the pure Al6061 matrix, particularly at lower sintering temperatures of 580 and 600 °C. The nanocomposites also demonstrated an increase in hardness, with peak values observed at 580 °C, primarily due to the effective dispersion of MWCNTs, which restrict dislocation movement and reinforce grain boundaries. While higher sintering temperatures led to significant grain growth and less uniform hardness distribution, lower temperatures favored finer grain structures and more homogeneous hardness profiles. The results suggest that the optimal sintering temperature for achieving the best balance between microstructure and mechanical properties is 580 °C. However, the study also highlights the need for optimized dispersion techniques to achieve a more uniform distribution of MWCNTs. [ABSTRACT FROM AUTHOR]

This study aims to quantify the effect of process parameters on the anodizing of Al6061 aluminum. To achieve this, studies on layer thickness, the porosity of the anodized surface, electrochemical techniques, X-ray diffraction, grain size estimation, and statistical analysis were conducted for three different atmospheres (without air, air, and oxygen). Parameter levels were established as follows: temperature (30 °C, 45 °C, and 60 °C), time (20 min, 40 min, and 60 min), electrolyte concentration (0.5 M), voltage (9 V), and current intensity (0.600 A). A 33 experimental design (three factors, three levels) was proposed, and mathematical models were obtained using general factorial design. The experimental design was used to determine the three most important variables in the optimal condition. A total of 27 tests were conducted using sulfuric acid electrolytic solutions, of which 12 samples were selected by the factorial design method, which simultaneously evaluates the effects of factors and their interactions in a single experiment. Measurement of porosity and oxide layer thickness was performed using scanning electron microscopy. The purity of the anodic layer formed was characterized using X-ray diffraction techniques with a vertical goniometer X-ray diffractometer. The electrochemical behavior is presented through potentiodynamic polarization curves for the anodic layer. A general factorial design and an analysis of variance (ANOVA) were conducted to establish the significant factors for layer thickness, grain size, and reaction rate. Finally, the best results and their parameters for each response are presented. [ABSTRACT FROM AUTHOR]

The demand for low-density automobile components for lightweight automobiles that have less energy consumption has initiated the production of chassis, wheels, bumpers, brakes, and steering using composite materials. This research aimed to fabricate an Al6061-based hybrid composite for automobile components reinforced with 10 wt% silicon carbide and varying aloe vera and bagasse ashes using the stir-casting method. The effects of the composition of reinforcements on the microstructure, hardness and compressive strength of the hybrid composites were assessed. It was found that an increase in bagasse ash and aloe vera ash contents improved the compressive strength. The hybrid composite with 10 wt% bagasse ash and 11 wt% aloe vera ash demonstrated maximum compressive strength of 376.3 MPa. The highest hardness of 91.6 HV was achieved with the hybrid composite having 10 wt% bagasse ash and 11 wt% aloe vera ash. The hardness value of the hybrid composite was increased by 16.27% when compared to a single reinforced Al6061/SiC composite. It was concluded that adding bagasse and aloe vera ashes greatly increased the hardness and compressive strength of Al6061/SiC composite materials. The findings of this research would be useful for automobile component manufacturers.Article Highlights: A new AMC hybrid composite was produced using stir casting. Hybridization effects of Silicon carbide, Bagasse and Aloe vera ashes are studied. Superior compressive strength and hardness are achieved for automobile components. [ABSTRACT FROM AUTHOR]

Materials that are lightweight with superior strength and improved structural properties have consistently been highly sought after in the aircraft and automobile industries for their superior performance. This study investigates the effect of graphene and boron carbide (B4C) additions on the microstructural & mechanical properties of Al6061 MMCs in fabricated and T6 heat-treated conditions. The powder metallurgy technique is used to fabricate the Al6061 hybrid composites reinforced with different volume fractions. i.e 0.5,1 wt% of graphene and 3,6 wt% of B4C. XRD, Optical microscope, FE-SEM with EDAX mapping, Hardness, and Compression tests were employed to evaluate and characterize the Al6061/Gr/B4C hybrid composites. After the T6 ageing treatment, both hardness and compressive strength were increased to 61.08% and 68.51% compared to base Al6061 matrix alloy. The sample Al6061/0.5% Gr/6%B4C-T6 exhibits the highest hardness value of 91HV and sample Al6061/1%Gr/6%B4C-T6 gives the value of higher compressive strength of 298 MPa. The higher tensile strength was observed in the sample Al6061/0.5%Gr/6%B4C-T6 which is 209.53 MPa with 8.907% elongation. The T6 heat treatment has a significant role in the strength improvement. Whereas increment in graphene has no impact on the tensile strength. The tensile strength of Al6061/0.5%Gr/6%B4C-T6 was improved by 43.56% compared to the base Al6061 alloy.

The development of lightweight and high-strength materials is critical for many industries, including aerospace, automotive, and electronics. Metal matrix composites (MMCs) have shown great promise in meeting these requirements. The structural and physical properties of Al6061 alloy reinforced with hybrid MMCs, including TiB2, SiC, and fly ash (FA), were investigated in this research review. The MMCs investigated were made using the stir-casting process. Their microstructure, structural characteristics, and mechanical features were examined. The inclusion of TiB2 and SiC enhanced the composite’s hardness, tensile strength, and wear resistance, while the addition of FA lowered its density and improved its thermal and corrosion resistance. However, the volume percentage, particle dimension, and arrangement of the reinforcing components all had an effect on the physical characteristics of the composite. Therefore, the optimum combination of the reinforcing materials must be carefully selected to achieve the desired properties. The result of this review provides valuable insights into the development of high-performance MMCs for various industrial applications. [ABSTRACT FROM AUTHOR]

In this study, composite materials with Al6061 alloy matrix and B4C particles reinforcement were produced by hot extrusion process. Fabricated composites were examined for the mechanical and machinability attributes. Al6061 alloy powders (<100 µm) and B4C particles (<10 µm) were mixed with the different weight fraction of B4C (3%, 6%, and 9% by weight) of and then cold pressed under 200 MPa pressure. The cold pressed powder metal block was extruded hot after preheating at 550°C for 1 h. Further, the composites were subjected to T6 aging heat treatment after hot extrusion. Microstructure, density, hardness, tensile strength, and wear properties were examined. The effects of cutting speed and cutting force on the machinability were also investigated. In addition, surface roughness and chips formation were examined. High density (99.6%) values were achieved with the extrusion process. With increasing B4C particles ratio, the hardness and tensile values were increased which was substantiated by the fracture morphology of the tensile specimens. It has been observed that tool smearing was high in the machining of the low-reinforced (3% B4C) composite. The highest cutting force was measured as 236 N at a feed rate of 0.27 mm/rev and a cutting speed of 250 m/min. It has also been observed that the average surface roughness decreased with increasing cutting speed and it increased with increasing feed rate. [ABSTRACT FROM AUTHOR]

The object of this research is the horizontal centrifugal casting process of the Al6061 alloy. Usually, cast products experience some casting defects, so the horizontal centrifugal casting process is applied to reduce the possibility of casting defects arising. In some casting processes, especially in the production of cylindrical specimens, casting defects such as porosity are encountered. Therefore, horizontal centrifugal casting was applied to overcome this problem. The test results show that the average hardness value for aluminum 6061 specimens resulting from centrifugal casting products with water cooling was 73.3 HRE, while the average hardness value for aluminum 6061 specimens resulting from centrifugal casting products without water cooling was 86.4 HRE. The microstructure results show that the grain size of centrifugal casting products with water cooling was 82.5 µm, whereas without water cooling it was 75 µm. Higher hardness values were obtained in specimens without mold cooling, this is because the conductivity in molds without cooling was higher compared to molds that experienced water cooling. The higher the heat conductivity of the mold, the faster the cooling process of the cast product. The casting process using the horizontal centrifugal method can be carried out to produce cylindrical spare parts. [ABSTRACT FROM AUTHOR]

In the field of composite materials, extensive research has been undertaken on aluminum-graphite composites. However, a research gap has been identified regarding the specific influence of nano-sized graphite particles on their fracture toughness. Previous studies have predominantly focused on larger graphite particles or different reinforcement materials, resulting in relatively unexplored effects of nano-graphite particles. This research is deemed critical as it has the potential to generate lightweight, high-strength materials, aligning with the demands of aerospace, automotive, and structural engineering. The primary objective of this study is to investigate how the inclusion of nano-sized graphite particles affects the fracture toughness of aluminum-graphite composites. To achieve this objective, systematic dispersion and incorporation of nano-sized graphite particles into an aluminum matrix will be carried out. Mechanical testing, including fracture toughness assessments, will be conducted to evaluate the performance of the composite materials. Factors such as particle size, distribution, volume fraction, and interfacial bonding will also be characterized within the study. It is anticipated that the presence of nano-sized graphite particles will lead to a significant enhancement of the fracture toughness of the aluminum-graphite nanocomposites. This enhancement is expected to be attributed to crack deflection, tortuosity, altered stress distribution, and increased plastic deformation around cracks.

In this study, we investigate a self-healing 60Pb40Sn reinforced Al6061 alloy's tribological behavior through experimentation, focusing on the influence of different reinforcement concentrations on tribological performance. Cylindrical pins with varying filler concentrations were tested using a pin-on-roller Tribometer to evaluate friction behavior, wear resistance, and fractured surface morphology. The results revealed intriguing findings, including a 5% higher coefficient of friction (COF) for the maximum solder concentration sample at lower loads and speeds. Under higher loads (100 N), the COF increased by approximately 16%. However, the three-hole pin samples consistently exhibited higher weight loss than the two-hole pins. Remarkably, at a 100 N load and extended sliding distances, the three-hole pins showed slightly lower friction values, with a reduced COF of 12%, 16%, and 12% at 53 rpm, 106 rpm, and 160 rpm, respectively. Morphological characterization using Scanning Electron Microscope (SEM), Energy Dispersive Spectrum (EDS), and Elemental Maps revealed the wear mechanism and oxidation on the pins' surfaces, contributing to enhanced wear resistance in this self-healing composite, thus presenting a novel insight into self-healing alloy tribology. [ABSTRACT FROM AUTHOR]

The high-velocity impact of powder particles in cold-spray additively manufactured (CSAM) parts creates intersplat boundaries with regions of high dislocation densities and sub-grain structures. Upon microstructure and mechanical characterization, CSAM Aluminum 6061 showed non-uniformity with spatial variation in the microstructure and mechanical properties, affecting the overall response of the additively manufactured parts. Post-processing treatments are conducted in as-printed samples to improve particle bonding, relieve residual stresses, and improve mechanical properties. In this work, we attempt to implement the effects of grain size and distribution of smaller grains along the intersplat boundaries using the grain size distribution function and powder size information to accurately predict the deformation response of cold-sprayed material using a mean-field viscoplastic self-consistent (VPSC) model. The incorporation of an intersplat boundary term in the VPSC model resulted in a stress–strain response closely matching the experimental findings, preventing the superficially high stresses observed due to Hall–Petch effects from ultra-fine-grain structures. Likewise, the results from the grain analysis showed the combined effects of grain size, orientation, and intersplat mechanisms that captured the stresses experienced and strain accommodated by individual grains. [ABSTRACT FROM AUTHOR]

Wire Electrical Discharge Machining (WEDM) is an electrothermal machining process used to produce complex profiles electrically conductive materials. In this investigation, multiobjective optimization using hybrid approach of Taguchi method (TM) and Principal Component Analysis (PCA) has been performed to find the optimal input process parameters like pulse-on time ( T on ), pulse-off time ( T off ), peak current (I), wire speed (WS) for output parameters, namely, cutting velocity (CV), power consumption (PC), and surface roughness (SR). Three different Aluminum based Metal Matrix Composites (AMMC) were fabricated using three different reinforcements i.e. 10 wt.% Aluminum Oxide (Al2O3), 10 wt.% Silicon Carbide (SiC), and combining 5 wt.% Al2O3 with 5 wt.% SiC through the stir casting process. The experiments were conducted based on the L9 orthogonal array approach of Taguchi methodology and regression equations were developed based on the experimental data for the prediction of output parameters. The results of analysis of variance (ANOVA) shows that WS and I are the two most significant factors for CV of all three developed composites whereas for SR, T on and I play critical role. The optimal results show that for machining of Al6061/Al2O3 and Al6061/SiC optimal input parameters are T on = 5 μ s, T off = 4 μ s, I = 1 A, and WS = 3. 1 2 m/s. For hybrid MMC (Al6061/Al2O3/SiC), optimized input parameters are T on = 5 μ s, T off = 7 μ s, I = 1 A, and WS = 3. 1 2 m/s. At optimal input parameters though the CV decreases by 1.53% the PC and SR decreases by 8.95% and 15.47%, respectively, in case of hybrid composite. The machined surface at optimal input parameters were examined by the Scanning Electron Microscope (SEM). This study will help to identify the input parameters for sustainable machining of AMMC for different reinforcements with WEDM. [ABSTRACT FROM AUTHOR]

This study assesses the efficacy of plasma-sprayed Cr2C3 coatings on AA6061 aluminum alloy in reducing erosion at different angles (30, 60, and 90°). The experimental setup involved maintaining a distance of 80 mm between the components, feeding the powder at a rate of 55 g/min, and applying a current density of 460 amps. Weight loss measurements and surface morphology analyses were performed using scanning electron and confocal microscopy. The findings suggest that the Cr2C3 coating significantly improves erosion resistance when compared to specimens without any coating. The erosion angle had a significant impact on the performance of the coating. The coating experienced the least weight loss at an angle of 30° (28.45 g), followed by increased losses at angles of 60° (30.34 g) and 90° (34.2 g). These findings emphasize the significance of the impact angle in determining the severity of material removal.

The subject matter of this study is to use numerical simulation methods to study the influence of the temperature of particles and substrates on the post-deposition coating during the multi-particle deposition process of cold spray. The goal is to study the temperature of Al6061 particles and the temperature of the substrate, which are factors that have a greater impact on the deposited coating, and to observe the shape of the coating and the temperature distribution of the cross-section of the substrate after deposition. The tasks to be solved are as follows: use Python scripts to model multi-particles, generate and randomly assign positions according to particle size distribution in the Euler domain, and establish a cold spray multi-particle collision model to simulate the process of cold spray deposition. The following methods were used: The influence of temperature and substrate temperature on the deposited coating was studied through a single variable method; the Coupled Eulerian Lagrangian (CEL) method was used to simulate the collision process of cold-sprayed Al6061 multi-particles. The following results were obtained: changing the temperature of Al6061 particles has a more obvious control effect on the porosity of the deposited coating; after particles of different temperatures impact the constant-temperature substrate, the high-temperature area on the surface of the substrate is mainly located at the junction of pits; after the particle temperature reaches 650K, the coating changes after deposition are no longer significant, indicating an optimal temperature range for Al6061 particle deposition; increasing the temperature of the substrate can increase the depth of particle deposition on the substrate; at the same time, it serves as a reference basis for further using the CEL method to predict the porosity of the Al6061 coating. Conclusions. The scientific novelty of the results obtained is as follows: 1) powder preheating can effectively reduce the porosity of Al6061 coating; 2) the CEL method has good robustness and is used to simulate cold spray multi-particle deposition to monitor the porosity of the coating, which cannot be achieved by the SPH and ALE methods.

This study investigates the impact of multi-walled carbon nanotubes (MWCNTs) on the microstructure and mechanical properties of Al6061 nanocomposites. The MWCNTs were uniformly dispersed in the aluminum alloy matrix using ultrasonication following cold pressing and sintering in a vacuum. The effect of the sintered temperature on the microstructure and mechanical properties of the nanocomposites was evaluated. The addition of MWCNTs resulted in grain refinement, with the nanocomposites exhibiting smaller and more uniformly distributed grains than the pure Al6061 matrix, particularly at lower sintering temperatures of 580 and 600 °C. The nanocomposites also demonstrated an increase in hardness, with peak values observed at 580 °C, primarily due to the effective dispersion of MWCNTs, which restrict dislocation movement and reinforce grain boundaries. While higher sintering temperatures led to significant grain growth and less uniform hardness distribution, lower temperatures favored finer grain structures and more homogeneous hardness profiles. The results suggest that the optimal sintering temperature for achieving the best balance between microstructure and mechanical properties is 580 °C. However, the study also highlights the need for optimized dispersion techniques to achieve a more uniform distribution of MWCNTs.

Aluminium alloy composites find most of their applications in various engineering fields owing to their higher specific strength, tailorable wear and corrosion resistance and elevated temperature resistance. Current work is an attempt to determine the mechanical and tribological behaviour of aluminium alloy 6061 (A16061) and in situ titanium diboride (TiB2) composites manufactured by conventional stir casting by varying the reaction temperature and time. A16061–TiB2 composites with 3, 6 and 9% by weight of reinforcements were fabricated and tempered in different media. Those composites were initially analyzed for their ultimate strength and hardness to identify the best composition. Results portrayed that the hardness of composites increased with the content of TiB2 and composites with 9% reinforcements were identified to be better. Composite specimen with higher strength was then subjected to tribological test, and the optimal combination of process parameters, obtained by design of experiments, influencing the tribological behaviour was identified by Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). Results of analysis of variance indicated that TiB2 particles significantly influenced the tribological behaviour of Al6061–TiB2 composites along with the variation in load, sliding velocity and sliding distance. The optimal composite sample was again fabricated with Ni–P-coated TiB2 using electroless process and was subjected to hardness measurement. It was found that Ni–P-coated TiB2 composites further enhanced the hardness of the A16061–TiB2 composites. [ABSTRACT FROM AUTHOR]

To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning (SPDT) by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness. Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg2Si and the scratches on the machined surface mostly come from the iron-containing phase (α-, β-AlFeSi). Moreover, the generated Mg2Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg2Si with the medium size (more than 1 µm and less than 2 µm) in Al6061. [ABSTRACT FROM AUTHOR]

Cold spray is a solid-state deposition technique that improves the performance of part surfaces. Most scholars use the CEL framework to simulate the deposition of single particles on the substrate; Single particle depositions cannot fully characterize coating conditions. This article proposes to use the CEL method to simulate the deposition process of cold spray multi-particles on the Al6061 substrate. A multi-particle wrapped model is nested in a deposition model created by CEL to simulate the cold spray multi-particle deposition process. The Euler-Lagrangian method has the characteristics of high accuracy and robustness, and was selected as the method for multi-particle deposition model simulation; The CEL framework is a feasible method to simulate the actual cold spray multi-particle deposition process. The results show that the CEL framework can simulate the deposition of cold sprayed Al6061 multiparticles on the Al6061 substrate, observe the EVF Void value of the coating, and monitor the porosity of the coating after deposition. It is observed that the maximum substrate surface temperature after deposition is 528.2K and is located at the junction of particle and particle impact; By analyzing the temperature change curve of five points collected on the substrate over time, the curve appears multiple inflection points, indicating that heat transfer occurs between the particles and the substrate during the deposition process; the substrate first heats up and then cools down. During the multi-deposition process, the particles undergo plastic deformation and continuously squeeze the coating, thereby achieving interconnection between the particles and the substrate; Mechanical interlocking between particles forms a coating. [ABSTRACT FROM AUTHOR]

In deep rolling, ball and roller type burnishing tools are generally used. It is generally difficult to deep roll contours with curved and conical shapes with the existing rolling tools. The aim of this study is to design experiments with a roller insert that will be an alternative to deep rolling inserts being used now and that can be fixed on the present tool holders; and to investigate the usability of them including curve and conical formed workpieces with the help of this designed tool. For this purpose, a spherical insert with a radius of 1 mm in the form of WNMG was designed based on the WNMG insert model and used in deep rolling of Al6061-T6 material using different forms and parameters. 143, 330, 495 N rolling force, 0.04, 0.08, 0.12 mm/rev feed and 400, 600, 800 rpm spindle speed were selected as rolling parameters. By examining the microhardness and surface structure of deep-rolled Al6061 parts, the achievability of the results of existing tools in deep rolling was investigated. At the end of the study, it was determined that the new type of rolling tool produced results similar to the existing tools in deep rolling in terms of microhardness and surface morphology, which enabled that the workpieces with curve and conical forms could also be rolled, and that this rolling tool could be used as an alternative in deep rolling. [ABSTRACT FROM AUTHOR]

Aluminium composites are extensively used in several industries. The production of Metal Matrix Composite (MMCs) with varying wt. % of reinforcement/s leads to enhancement of wear and mechanical behavior properties. In the present work, varying wt. % of TiB2 and constant wt. % of CeO2 particulates were reinforced in Al6061 alloy to manufacture hybrid Al MMCs by Vortex (Stircasting) technique. Developed hybrid MMCs were hotrolled at 515�C of temperature. Hardness of hybrid MMCs was evaluated by using hardness test rig (Vickers). Results revealed that the hardness strength of developed hybrid MMCs increased with increase of the reinforcement content. The rate of wear of developed hybrid MMCs was evaluated by Pin-on-Disc wear test method. Test trials were conducted according to Taguchi technique. L27 array was implemented for evaluation of data. Effect of varying factors on the rate of wear and Coefficient of Friction (COF) was analyzed by applying ANOVA (Analysis of Variance) method. ANOVA outcomes showed that the reinforcement content had a more significant impact on wear behavior and COF of the MMCs. Finally, L27 array outcomes were verified through confirmation experiments. Wear fractography test shows the internal fractured structure of a wear specimen which was studied using a Scanning Electron Microscope (SEM)

The high-velocity impact of powder particles in cold-spray additively manufactured (CSAM) parts creates intersplat boundaries with regions of high dislocation densities and sub-grain structures. Upon microstructure and mechanical characterization, CSAM Aluminum 6061 showed non-uniformity with spatial variation in the microstructure and mechanical properties, affecting the overall response of the additively manufactured parts. Post-processing treatments are conducted in as-printed samples to improve particle bonding, relieve residual stresses, and improve mechanical properties. In this work, we attempt to implement the effects of grain size and distribution of smaller grains along the intersplat boundaries using the grain size distribution function and powder size information to accurately predict the deformation response of cold-sprayed material using a mean-field viscoplastic self-consistent (VPSC) model. The incorporation of an intersplat boundary term in the VPSC model resulted in a stress–strain response closely matching the experimental findings, preventing the superficially high stresses observed due to Hall–Petch effects from ultra-fine-grain structures. Likewise, the results from the grain analysis showed the combined effects of grain size, orientation, and intersplat mechanisms that captured the stresses experienced and strain accommodated by individual grains.

Aluminium composites are extensively used in several industries. The production of Metal Matrix Composite (MMCs) with varying wt. % of reinforcement/s leads to enhancement of wear and mechanical behavior properties. In the present work, varying wt. % of TiB2 and constant wt. % of CeO2 particulates were reinforced in Al6061 alloy to manufacture hybrid Al MMCs by Vortex (Stircasting) technique. Developed hybrid MMCs were hotrolled at 515°C of temperature. Hardness of hybrid MMCs was evaluated by using hardness test rig (Vickers). Results revealed that the hardness strength of developed hybrid MMCs increased with increase of the reinforcement content. The rate of wear of developed hybrid MMCs was evaluated by Pin-on-Disc wear test method. Test trials were conducted according to Taguchi technique. L27 array was implemented for evaluation of data. Effect of varying factors on the rate of wear and Coefficient of Friction (COF) was analyzed by applying ANOVA (Analysis of Variance) method. ANOVA outcomes showed that the reinforcement content had a more significant impact on wear behavior and COF of the MMCs. Finally, L27 array outcomes were verified through confirmation experiments. Wear fractography test shows the internal fractured structure of a wear specimen which was studied using a Scanning Electron Microscope (SEM). [ABSTRACT FROM AUTHOR]

Dual step stir casting method was utilized to develop Al6061 composite reinforced with SiC (micron) and Si3N4 (submicron) particles in varying proportion and weight percentage. A homogeneous and uniform distribution of hybrid reinforcement without significant porosity was observed in the microstructure of the composites. X-ray diffraction (XRD) results manifest that Si3N4 and SiC particles are thermodynamically stable during the processing and no unwanted phases were detected. Elemental mapping was also performed for phase identification. With reference to the base alloy significant improvement was noticed in physical and tribological properties of hybrid composites. Maximum rise in hardness was 54.64%. Abrasive wear test results from pin on disc reveals that wear resistance get enhanced for all composition and load is found to be most dominating factor affecting wear behavior. [ABSTRACT FROM AUTHOR]

Metal matrix composites are becoming more common in industrial applications due to their superior tribological and mechanical properties. In this work, titanium diboride (TiB2) particles with different weight percentages (1, 3 and 5%) were added to Al6061 using a stir-casting process. The hardness, tensile strength, and wear of Al6061-TiB2 composites were investigated. Each experiment was repeated three times to ensure repeatability, and an average was taken. In addition, an optical microscope and a scanning electron microscope were used to characterize the Al6061-TiB2 composites. The SEM examination shows that the TiB2 particles are distributed evenly throughout the Al6061 matrix. The results show that the hardness, strength, and wear resistance of Al6061-TiB2 composites increase as the weight percentage of TiB2 is increased. The most interesting thing to come out of the data is that adding a small amount of TiB2 particles increases the hardness of the composites much more than previous research has shown. [ABSTRACT FROM AUTHOR]

The current study focuses on the properties of dry sliding characteristics and impact strength of two different aluminum alloys that were reinforced with 100 nm sized Silicon carbide (SiC) and Aluminum oxide (Al2O3) ceramic particles, for improving the mechanical properties of the final alloy with the mixing materials characteristics. Stir casting method is adopted for fabricating the composites, matrix being Al6061 and Al7075, utilizing three distinct reinforcement ratios. In order to improve the mechanical properties and increase resistance to wear, tear, and shear, SiC and Al2O3 are utilized as reinforcing elements. Following the creation of the composite matrices, their physical and mechanical behaviors are examined in accordance with ASTM standards, and a comparison between the hybrid composites made of Al6061 and Al7075 is then completed. Comparison of the obtained samples showed that the Al7075 (12 % SiC + 6 % Al2O3) alloy exhibits characteristics with exceptional tribological and mechanical characteristics. The studied alloy can be used in the automotive industry, for example, in the production of pistons, connecting rods, due to the minimum degree of wear and variable thermal expansion coefficient.

Son yıllarda endüstrinin gelişmesi çevre kirliliğinin artmasında büyük rol oynamıştır. Çevrenin korunması amacıyla özellikle metalik atıkların geri dönüştürülmesi her geçen gün daha fazla dikkat çekmektedir. Bu nedenle özellikle talaş formundaki alüminyum atıklarının düşük enerji ve minimum emisyon ile geri kazanımını sağlayan katı hal yöntemleri tercih edilmeye başlanmıştır. Bu çalışmada, toz metalurjisi ile Al6061 talaşının vakum ortamında (10-4mbar), 30 MPa basınç altında ve farklı sıcaklıklarda (560, 580 ve 600°C), 15 dakika sinterlenerek katı hal geri kazanımları amaçlanmıştır. Sinterleme sıcaklığının malzeme özellikleri üzerindeki etkisinin incelenmesi için üretilen numunelerin Arşimet prensibine göre yoğunlukları ölçülerek, aşınma, sertlik ve eğme testlerine tabi tutulmuştur. Test sonuçları değerlendirildiğinde en yüksek yoğunluk (%97,8) 600°C’de sinterlenen numunede elde edilmiştir. Yoğunluk değerlerinin artış göstermesi mekanik özellikleri de doğrudan etkilemiştir. En yüksek sertlik değeri 58,9 HV ile 600°C’de sinterlenen numunede ölçülmüştür. Artan yoğunluk ve sertlik ile aşınma direncinde artış gözlenmiştir. Eğme testi sonucunda en yüksek eğme mukavemeti 348 MPa ile yine 600°C’de sinterlenen numunede ölçülmüştür. Sonuç olarak sıcak pres yöntemi ile 6061 talaşının katı hal geri kazanımları sağlanmış ve yüksek mukavemetli parça üretiminin mümkün olabileceği ortaya konmuştur.

A hybrid Al6061 composite material was fabricated with various weight percentage of different reinforcing material such as SiC, Al2O3, RHA and ZrSiO4 by liquid metallurgy route via. Stir casting method. The tribological properties were tested and carried out on pin-on-disc tribometers by considering various parameters like, mixture weight percentage of reinforcing materials, sliding distance, speed and applied load to study the tribological characteristics. Taguchi technique was used to analyse the wear rate of hybrid composites. Different experiments were conducted using Taguchi technique and the regression equations were developed through Analysis of Variance (ANOVA) to investigate the influence of various test parameters such as sliding distance, materials parameters (such as weight percentage of reinforcement), sliding distance and applied load. Finally, Taguchi results were used to train the Artificial Neural Network (ANN) model. The input parameters assigned to develop an ANN model are mixture weight percent of reinforcement, sliding distance, sliding speed and applied load. Finally confirmation test was done to verify the predictive model with the experimental results of the wear pin sample. The weight percentage of reinforcement had the greatest influence on statistical and physical properties of hybrid composites while the sliding speed exercised its impact on the Coefficient of Frication (COF) of hybrid composites on dry sliding wear and also on the optimal parameters for less wear rate and low COF. The results indicated that combination of 4.5 wt.% of reinforcement, 30 N load, 0.9 m/s sliding velocity and 3600 m sliding distance was the optimum blend for minimum wear rate and 4.5 wt.% of reinforcement, 3.4 m/s sliding velocity, 3600 m sliding distance and 40 N load was identified as the optimum blend for minimum COF using the main effect plot. [ABSTRACT FROM AUTHOR]

Laser surface cladding is a significant process used for improving and altering the surface properties of materials. Examples of these alterations are cladding of bulk materials with stronger and more expensive materials for enhancing the surface wear resistance, hardness, corrosion resistance, or creating magnetic property on non-magnetic material. In this paper, metal samples were laser processed by using the pre-deposited paste-powder method of laser surface cladding. Aluminium of Al6061 alloy and EN3B mild steel were chosen as the substrates, coated with the materials Inconel 718, Nitinol and 316 L stainless steel. A comparison of each of the sample's mechanical properties through specific wear rate and microhardness was conducted. It was found that all samples had improved microhardness compared to that of their substrates. Furthermore, all aluminum base samples had significantly improved wear rates by at least 72%. Microhardness increase of 3.2 and 1.5 times on the Al and steel samples cladded with Inconel and Nitinol respectively. The cross-section of all the processed samples' microstructure was examined under a scanning electron microscope. Results showed the interface of the clad layer, substrate, and a clear heat-affected zone of the mild steel samples.

Recent studies are evaluating the use of particulates fabricated from agro-based residues as reinforcement for enhancing the properties of aluminium alloys. This report focuses on the optimization approach and modeling of responses for future prediction, which are absent from the majority of studies involving particle reinforcement of an aluminum matrix. Herein, palm kernel shell ash (PKA) and rice husk ash (RHA) were incorporated with 4 wt% of WSD and used as fillers in the Aluminium-6061 matrix at variable proportions. The response surface approach was utilized in the experiment design, modeling, and outcome optimization. The independent variables are the proportions of PKA and RHA and stir casting temperature. Yield, ultimate tensile, impact strength, elastic modulus, and fracture toughness are examined as response parameters. The results demonstrated that the microstructural property played a significant role in the responses. Incorporating PKA and RHA into the Al-6061 matrix improved the response parameters. Temperatures in the range of 700 and 800 °C enhanced the property parameters, even though temperatures within 800 and 900 °C caused a decline in response. The dependence of the responses on the pattern between property variables was revealed by surface and contour plots. The development of models for predicting responses. Optimal conditions were reached at 4.03% PKA, 5.12% RHA, and 787 °C, with an error

The study investigates the mechanical, and tribological properties of Al6061-SiC-NSA hybrid composites. The characterization via FE-SEM reveals NSA particle’s crystal structure and agglomeration, with an average particle size of approximately 400 nm. The EDS analysis confirms the presence of oxides (TiO _2 , SiO _2 , Fe _2 O _3 , Al _2 O _3 ) along with calcium and potassium. The XRD spectra corroborate these findings, additionally identifying Calcite and intermetallic compounds. The Al6061–5SiC-10NSA composites has improved compressive strength of 254 MPa compared to 220 MPa for base Al6061 alloy. The tensile strength of base Al6061 (100 MPa) decreased to 70 MPa for Al6061–5SiC-20NSA composites. The tensile strength decreases with increasing NSA content. Fracture analysis indicates ductile fracture mechanisms, supported by FE-SEM images displaying honeycomb-like structures and dimples. Impact testing reveals reduced impact strength in composites compared to Al6061 (26J ^3 ), with Al6061–10SiC-5NSA exhibiting the best toughness of 22.5 J ^3 . Density decreases in composites, with density of Al6061–5SiC-20NSA composites has reduced to 2.40 g cm ^−3. The microhardness of Al6061–10SiC-5NSA has better value of 109 HV, whereas further addition of NSA has resulted in decrease in microhardness of composites. Pin-on-disc wear tests demonstrate improved wear resistance with increased NSA content, with Al6061–5SiC-20NSA outperforming other compositions. COF decreases with increased NSA content and sliding speed. FE-SEM analysis of worn surfaces reveals that the major wear mechanism is adhesive wear followed by delamination, further the oxide formation along the surface aiding wear resistance of the composites. Tafel testing indicates decreased corrosion potential with increased NSA content, with Al6061–5SiC-20NSA exhibiting improved corrosion resistance.

Al composites usage is growing and is gaining importance in aerospace, automotive and marine industries due to their excellent characteristics. Aluminum composites exhibit high resistance to wear and corrosion, possess high strength, offer durability and more such properties. In this study, Al 6061 alloy, reinforced with Al2O3 - MoS2 was produced by a stir casting technique and its microstructure and mechanical behavior were evaluated. Reinforcements were added in the range of 0 - 9 wt. %. The microstructure analysis, tensile and compressive strength of the hybrid MMCs (Metal Matrix Composites) have been analyzed and examined. From the investigational study, it was found that the reinforcing particulates are evenly dispersed in the base matrix. The porosity and density of the hybrid composites were found to be enhanced. The ultimate tensile and compressive strength of the hybrid MMCs could be improved by addition of ceramic (Al2O3) particulates compared to monolithic. Further, the strength of hybrid composites was decreased by adding of MoS2 (solid lubricant) along with hard ceramic particulates. Finally, fractured surface of the UTS test specimens were analysed using a SEM analysis

Solid-state Friction Stir Additive Manufacturing has recently gained attention as a result of its capacity to fabricate large-scale parts while preserving the mechanical properties of the feedstock material. However, the correlation between the quality of layer-by-layer bonding of the deposited metal and processing parameters has remained unknown. Neutron imaging techniques, with 90% total transmission per cm, are employed for Al6061 parts fabricated by MELD® Technology as a non-destructive evaluation approach for the first time to investigate the layer-by-layer structure of a stadium-shaped ingot in different sections. The post-processed results show the fabricated parts with an optimized set of processing parameters are void-free. However, the hydrocarbon-based feedstock lubricant segregates between the layers, which consequently may lead to non-uniform weaker mechanical properties along the build direction and stimulate crack initiation during mechanical loading. The tensile test results show 14% lower strain-to-failure values in alleged contaminated areas in transmission imaging results. Additionally, layer bonding is significantly impacted by hot-on-hot and hot-on-cold layer deposition schemes, especially for larger layer thicknesses. [ABSTRACT FROM AUTHOR]

The friction stir process (FSP) is becoming a highly utilized method to manufacture composites since it refines the microstructure and improves the physical characteristics like hardness, strength, and wear resistance of their surfaces. In this study, the hardness and wear behaviours of Al6061-based surface composites prepared by the FSP were investigated and compared for the influences of various parameters—FSP tool geometry, reinforcement composition, number of FSP passes, pin load, etc. The Taguchi design with an L27 orthogonal array was developed to analyze the influence of five input parameters on the output parameter, i.e., wear rate during wear tests. The hardness of the composite samples for different reinforcement compositions was investigated, and the results were statistically compared with the obtained wear rates. It was concluded from the results that various parameters influenced the surface wear and hardness of the composites. Tool geometries cylindrical pin and square pin had the maximum and minimum wear rates, respectively. Additionally, the optimal composition of the reinforcements copper and graphene as 1:3 possessed the maximum wear rate and minimum hardness. However, the reinforcement composition 3:3 (Cu:Gr) by weight had the minimum wear rate and maximum hardness. The higher the FSP pass numbers, the lesser the wear rate and the higher the hardness, and vice-versa. This work helps identify the influence of numerous factors on the wear and hardness aspects of surface composites prepared by the FSP. In the future, this study can be modified by combining it with thermal analysis, sensor data analysis of the composites, and optimization of the parameters for desirable microstructure and physical properties. [ABSTRACT FROM AUTHOR]

In this research an attempt is made to improve and to examine the wear behaviour of AL6061 composite with two different fillers such as graphite by adding the reinforcement particles of palm stalk ashes. AL6061 composite is developed on a metal matrix composite with the weight percentage of graphite (0.7 %) which is kept constant for all specimens and the reinforcement of palm stalk ash is varied as a percentage of weight (0.7%, 1.4%, 2.1%, 2.8% and 3.5%). Reinforced composites were preheated in the electrical furnace at 150°C for about an hour to remove the moisture. The reinforcement was added into molten aluminium into the stir casting furnace. The wear behaviour and corrosion rate of fabricated AL6061 metal composite reinforced with different dissipate materials were studied. [ABSTRACT FROM AUTHOR]

Blending or supplementing metals with cutting-edge Metal Matrix Composites (MMCs) endeavours to improve the safety, reliability weight and productivity. A hybrid MMC was produced for the chamber liner of cutting-edge diesel motors. Dry sliding wear testing equipment, employing a pin-on-disc wear tester, is used to examine the wear properties of casted hybrid metal matrix composites. The examination shows that the wear opposition of Al-6061 is expanded while adding the chicken bone ash and graphite as support content. Within the current work, effort has been made to survey the tribological properties of aluminium as-projected combination test for Al amalgam and unadulterated aluminium. The operational boundaries were a typical load and sliding velocity of the pin concerning rotating disk at temperature. The medium utilized was dry and wet greasing. The amount of mileage has been decreased altogether in aluminium alloy similar to unadulterated aluminium. Dry condition testing showed huge loads of noise and a similarly more measure of mileage for both aluminium and aluminium alloy. The coefficient of contact for aluminium alloy in wet conditions was roughly steady up to the applied load and then diminished with additional utilization of load while the coefficient of friction for unadulterated aluminium was rising persistently with the load. Evaluation of the corrosion conduct of the aluminium MMC is achieved by the usage of the salt spray method or immersion test and the results are considered. [ABSTRACT FROM AUTHOR]

Aluminum alloys specifically Al6061 have widespread applications; however, its processing is challenging via conventional means due to chip adhesion and burr formation. Moreover, it is difficult to attain dimensional accuracy of the machined profile in the said alloy especially if the size of the machined profile is in a micron which is a common requirement in case of microchannels' formation. Microchannels have wide applications in biomedical, chemical, and electronics industry. Therefore, in this study, the potential of EDM is comprehensively investigated for machining of dimensionally consistent microchannel(s) in Al6061. Single, double, and triple microchannel(s) are produced using laminated brass electrode(s) employing Taguchi (L18) design. The dimensional error was measured for each of the produced microchannel(s) using coordinate measuring machine (CMM). It has been revealed that number of channels and electrode thickness is the significant factors contributing 84.9% and 4.7%, respectively, to the depth deviation (Dd). Dd increases with increase in number of channels and electrode thickness. Electrode thickness is the most influential parameter (85.4%) affecting width deviation of microchannel(s). Width deviation experiences, a drop when a thicker electrode is engaged. The thinnest electrode (0.2 mm) has provided the highest value of arc radius which translates to flatter base of channel. [ABSTRACT FROM AUTHOR]

Age-hardenable aluminum alloys are of interest for powder bed fusion (PBF) additive manufacturing to produce lightweight, high-performance custom components. The successful processing of these alloys depends on specific alloying and print techniques to overcome defects that significantly degrade mechanical properties of PBF aluminum. The Reactive Additive Manufacturing (RAM) process modifieds alloy feedstock with reactive precursors which inoculate equiaxed microstructures during solidification, resulting in a reduction of columnar grain growth and shrinkage cracks. Additionally, surface quality is addressed by contouring, which retraces the perimeters of printed layers to produce smooth, fully fused surfaces. However, the combination of RAM and contouring methods has not been previously described in the literature, raising questions about the extent of refinement which is achieved when RAM particles are remelted by contouring laser sweeps. In this research, X-ray microcomputed tomography (XCT) was used to provide a complete characterization of RAM particles and defects in an AA6061-RAM alloy in 3D. The non-destructive XCT technique was used to quantify pore and particle distributions in the contoured alloy volumes and compared directly to hatched regions. The resulting three-dimensional analysis was correlated to traditional 2D microstructure quantification and nanoindentation experiments, providing a multimodal quantitative description of sub-micron grains, reaction products, and micromechanical properties. The study reveals that RAM particles inhibit cracking while simultaneously reducing the variance in mechanical properties between hatched and contoured regions of the build volume. • RAM particles and defects in an AA6061-RAM alloy were characterized in 3D. • Pore and particle distributions in the contoured and hatched regions were quantified. • RAM particles inhibit hot cracking while homogenizing mechanical properties in hatched and contoured regions. [ABSTRACT FROM AUTHOR]

In the present study, wear behavior of Al6061 hybrid composite having silicon carbide and red mud as the reinforcements have been studied. This hybrid composite was fabricated using the stir casting technique. Effect of variation of magnesium content, red mud content, aging time, red mud particle size, applied load, displacement and speed were studied. Scanning electron microscopy confirmed the fairly uniform distribution of the reinforcement particles and provided wear patterns of this composite. Energy dispersive spectroscopy showed different constituents present in this hybrid composite. Wear loss decreased with an increase in magnesium content and aging time while it decreased with an increase in red mud content up to 4% (wt%) and particle size up to 150 mesh (105 µm). Wear loss increased with an increase in load, sliding speed and sliding distance. Load and sliding distance have a significant effect on the wear loss. Optimum values for minimum weight loss were calculated and were confirmed by confirmation experiments. Load and sliding distance have been found to have significant effect on wear loss. So this fabricated composite can be utilized in various applications like in Marine frames, Aircraft and truck frames, Chemical equipment, aircraft landing mats etc.

The plasma electrolytic method of oxidation (PEO) is a technique that is increasingly being used in industry to produce protective coatings and other surface treatments. The emphasis is then placed on the dielectric breakdown that repeatedly occurs across the surface of the workpiece. There is significant potential for more effective process control. Key study areas include the interrelation of electrical conditions, electrolyte composition, coating microstructure, and growth rates. With specific goals in terms of coating performance and energy efficiency, an attempt is made to identify key points that are likely to simplify this. The research aims to identify the optimized range of input parameters when the oxide layer is formed using the DC supply in the silicate-based electrolyte on Al 6061 substrate. For developing an oxide layer on Al 6061, a silicate-based electrolyte containing Na2SiO3 (10g/L), KOH (2g/L), and KMnO4 3 (g/lit) is applied. At the optimal parameter of DC supply with 190 V and 1.5 A, the maximal adoption of Mn particles was observed to be 34 percent.

Al composites usage is growing and is gaining importance in aerospace, automotive and marine industries due to their excellent characteristics. Aluminum composites exhibit high resistance to wear and corrosion, possess high strength, offer durability and more such properties. In this study, Al 6061 alloy, reinforced with Al2O3 - MoS2 was produced by a stir casting technique and its microstructure and mechanical behavior were evaluated. Reinforcements were added in the range of 0 - 9 wt. %. The microstructure analysis, tensile and compressive strength of the hybrid MMCs (Metal Matrix Composites) have been analyzed and examined. From the investigational study, it was found that the reinforcing particulates are evenly dispersed in the base matrix. The porosity and density of the hybrid composites were found to be enhanced. The ultimate tensile and compressive strength of the hybrid MMCs could be improved by addition of ceramic (Al2O3) particulates compared to monolithic. Further, the strength of hybrid composites was decreased by adding of MoS2 (solid lubricant) along with hard ceramic particulates. Finally, fractured surface of the UTS test specimens were analysed using a SEM analysis. [ABSTRACT FROM AUTHOR]

Joining dissimilar materials is always a challenging and interesting topic for researchers and industries. Friction drill joining, as a solid-state process, is a novel approach to connecting similar and dissimilar materials. Dissimilar metals, especially ultra-high-strength steels and aluminum alloys, are used significantly for the mass reduction of automotive bodies, and to reduce CO2 emissions in the automotive industry. In the current work, a friction drill joining technique for joining AISI304 and Al6061 was experimentally and numerically studied. A technique for improving joint strength, load-clamping modification, and tool movement was also introduced. The required thrust force is measured, and it is proven that adding sheet layers does not significantly affect the required thrust force. To understand and identify the mechanism of the process, and its material behaviour, material stirring and formation in the joint region were analyzed. A thermo-mechanical finite element model was also developed, and the thermal stress, plastic strain, and temperature were studied. A numerical comparison between joints formed under normal and improvement conditions was conducted, and the significant effect of the improvement conditions on joint strength and formed-bush quality was found. Based on the findings, the great potential of using friction drill joining for joining dissimilar materials is confirmed. [ABSTRACT FROM AUTHOR]

Aluminum and its alloys specifically Al6061 bear numerous applications in aerospace and marine etc. where dimensional accuracy is of utmost importance which favors the use of wire electric discharge machining (WEDM). However, the achievement of a similar level of dimensional consistency in terms of corner deviation at both upper and the lower face of the workpiece is challenging. The issues of wire lag and wire vibrations are the prime stimuli for provoking the said corner errors, but their influence is notably different at both the faces of the cut specimen. Essentially similar level of corner accuracy is deemed necessary at upper and lower face of the cut specimen for its accurate functionality in its end application. This aspect has not been explicitly studied so far during WEDM of Al6061 alloy which is primarily investigated in this research. Moreover, the aspect of corner accuracy has not been discussed considering the material removal rate and surface roughness to iterate an optimal setting that yields dimensionally consistent product at optimized material removal rate and surface quality which is done herein. Seven WEDM process variables have been selected to envisage their impact on the selected responses under L27 Taguchi’s design. Experimental findings revealed that corner errors realized at top and bottom faces are markedly different. Angular error at the top face is significantly influenced by Wire tension, off-time, and flushing pressure with percentage contributions of 25.5%, 12%, and 15.6% respectively. Whereas, the angular error at bottom is mainly influenced by open voltage, on time, wire feed, and flushing pressure with percentage contribution of 28.5%, 15.3%, 13.2%, and 10.7% correspondingly. In case of surface finish and material removal rate, pulse longevity is the prime control variable with contribution of 51% and 88% respectively. Greater magnitude of wire tension is observed to cause the taperness in the wire electrode that yields higher corner error at the top face. Corner errors at both the faces i.e. top and bottom are reduced at greater value of open voltages. Scanning electron microscopy analysis depicts that the crater depth and its width, material melting, vaporization, and redeposit on the machined surface are increased by increasing spark duration and subsequently poor surface finish is achieved. An optimal parametric combination for simultaneous optimization of the conflicting responses has been proposed using weighted signal-to-noise ratio. The adequacy of the developed optimal combination has also been validated via confirmation trials.

Molecular dynamics simulations were employed to understand the diffusion bonding process during hot isostatic pressing (HIP) of Al6061/Al6061 alloy. Simulations of the HIP process reveal atomistic phenomena that are difficult or unlikely to be observed experimentally and provide useful insights into the mechanism of diffusion and bonding. The results reveal that at the start of the HIP process, a massive incursion of oxygen atoms occurs from the pre-existing γ-Al 2 O 3 to the 6061 region across the interphase interface. These oxygen atoms interact with the enriched Mg atom layer present at the existing γ-Al 2 O 3 and 6061 matrix to form a secondary complex Mg 2 Al 2 O 5 phase. Diffusion calculations also show that transport of atoms due to the applied pressure is 4–5 orders of magnitude higher than would occur in the absence of HIP conditions. The Mg 2 Al 2 O 5 phase also provides efficient pathways for the rapid transport of Mg atoms. Because of the higher diffusion coefficients observed for Mg within the phase, Mg atoms can move more swiftly compared to their diffusion within other phases such as γ-Al 2 O 3. This accelerated mobility facilitates the rapid movement of Mg atoms across the interface, leading to changes in the local composition and the potential growth of the Mg 2 Al 2 O 5 phase. [Display omitted] [ABSTRACT FROM AUTHOR]