Al-TiB2 Composites Research Articles

Effect of Hot Rolling on the Mechanical and Corrosion Properties of Altib2 Composites

Effect of Hot Rolling on the Mechanical and Corrosion Properties of Altib2 Composites

Machining Characteristics of Stir-Cast Al-TiB2 Composites in Dry Turning

Machining Characteristics of Stir-Cast Al-TiB2 Composites in Dry Turning

Microstructural, Mechanical and Wear behaviour of in-situ Al-TiB2 composites

ABSTRACT In this study, mechanical and wear properties of in-situ stir cast Al-TiB2 composites were investigated. The composites were prepared by a metal salt reaction with different (3.0, 5.0 and 7.0 wt %) TiB2 contents. The microstructure of the composites were examined through an optical and scanning electron microscopy (SEM/EDS). The microstructures clearly revealed the uniform distribution of TiB2 particles in the Al matrix. The hardness of the in-situ Al-TiB2 based composites increased by 42%, 55%, and 58% compared to the matrix with the addition of 3, 5, and 7 wt% TiB2 reinforcements, respectively. The tensile strength of the 3, 5, and 7 wt% TiB2 stir-cast composites increased by 25%, 33%, and 45%, respectively, compared to the matrix, whereas the ductility decreased by 4.9%, 24.3%, and 41.3%, respectively. A pin-on-disk tester was used to perform a dry sliding wear test at different loads and sliding speeds. In comparison to the Al matrix, the composite materials showed improved wear resistance. Furthermore, in the entire applied loads and sliding velocities, the wear rate decreased with the increase in TiB2 content. The composites displayed lower wear rates due to their high hardness and strong interfacial bonding between the in-situ reinforcement and the matrix alloy.

Characterization, nanomechanical, and wear attributes of sintered Al–TiB2 composites

Herein, Al–TiB2 composites ranging from 2 to 8 wt.% TiB2 addition developed through a Turbula mixer and fast-assisted sintering technology were investigated. The distinct phases and morphologies of the fabricated compacts were assessed via the X-ray diffractometer and scanning electron microscope. The mechanical and wear properties of the fabricated compacts were evaluated. The dispersal of TiB2 particles and the formation of an interface phase were noticed on the microstructure of the fabricated specimens. The diffractogram confirmed the presence of the TiB2 phase and Al5Ti3 phase at the plane (002), corresponding to the 2-theta value of 44.9°. The relative density of the fabricated specimens indicated an average of 99.33%, while the microhardness values were in the range of 33.1–41.3 HV1. Adding the TiB2 particle to the Al matrix raised the tensile strength value to 140 MPa on account of good dispersion of the TiB2 particle restricting the dislocation movement in the composites, further strengthening the Al–TiB2 composites at the cost of its ductility. The nanoindentation values (elastic modulus and hardness) of the fabricated Al–TiB2 composites improved compared to the fabricated Al matrix. TiB2 improved the wear properties of the fabricated Al–TiB2 composites by lowering it. Delamination, oxidation, and adhesion wear mechanisms are the noticeable wear observed from the fabricated Al–TiB2 composites. The image of the fractured Al–TiB2 composites depicts dimples and microvoids, which are the characteristics of ductile fractures.

Fabrication of Al-YOF/TiB2 composites by molten-salt-assisted stirring casting

The poor wettability between oxides and Al melt and presence of alumina film on Al melt surface seriously limits the fabrication of Al matrix composites (AMCs) reinforced by oxides via casting method. The wettability of oxides can be improved by modification with fluorine, and the oxyfluoride is more feasible to incorporate into Al melt, but the strength of the oxides may decrease after modification. Therefore, it is necessary to assess the strengthening effect of oxyfluoride by comparison with classical reinforcement. In this work, AMCs reinforced with yttrium oxyfluoride (YOF) and TiB2 were successfully fabricated by molten-salt-assisted stirring casting. YOF particles exhibit a better distribution in Al matrix than TiB2 particles, and the YOF particles show better bonding strength with Al matrix than TiB2 due to reactive wetting. Al-YOF composite shows higher hardness, tensile strength, and ductility than Al-TiB2 composite. The values of microhardness, yield strength (σ0.2) and ultimate tensile strength (σb) of Al-YOF composite are 27.2 HV, 55 MPa and 81 MPa, which are 25.9 %, 62 % and 53 % higher than that of pure Al.

Small punch testing of Al-TiB2 composites fabricated by spark plasma sintering: A computational and experimental study

The Small Punch Test (SPT) method is especially useful for quantifying the mechanical properties of metallic materials in cases where the material available for testing is limited or for in service monitoring. However, the applicability of this method to metal matrix composites has not yet been fully established. In the present study, Al-TiB2 composite billets with TiB2 particle volume fractions of 5%,10% and 15% were manufactured using Spark Plasma Sintering (SPS). Thin specimens with 0.5 mm thickness were cut from the billets, and SPT experiments were conducted until failure. Well-accepted analytical techniques were utilized to determine the Al-TiB2 composite effective yield stress for all TiB2 particle volume fractions. It was shown, that standard analytical methods for characterizing the effective yield stress were adequate only for TiB2 volume fractions of up to 5%. The experimental mechanical response up to and including failure was reproduced for all Al-TiB2 compositions by finite element analysis incorporating a continuum damage mechanics approach. The computational analysis revealed that for high TiB2 volume content, the region of the SPT loading curve which is commonly associated with specimen yielding, may represent a mixture of yielded and damaged areas. Since the damage distribution in the specimen influences the specimen flexural modulus, standard analytical relations cannot be used to determine the composite yield stress and computational methods must be used. This finding may explain the inconsistent results reported in the literature with regard to the accuracy of the SPT method in determining the effective yield stress for metal matrix composites.

Machining quality comparison of Al-TiB2 composite using conventional EDM and magnetic force-assisted powder-mixed EDM

ABSTRACT Now a day’s researchers are working hard to improve the process performance of unconventional or advanced machining processes by hybridising them with other mechanisms. In the present research, a hybrid variant of electrical discharge machining (EDM) has been proposed by developing a setup to create a rotating magnetic field near the machining zone and also by mixing a conductive powder (chromium, 325 mesh size) on a separate dielectric tank. The machining performance of indigenously developed hybrid magnetic force assisted powder mixed electric discharge machining (MFPEDM) has been compared with conventional EDM during machining of Al-TiB2 metal matrix composite. The comparison results elucidate considerable improvements in material removal rate (39.27%), surface finish (54.45%), and overcut (44.97%) by MFPEDM as compared to EDM.

Abrasive wear behavior of Al-TiB2 and Al-TiB2-nano-graphite metal matrix composites

This paper deals with abrasive wear behavior of two different composite materials namely Al-TiB2 and Al-TiB2-nano-graphite. At the time of fabrication, ultrasonic vibration is used along with mechanical stirrer to obtain uniform dispersion of micro (TiB2) and nano (graphite) reinforcement phase. Uniform dispersion is confirmed through SEM images of cast composites. Micro-hardness values are obtained for composites and base alloy. Wear tests under two-body abrasion are performed by a tribological test apparatus where composite pins are being rubbed against a disc holding different grades of SiC abrasives: 240 grit, 320 grit and 400 grit. Operating load is varied between 10N and 30N while sliding speed and duration of sliding are kept fixed. Effects of load, reinforcing phase content and abrasive grit size on abrasive wear and friction behavior have been evaluated. Al-TiB2 composites demonstrate higher wear resistance and better friction behavior in comparison with base alloy under all operating conditions. Addition of nano-graphite phase contributes in achieving better abrasive wear and friction performance of Al-TiB2 composites. With increase in grit size, wear reduces for composites and base alloy while wear increases with load. Worn surfaces of samples and emery papers are studied using SEM micrographs and EDX maps. Wear debris at different operating conditions are studied also using SEM and EDX. Operative wear mechanisms are identified from the experimental results.

Mechanical Properties of Titanium Diboride Particles Reinforced Aluminum Alloy Matrix Composites: A Comprehensive Review

Aluminum alloys with silicon, magnesium, and copper were extensively used alloying elements in various applications because of their excellent properties. In recent decades, aluminum matrix composites (AMCs) are an advanced engineering material widely utilized in diverse engineering applications, including aircraft, automobile, marine, and shipbuilding, owing to their low density, lightweight, good stiffness, superior strength, and good tribological properties. Aluminum is abundant and its use is as vast as the ocean. It is also the most used matrix material in the composite arena. Therefore, incorporating a ceramic particle into a relatively soft aluminum matrix improves hardness, strength, stiffness, creep, fatigue, and wear properties instead of the conventional materials. This article is an assay to review and spotlight some recent works on the mechanical behaviors of aluminum‐based titanium diboride reinforced metal matrix composite. This review article concentrates on the mechanical properties and the fabrication processes of Al‐TiB2 composites to provide a valuable reference to nurture future research precisely.

Multicriteria Selection of Friction Stir Welded Al-Tib2 Metal Matrix Composites using WASPAS to Improve Composite Development and Design

The unique area of friction stir welding that involves Al-TiB2 composite development stirs controversy and fails to offer a clear understanding of how to choose the best composite among alternatives without subjectivity. At present, the experienced fabricator uses intuition in judgement, leading to wrong or inconsistent decisions. In this paper, the WASPAS multicriteria model is deployed to choose the best Al-TiB2 composite among options using tensile strength, ductility and microhardness as attributes. The procedure generally entails normalization, preference score and ranking determination and literature data was used. The emerging conclusion from this study is that irrespective of the weight determination method and the multicriteria model adopted to evaluate the alternative fabricated Al-TiB2 composites, the Al-10%TiB2 and Al6065 based alloy always reveal as the best and worst composites, respectively, even under varied normalisation methods. The research confirmed that multicriteria analysis is a potential objective method to choose among fabricated alternatives. The work showed that there is scope to evade the consequences of subjectivity in composite decision making by attaching adequate weights to the deciding factors thereby avoiding misguidance and incorrect decision making. Furthermore, multicriteria models offer novel approaches to understand the relative preference of fabricating composites to one another in the metal matrix composite development area.

Comparative Evaluation of Ex Situ and In Situ Method of Fabricating Aluminum/TiB2 Composites

In the present work, Al–TiB2 composites were casted using in situ and ex situ method of fabrication. The effect of processing temperature on the formation of titanium diboride particles was studied, and comparative evaluation of in situ and ex situ method was carried out. Characterization of composites was carried out to study the effect of various process parameters on the mechanical properties. The microstructure of in situ composites shows a homogeneous distribution of titanium diboride particles without agglomeration as compared to ex situ composites. SEM micrographs of in situ composites show distinct and reaction-free boundaries between reinforcement and matrix material as compared to the ex situ composites. In addition, average UTS of in situ AlSi5Cu3/3%TiB2 composite and ex situ AlSi5Cu3/3%TiB2 composite increased by 80.13% and 39.72% as compared to pure AlSi5Cu3, respectively. The average hardness of in situ AlSi5Cu3/3%TiB2 composite and ex situ AlSi5Cu3/3%TiB2 composite casted in metal mold increased by 45% and 31.66%, respectively, as compared to pure AlSi5Cu3.

Spark Plasma Sintering and Characterization of Al-TiB2 Composites

In this study, Al-TiB2 compacts fabricated by spark plasma sintering methods at different temperatures were characterized for densification, microstructural development, and mechanical properties. Sintering parameters used were temperatures of 500 °C and 550 °C under the pressure of 30 MPa. A very dense microstructure with uniform phase distribution and porosity was produced in the sample sintered at 550 °C with 2.5 wt% TiB2. The same sample exhibited excellent hardness value, and a high-tensile strength attributed to full metallurgical bonding, presence of sub-micron sized grains, and their uniform distribution. These results show that the TiB2 addition enhanced the composite’s hardness, sintered density, and tensile strength. In all the sintered samples, the fractographs revealed a mixed-mode fracture (ductile and brittle).

Cold Forming of Al-TiB2 Composites Fabricated by SPS: A Computational Experimental Study.

The mechanical response and failure of Al-TiB2 composites fabricated by Spark Plasma Sintering (SPS) were investigated. The effective flow stress at room temperature for different TiB2 particle volume fractions between 0% and 15% was determined using compression experiments on cylindrical specimens in conjunction with an iterative computational methodology. A different set of experiments on tapered specimens was used to validate the effective flow curves by comparing experimental force–displacement curves and deformation patterns to the ones obtained from the computations. Using a continuum damage mechanics approach, the experiments were also used to construct effective failure curves for each material composition. It was demonstrated that the fracture modes observed in the different experiments could be reproduced in the computations. The results show that increasing the TiB2 particle volume fraction to 10% results in an increase in material effective yield stress and a decrease in hardening. For a particle volume fraction of 15%, the effective yield stress decreases with no significant influence on the hardening slope. The ductility (workability) of the composite decreases with increasing particle volume fraction.

Planetary Milling and Self-Propagating High-Temperature Synthesis of Al-TiB2 Composites.

The paper explores the influence of planetary milling on the temperature and velocity of Al-Ti-B powder mixture combustion and also on the structure and phase composition of the reaction products. It is found that the time increase of planetary milling modifies the structure of the powder particles, improves the density of compacted specimens, and increases the temperature and velocity of their combustion. These time dependences are extreme, with maximum values during 180 s planetary milling. Experiments show that the reaction products consist of an aluminum matrix with uniformly distributed particles of titanium diboride of not over 1 µm in size. The average particle size changes with the increase in the time of the planetary milling of the initial powder mixture.

Analysis of Triangular WEDM Cut Corner Inaccuracy of Aluminium Composite Mold Material

Aluminium Composite mold has been used exclusively in industries such as Aerospace, Automobile, Medical Equipment, Transportation, and Marine. They are preferred due to efficient heat transfer and strength. These molds are used to produce seat foams, urethane panels, silicone patterns, MRI instrument covers. Leakage in any of the products due to machining inaccuracy in corners will lead to serious problems. Therefore, the corner inaccuracy has been investigated. Composite mold material is made of Al-TiB2. Wire EDM can be used for machining Al-TiB2 composite efficiently and the optimization of the parameters in WEDM such as MRR, surface roughness, and corner inaccuracy. Triangular profile of 60° angle with sides 30 mm was cut from the composites. Composites machining done with wire electric discharge technique by varying control factors wire tension, spark voltage, pulse on duration, and pulse off duration. Machining experimentation was done using a brass tool electrode wire and size of 0.25 mm in diameter. The surface roughness (Ra) of the cut was evaluated through a surf-tester with a sampling length of 0.8 mm. To examine a corner inaccuracy of the machined surface, OM pictures were taken on the machined surface of Al-TiB2 composites. Calculation of inaccuracy in the corner was done using ImageJ software. The corner inaccuracy can be estimated by subtracting a machined area from actual area. By calculating the inaccuracies of machined composites, it was found that the minimum deviation in corner area was observed in the machining conditions of maximum wire tension (WT) and maximum Pulse on time (Ton). Wire Tension provided less deflection during the machining. The less deflection in wire provided stable sparks and constant inter-electrode gap providing the least corner inaccuracy during machining. In order to increase corner accuracy, the wire tension can be increased to a certain limit and above that which the wire tends to break due to the presence of non-conductive ceramic particles in the aluminium matrix.

Design of Experiments Analysis of Abrasive Wear Behavior of Stir Cast Al-TiB2 Composites

Abstract Present study deals with the abrasive wear behavior of Al-TiB2 metal matrix composites. Composites have been fabricated through stir-casting method containing three different weight percentages of reinforcement. Abrasive wear tests have been performed in pin-on disk tribometer carrying bonded abrasive silicon carbide papers of three different grades. Wear values are obtained in terms of weight loss after completion of the each test. Wear results are obtained according to the design of experiments based on Taguchi L27 orthogonal array. Weight percentage (wt %) of TiB2, load and grade of the abrasive papers have been chosen as design parameters. For each parameter, three different levels are used. Taguchi method is applied on the wear results to find out the optimal combination of parameters. Analysis of variance is performed to get the idea about contribution of each parameter and their interactions. Abrasive wear mostly depends on the abrasive particle size. With increase in the particle size, wear increases. As per ANOVA table, abrasive particle size holds 74.41% contribution in influencing wear behavior.

Design of experiments analysis of abrasive friction behavior of Al-TiB2 composites

Abstract Present study deals with the abrasive friction behavior of Al-TiB 2 metal matrix composites. Composites have been fabricated through stir-casting method containing three different weight percentages of reinforcement. Abrasive tests have been performed in pin-on disk tribo-meter carrying bonded abrasive silicon carbide papers of three different grades. Friction values are obtained directly from the setup after completion of the each test. Coefficient of friction values are calculated according to the design of experiments based on Taguchi L27 orthogonal array. Weight percentage (wt%) of TiB 2 , load and grade of the abrasive papers have been chosen as design parameters. For each parameter, three different levels are used. Taguchi method is applied on the coefficient of friction values to find out the optimal combination of parameters. Analysis of variance is performed to get the idea about contribution of each parameter and their interactions. Friction during abrasion mostly depends on the abrasive particle size. With increase in the particle size, friction increases. As per ANOVA table, abrasive particle size holds 97.3% contribution in influencing friction under abrasion.

HIGH TEMPERATURE TRIBOLOGICAL BEHAVIOR OF STIR-CAST Al–TiB2 METAL MATRIX COMPOSITES

This study considers high temperature tribological behavior of Al-TiB2 aluminum matrix composites (AMCs) fabricated through stir cast method. Effect of operating temperature on wear and friction behavior is studied for four different weight percentages of reinforcements using a high-temperature tribo-tester over a temperature range of 50[Formula: see text]C–250[Formula: see text]C under normal load in the range of 25–75[Formula: see text]N. Surface morphology and wear debris are studied through scanning electron microscopy (SEM) images. Energy dispersive X-ray (EDAX) and X-ray diffraction (XRD) studies are performed to observe the wear mechanism at high temperature. Increase in the amount of reinforcement improves wear resistance of composites at all temperatures. Friction and rate of wear are found to increase with operating temperature. Formation of oxide layers and softening of the surface are found to play crucial role in controlling the tribological behavior of stir cast Al–TiB2 composites at high operating temperatures.

Effect of cryomilling on matrix/reinforcement interfaces and properties of Al-TiB2 composites

The present study reports the effects of cryomilling on the microstructural and mechanical properties of pressurelessly sintered Al-xTiB2 (x = 5, 10, or 15 wt%) composites. Composite powders milled under cryogenic conditions in the presence of liquid nitrogen were compacted in a hydraulic press, and the compacts were pressurelessly sintered at 650 °C for 5 h under Ar/H2 gas. The effects of cryomilling time (10 or 20 min) and TiB2 content (5, 10, or 15 wt%) on the microstructures, densities, and mechanical properties (wear characteristics, hardness, elastic modulus, indentation response) of the sintered products were investigated. Because the milling process was under cryogenic conditions, the formation of intermetallic phases between the matrix and reinforcement particles, such as Al3Ti, was not observed at the interfaces of the sintered Al-TiB2 composites, even when 15 wt% TiB2 was used. Cryomilling for 10 min followed by pressureless sintering of Al matrix composites reinforced with 5–15 wt% TiB2 particles resulted in bulk samples with relative densities of 97.38–98.43%, hardness values of 0.75–1.35 GPa, wear volume losses of 0.276–1.265 mm3, and elastic moduli of 283–433.7 GPa.

Design of Experiments Analysis of Wear Behavior of Stir Cast Al-TiB2 Composite in Lubricated Condition

The present study considers the wear behavior under lubricated condition of aluminum matrix composites reinforced with TiB2 micro particles. Different weight percentages of micro-TiB2 powders with average sizes of 5-40 micron are incorporated into molten LM4 aluminum matrix by stir casting method. Wear in terms of depth of Al-TiB2 composites is evaluated in a block-on-roller type Multi-tribo tester at room temperature in presence SAE20W40 petroleum based lubricant. Taguchi L27 orthogonal array is used as design of experiment. Taguchi method is implemented to find out the optimal combination of parameters. Analysis of variance (ANOVA) is used to find out the percentage of contribution of each parameter on wear depth in lubricated condition. Presence of lubricant shows the negation of effect of weight percentage of particulate in the interacting surface region. Load is the most influential factor as it determines the film thickness of the lubricant in a very definite way.