TiB2 Reinforcement Research Articles

Synthesis and characterization of AA7075/TiB2 aluminum matrix composite formed through stir casting method

In the present investigation AA7075 alloy reinforced with varying the weight % (wt.%) (6%, 9% and 12%) of Titanium diboride (TiB2) were prepared AA7075/TiB2 AMCs by stir casting method using in situ reaction of K2TiF6 and KBF4 salts. For phase analysis of composite material, X-ray diffraction analysis was performed to determine the presence of TiB2 reinforcement in the composite without presence of other inter metallic compounds. From microstructural analysis it was observed that the reinforcement particles were almost uniformly distributed in the aluminum matrix and the grain size decrease with increase in wt.% of the reinforcement. Ultimate tensile strength (UTS) and hardness of AA7075/TiB2 AMCs increase with increase in wt.% of TiB2 reinforcement. Fractography analysis reveals that the tensile specimens were fail in ductile mode of fracture.

Investigation on mechanical and tribological behaviour of titanium diboride reinforced martensitic stainless steel

The role of metal matrix composites (MMCs) has gained huge momentum in various researches as well as in industrial applications due to their high stiffness and higher strength to weight ratio. It helps in achieving enormous weight reduction without compromising the strength of the material. In this study, a novel attempt was made to fabricate MMCs with martensitic stainless steel as matrix and titanium diboride (TiB2) as reinforcement. The AISI 420 matrix with different weight percentages (1%, 2%, and 4%) of TiB2 reinforcement was fabricated by vacuum induction melting technique (VIM). The aim of this study was to analyze the influence of TiB2 particle addition on the mechanical and tribological properties of AISI 420 composites. X-ray diffraction studies revealed the presence of TiB2 phase in the composite along with peak shifting and broadening of the steel matrix due to induced strain. Optical microscopy showed the distribution of TiB2 particles in the matrix along with a significant amount of grain refinement of the composite due to the addition of TiB2. Microhardness results showed that the presence of TiB2 improved the hardness with AISI 420/4%TiB2 composite possessing the maximum hardness. Tensile test results indicated a significant improvement in the ultimate tensile and yield strength of the composite with the addition of TiB2. The wear tests were carried out on a pin on disc tribometer for various loads at a different sliding distance for steady sliding velocity. The dispersion of TiB2 particle helped in achieving better wear resistance of the composites. Wear surface morphology was carried out to explore the wear mechanisms. Among the various wear mechanisms, abrasion and oxidation phenomena dominated in the composites. Taguchi optimization technique predicted that wt% of TiB2 and applied load as influencing factors on the wear rate of the material.

Studies on in-situ TiB2 reinforced Al-Si alloys synthesized by stir casting method

Materials with unusual and challenging combinations of properties like low density, good strength, high stiffness along with abrasion, impact and corrosion resistance, which cannot be experienced by the conventional materials are required in many of our modern technologies needed for aerospace, underwater and transportation applications. Al-Si Alloy has been proved to be an excellent material to substitute conventional engineering materials by virtue of its good castability, corrosion resistance and specific strength. Nevertheless, in-situ TiB2 reinforcement adds to its wear properties because of its outstanding hardness and clean interface during formation. In the present study, an effort has been made to synthesize Al-Si alloys reinforced with TiB2 particles through salt metal reaction and to highlight the performance of these composites with respect to variation in silicon content accompanied by TiB2particles synthesised by stir casting method. A pin-on-disc wear testing machine has been used to investigate the dry sliding wear behaviour of these composites with varying load (10, 20, 30) N and varying speed (300, 400, 500) rpm. Microstructural characterization by Scanning Electron Microscope and optical microscope clearly explained the enhanced wear properties of the composites attributed to the variation of Si content and presence of TiB2 which alters the morphology and distribution of various phases.

Effect of pouring temperature on cast Al/SiCp and Al/TiB2 metal matrix composites

AbstractThe effect of pouring temperatures of an ex situ (Al/SiCp) and in situ (Al/TiB2) metal matrix composites (MMCs) synthesized using stir casting method were studied. The Al/SiCp composite were fabricated by mixing of 6wt.% of SiCp into cast A356 aluminium alloy melt and poured at diverse pouring temperatures (730∘C, 750∘C and 770∘C). The Al/TiB2 MMCs were obtained by melting A356 aluminium alloy and mixing of KBF4 and K2TiF6 precursor salts whose stoichiometric ratio composition corresponds to 6wt.% of TiB2 reinforcement and other parameters were constant (stirring speed 300 RPM and holding time 30 minutes). The composite melt was poured into the permanent mould with varied pouring temperatures (800∘C, 820∘C and 840∘C). Coarser and homogenous SiC particles were presented in the Al/SiCp MMCs, whereas, finer and uniformly distributed TiB2 particles were appeared at the MMCs of Al/TiB2. The mechanical properties viz. tensile strength, fracture toughness and hardness of Al/SiCp and Al/TiB2 MMCs were experimentally determined as per the ASTM standards and compared. Higher tensile and fracture strength were occurred at the MMCs of Al/TiB2 as compared to Al/SiCp MMCs and base alloy of aluminium as well. Maximum hardness was attained at the pouring temperatures of 820∘C and 750∘C in the MMCs of Al/ TiB2 and Al/SiCp, respectively.

Effect of in-situ sub-micron sized TiB2 reinforcement on microstructure and mechanical properties in ZE41 magnesium matrix composites

ZE41 Mg–TiB2 metal matrix composites with improved mechanical properties were synthesized via a novel processing route. In this process, the Ti–B system was developed without addition of third intermediate metallic Al powder, thereby preventing formation of any undesirable hazardous by-products from salt system (Al–K2TiF6–KBF4) and brittle TiAl3 intermetallic phase from master alloy (Al–Ti–B). Sub-micron sized TiB2 particles (5, 10 and 15 wt%) were reinforced in the ZE41-Mg alloy and the influence of TiB2 particles and its weight fraction on mechanical properties of composite materials were studied in details with an emphasis on microstructural characterization. The microstructural characterization shows reasonable uniform distribution of TiB2 particles in lower weight fraction of reinforcement and strong interfacial bonding with the matrix. A significant enhancement of the strength as well as grain refinement of composite were observed with increased TiB2 particles. The effect of TiB2 particle content on Young's modulus and yield strength was correlated via theoretical/mathematical modeling and experimental investigations. The strengthening mechanisms for strength enhancement of composites were established.

A study on microstructural effect and mechanical behaviour of Al6061–5%SiC–TiB2 particulates reinforced hybrid metal matrix composites

In this present work, an attempt is made to prepare Al6061–5%SiC–TiB2 hybrid composites using stir casting process by considering optimal process parameters such as stirring temperature, stirring speed, stirring time, preheating temperature, grain size and wt% of particulate reinforcement and examine their metallurgical effect and mechanical behaviour. The metal composite samples were prepared using stir casting process in which the amount of reinforcement of 5%SiC is kept constant, and second reinforcement of TiB2 is varied by its weight fraction of 2, 4, 6, 8 and 10%. The prepared dual particulates reinforced hybrid composites are characterised, and their microstructural, mechanical properties and fractograpy were evaluated as per the standards. Strong interfacial bonding between matrix and reinforcements which are the significance of improved wettability is due to Potassium Hexafluorotitanate salt addition, and preheating of particles of SiC at 800℃ and TiB2 at 250℃ is made before adding into the melt. The results revealed that the increase in addition of TiB2 increases the tensile strength, flexural strength, impact strength and hardness by decreasing their weight density, and also the influence of SiC increases the hardness of the material of newly developed composite. Also, fracture morphology of tensile failure has been studied to examine micro-mechanisms of failure, and the mode of failure of the composites was found to be ductile.

Microstructure and mechanical properties of AA 2219-TiB2 composites by squeeze casting technique

The AA2219 alloy has been investigated by using squeeze casting process and the reinforcement of TiB2 is added to improve mechanical property and grain morphology to match the requirement of aerospace and automotive industries. The AA2219 alloy and composites sample were prepared by squeeze casting process and process parameter were kept at 350 MPa squeeze pressure load, die and melt temperature as 200°C and 650°C respectively with the standard dwell time 60 s. The weight percentage (x = 0,2.5,5 and 7.5) reinforcement of TiB2 added with AA2219 alloy. The morphology and phase of prepared samples are evaluated by using light microscopy, X-ray diffraction, scanning electron microscopic and energy dispersive technique. The reinforcement of TiB2 resulted in grain refinement of alloy attaining equiaxial and homogeneous grain structure. Mechanical properties such as micro hardness and tensile strength have been enhanced by 22% and 89% respectively. Wear analysis performed on the composite with help of pin on disk setup and wear characteristic show excellent wear resistance.

Microstructure development, tribological property and underlying mechanism of laser additive manufactured submicro-TiB2 reinforced Al-based composites

Al-based composites reinforced with submicro-TiB2 particles were manufactured by selective laser melting (SLM) of powder mixture under different laser powers. The microstructure evolution and tribological property of SLM-processed AlSi10Mg/TiB2 composites were investigated. Al-based composites with high manufacturing quality and uniform dispersion of TiB2 particles throughout the matrix were obtained. The EBSD results showed that incorporation of TiB2 reinforcements imposed no appreciable influence on the crystallographic orientation and average grain size, while the grain size distribution was distinctly narrowed as a result of limitation on grain growth by addition of ceramic particles. The SLM-processed composites exhibited a continuous tendency of increasing microhardness and decreasing coefficient of friction (COF) along with wear rate with a laser power increasing from 350 to 450 W. The composites showed high microhardness of 126 HV0.2, exceeding those of the Al–Si alloys and composites processing by conventional techniques. A low COF of 0.65 and wear rate of 5.2 × 10−4 mm3N−1m−1 were obtained for bulk-form composites at 450 W due to the combined effects of high manufacturing quality, microstructure homogeneity, and sound interfacial bonding.

Understanding Friction and Wear Behavior at the Nanoscale of Aluminum Matrix Composites Produced by Laser Powder Bed Fusion

Laser powder bed fusion (LPBF) is an additive manufacturing (AM) technique for the fabrication of components with a complex design, and it is particularly appropriate for structural applications in automotive and air‐space industries. Aluminum matrix composites (AMCs) are promising materials for these uses because they are ductile, light weight, and have an excellent strength‐to‐weight ratio. Herein, a study on microstructure, hardness, and the nanoscale tribological properties of the AlSi10Mg alloy with and without ceramic particles is presented. AMCs are realized with different compositions: 10 wt% of microsize TiB2, 1 wt% of nanosize TiB2, 0.5 wt% of nanosize SiO2, and 0.5 wt% of nanosize MgAl2O4. It is found that the nanocomposites show a lower coefficient of friction (COF), whereas in the case of microsize TiB2 reinforcement, the COF is higher than with either nanosize reinforcements or AlSi10Mg alloy without reinforcement. Results indicate that the interfacial bond between the matrix and the particles of the ceramic reinforcement has a crucial role in wear processes.

Elucidating the Effect of TiB2 Volume Percentage on the Mechanical Properties and Corrosion Behavior of Al5083-TiB2 Composites

Al5083-TiB2 in situ composites with 1, 3, and 5 volume percentages of TiB2 were fabricated. The effect of different volume percentages of TiB2 reinforcement particles on the mechanical properties and corrosion resistance of these composites was investigated. The hot extrusion process resulted in fragmentation and more homogeneous distribution of TiB2 particles throughout the Al5083 matrix. Also, the grain size reduced as the amount of TiB2 reinforcement particles increased which caused the improvement of both the strength and ductility of the material. It was shown that the hardness, the ultimate tensile strength (UTS), and the yield strength (YS) of both the as-cast and extruded materials increased with increasing TiB2 content. Also, TiB2 addition combined with the extrusion process improved both UTS and elongation (El.%) of the extruded structures which can be attributed to the presence of TiB2 particles and obtained microstructural refinement by hot extrusion process. However, the extruded Al5083-5 vol.% TiB2 composite showed lower ductility in comparison with the extruded Al5083-1 vol.% TiB2 and Al5083-3 vol.% TiB2 composites. Moreover, it could be concluded that the corrosion resistance and also the pitting corrosion behavior of the Al5083 alloy do not significantly change in the presence of TiB2 reinforcement particles.

Microstructures and mechanical properties of squeeze cast in-situ TiB2/2024Al composite fabricated by applying ultrasonic vibration during solidification

The ultrasonic vibration is widely applied to break the agglomeration of tiny TiB2 reinforcements in molten TiB2/2024Al composite. To date, plenty of researches have focused on the effects of ultrasonic vibration in melt preparation, but few works has been done on introducing the ultrasonic vibration into the solidification process. In the present work, ultrasonic vibration was applied during squeeze casting of solidifying melt to fabricate in situ TiB2/2024Al composites. The effect of ultrasonic vibration and specific pressure (pressure on per unit area) on solidification behavior of α-Al matrix, matrix-reinforcements interface behavior and distribution of reinforcements were also discussed. The results suggested that although the mechanical strength changed little, the elongation to fracture was promoted evidently as the ultrasonic amplitude increasing (ultrasonic gravity casting). When the amplitude was 70 μm, the elongation to fracture, Vickers hardness, yield strength and tensile strength of composites were 15.9%, 85 HV, 119.5 MPa and 288 MPa (increased by 20.4%, 9.2%, 4.8% and 3.3% compared to gravity casting), respectively. As for the ultrasonic assisted squeeze casting, the average grain size was firstly refined from 58 μm to 43 μm when the specific pressure was promoted from 0 to 50 MPa (the ultrasonic amplitude was 40 μm). However, the microstructures were coarsened and the mechanical properties were deteriorated as further increasing the specific pressure. When the specific pressure was 50 MPa, the elongation to fracture, yield strength, and tensile strength were 15.8%, 116 MPa, and 288 MPa (increased by 19.7%, 1.7% and 3.2% compared to gravity casting), respectively.

Microstructure characterization and evaluation of mechanical properties of stir rheocast AA2024/TiB2 composite

In this research, microstructure and mechanical properties of stir rheocast AA2024/TiB2 metal matrix composite have been investigated. The working temperature was 640℃, which was the selected semisolid temperature that corresponds to 40% of the solid fraction. Two weight percentage, 4 wt%, and 6 wt% of the TiB2 reinforcements were added to the matrix. The field emission scanning electron microscope micrographs of the developed composites showed a uniform distribution of the particles in the case of the 2 wt% and 4 wt% of the reinforcements. However, the particles agglomerated as the weight percentages of the reinforcement increases to 6%. The optical microscope of the liquid cast sample showed the dendritic structure, whereas the rheocast samples showed a globular structure. The X-ray diffraction analysis confirmed the distribution of the reinforcements in the matrix and the formation of some intermetallic compounds. Mechanical properties significantly improved by the addition of the reinforcements in the matrix. An increase in tensile strength of 13.3%, 40%, 28%, and 5% was achieved for the unreinforced rheocast sample, 2 wt%, 4 wt%, and 6 wt% reinforced rheocast samples respectively, compared to the liquid cast sample. An increase in 20% of hardness was attained for the composite with 2 wt% TiB2 compared to the liquid cast sample. According to the fractography analysis, small dimples were observed on the fractured surface of the unreinforced rheocast sample, whereas small and large voids were dominant on the fractured surface of the 2 wt% composite, which shows the ductile fracture mode.

Experimental Parametric Investigation of Electrochemical Drilling of AA6061-TiB2 In Situ Composites

The composite material manufacturing via in situ route is a popular method for developing the greater mechanical properties by reinforcing smaller volume of the ceramic phases. Electrochemical machining is widely employed for drilling smaller hole, machining the micro-slots and intricate shape on any material without considering its hardness. The present paper describes the electrochemical drilling of the composites reinforced with TiB2 ceramics under various reinforcement and volume contents of TiB2. Analysis of the experimental results indicates that the electrical parameters and electrolyte concentration offer significant effect on rate of material removal, delamination and radial overcut of drilled hole. The composite has minimum rate of material removal and maximum delamination and radial overcut than unreinforced alloy under ideal machining condition. Further, the effect of electrical parameters, electrolyte concentration and volume content of TiB2 on hole qualities are investigated via scanning electron microscopy and reported.

Nanoindentation Characterization on Microhardness of Micron-Level TiC and TiB Reinforcements in in-situ Synthesized (TiC+TiB)/Ti-6Al-4V Composite

The microhardness of micro-level TiC and TiB reinforcements in in-situ synthesized (TiC+TiB)/Ti-6Al-4V composite were investigated independently by spherical nanoindentation. The morphology of indentation on the matrix, reinforcements and the reinforcement / matrix interfaces were characterized by scanning electron microscope (SEM). The influence of cracks on the load-displacement curves and microhardness were analysed and discussed. The microhardness of TiC and TiB were calculated from the load-displacement curves on reinforcements without cracks. The average microhardness of TiC and TiB in this composite were 24.1 and 19.6 GPa, respectively, which agreed with the values in other composites and coatings. These results verified that the nanoindentation method was a very useful method to characterize the microhardness of micron-level reinforcements in discontinuous metal matrix composite.

Mechanical Behavior of Titanium-Based Layered Structures Fabricated Using Blended Elemental Powder Metallurgy

Mechanical behavior of bilayered structures composed of the layer of Ti-6Al-4 V (wt.%) (Ti-64) alloy and metal matrix composite (MMC) on the base of this alloy reinforced with 5 and 10% (vol.) of either TiB or TiC particles has been studied. Structures were fabricated using blended elemental powder metallurgy and studied by tensile and three-point flexural tests. Mechanical tests were performed on uniform single-layer samples of the alloy as well as individual MMCs. In addition, bilayered structures were also tested in three-point flexural experiment. Posttest fractographic inspections were made using the SEM. The deformation energy was measured based on engineering stress–strain curves obtained on tensile test. The results were compared with the data previously reported on Ti-64 alloy fabricated using cast and wrought technique. The presence of TiB and TiC reinforcement particles in the alloy causes substantial drop in strength and ductility of MMCs as compared to uniform sintered Ti-64 alloy, since those particles provide additional sites for the cracks and pores nucleation and promote the embrittlement of material. However, when MMC layers are used in bilayered structures with Ti-64 alloy layers, the three-point flexural test demonstrates significant increase in flexure stress compared to uniform Ti-64 alloy and uniform structures of MMCs. The suitability of studied structures for antiballistic impact application is discussed.

Co-reinforcing of mullite-TiN-CNT composites with ZrB2 and TiB2 compounds

In this study, the microstructural and mechanical properties of three different mullite matrix composites were investigated. Accordingly, Mullite-TiN-CNT, Mullite-TiN-TiB2-CNT and Mullite-TiN-TiB2-ZrB2-CNT composites with 10 wt % of each TiN, TiB2 and ZrB2 reinforcement particles as well as 1 wt % CNT were prepared by the spark plasma sintering (SPS) technique. The sintering processes were conducted at 1350 °C for 5 min with a mean heating rate of 60 °C/min. The relative densities of the composites achieved were higher than 97% of theoretical density. The results of mechanical properties of the fabricated composites showed that Mul-TiN-TiB2-ZrB2-CNT composites obtained the highest hardness and fracture toughness values. XRD results confirmed the presence of mullite, TiN, TiB2 and ZrB2 phases without any additional reactions between reinforcement and matrix phases. Microstructural studies demonstrated the uniform distribution of reinforcing phases in the matrix for all composites. The fracture surface micrographs revealed the dominating transgranular fracture mode indicated the strong adhesion of the reinforcing particles to the matrix. Pulling out of CNTs was also observed in the fracture surface of composites, which plays a vital role in the fracture energy absorption and joining of interfaces.

Effect of varying TiB2 reinforcement and its ageing behaviour on tensile and hardness properties of in-situ Al-4.5%Cu-xTiB2 composite

The objective of this study is to understand the suitability of mixed salt route using stir casting technique to fabricate in-situ Al-4.5%Cu-xTiB2 (x = 3, 6, 9 and 12 wt %) composites. The mechanism behind titanium/boron-based phase evolution in Al-Cu alloy has been enlightened first time, particularly its strong influence over mechanical behaviour was examined. The in-situ TiB2 reinforcement particles were prepared by the exothermic reaction of K2TiF6 and KBF4 salts in melted aluminium copper alloy which improves the hardness, yield, and tensile strengths to the extent of ∼89 VHN, ∼236 MPa and ∼295 MPa, respectively. Preliminary microstructural evolution was analysed and discussed through optical microstructures and proposed mechanism. The composites were characterized carefully with the help of field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) to know the morphological details and TiB2 distribution in the aluminium matrix composite (AMC) microstructure. In support with electron microscopic observations, the X-ray diffraction (XRD) and Electron Probe Microscopic Analysis (EPMA) were also performed. To further enhance the mechanical properties, T6 heat treatment (HT) was done. During the HT process, the composites were solutionized at 540 °C for two hours followed by water quenching. After that, artificial ageing was carried out at 170 °C with varying durations of 5, 10, 15, 20, and 25 h and post-ageing effect on the mechanical properties were recorded. Composites were thermally characterized through differential scanning calorimetry (DSC) to learn the precipitation kinetics and compared with alloy chosen.

Development and Characterization of In Situ AlSi5Cu3/TiB2 Composites

The present investigation focuses on improvement in mechanical properties of AlSi5Cu3 aluminum alloy by in situ synthesis of TiB2 reinforcement particles. Stochiometrically calculated amount of potassium tetrafluoro borate and potassium hexafluoro titanate were used for the development of 3 and 6 wt% particles of TiB2 in the liquid metal. The melt having TiB2 particles was allowed to solidify naturally in the sand mold. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the formation of hexagonal TiB2 particles within the matrix. Microstructural studies concluded the formation of micron size TiB2 particles and reduction in grain size. Ultimate tensile strength increased from 21 to 64% and hardness increased from 30 to 50% compared to AlSi5Cu3 alloy due to the formation of 3% and 6% TiB2 particles, respectively.

Development of wear maps of in-situ TiC+TiB2 reinforced AZ91 Mg matrix composite with varying microstructural conditions

Abstract In the present work, dry sliding wear behavior of AZ91 Magnesium alloy with different microstructural conditions are investigated under a set of processing parameters. The investigations are carried out on four material conditions: (i) AZ91 Magnesium alloy, (ii) AZ91 alloy with precipitate, (iii) AZ91 alloy with in-situ TiC + TiB2 reinforcement and (iv) AZ91 alloy with both precipitate and in-situ reinforcement. The effect of microstructural modification on different wear mechanisms namely: abrasive, oxidation, delamination and melt wear is established. The processing windows for all the four types of wear mechanism are established and the wear mechanism maps are also constructed by correlating the microstructures of worn surfaces and test parameters. The inherent mechanisms of all the four types of wear behavior are established for all the material conditions.

Investigation of erosion-corrosion of aluminium alloy composites: Influence of slurry composition and speed in a different mediums

In the present study, an effort has been taken to fabricate and compare the erosion-corrosion of aluminium alloy (ADC12) based composite as ADC12-7%SiC and ADC12-7%TiB2 in Basic, Acidic, Seawater and Aqueous atmosphere. TiB2 reinforced composite revealed better hardness when compared to that of SiC composite. Erosion-corrosion of aluminium alloy composites were performed at different erodent concentrations (40, 60, 80 wt%) and a speed of 1000, 1500 revolution per minute. It is marked by the study that composites show ameliorate wear resistance than alloy at all speeds and all concentrations except in Basic medium. Microstructural analysis elicited Al-Si interfaces to be a preferential site for corrosion attack. Addition of reinforcement reduces the metallic area for erodent attack; hence composites show less material loss than the alloy. Among composites, TiB2 reinforcement composite show ameliorates wear resistance irrespective of speed, slurry concentration, and slurry medium. However, regardless of the material, the material loss at 1000 rpm is more than 1500 rpm in Basic media. Based on the analysis, Material removal has the following order in different mediums as; Basic > Acidic > Marine > Water.