Distribution Of TiB Research Articles

Analyzing the synergistic effects of hard ceramic TiB2 and rare earth oxide La2O3 on mechanical behaviour, wear resistance, and residual stress of AA6061-T6 hybrid composite fabricated via ultrasonic-assisted stir casting

This investigation involves the fabrication of an aluminium metal matrix composite using AA6061-T6 alloy as the matrix, incorporating 2 wt% of hard ceramic (TiB2, 14 μm particle size) and 0.5 wt% of rare earth oxide (La2O3, 40–50 nm particle size) reinforcement powders through ultrasonic assisted stir casting. The study examines the microstructure, residual stress, and mechanical properties alongside performing pin-on-disk wear tests. Taguchi's optimization and ANOVA are used to optimize the wear rate of the composite using three control parameters: Load, Sliding Distance, and Sliding Speed. Results from optical micrography and field emission scanning electron microscopy (FESEM) with energy-dispersive spectrometer (EDS) analysis confirm the uniform distribution of TiB2 and La2O3 particles within the AA6061-T6 volume when ultrasonic stirring is employed. The composite's microhardness is found to increase by 25.15 %, and its tensile strength by 31.32 % compared to the base alloy due to a higher dislocation density. ANOVA highlights Load as the primary influencer, contributing 69.54 %, followed by Sliding Distance (17.45 %) and Sliding Speed (12.56 %). The optimal parameters for minimizing wear rate are found to be Load (20 N), Sliding Distance (1500 m), and Sliding Speed (2.5 m/s). Scanning Electron Microscope (SEM) images of worn surfaces reveal various mechanisms such as abrasion, delamination, and adhesion, with abrasion being the dominant mechanism. Residual stress increases with the addition of TiB2 and La2O3 particles in the matrix, showing transitions from tensile to compressive stress from the inner to the outer surface of the composite casting.

Controlled Size Characterization Process for In-Situ TiB2 Particles from Al Matrix Composites Using Nanoparticle Size Analysis.

The wide size range and high tendency to agglomerate of in-situ TiB2 particles in reinforced Al matrix composites introduce great difficulties in their size characterization. In order to use a nanoparticle size analyzer (NSA) to obtain the precise size distribution of TiB2 particles, a controlled size characterization process has been explored. First, the extraction and drying processes for TiB2 particles were optimized. In the extraction process, alternated applications of magnetic stirring and normal ultrasound treatments were proven to accelerate the dissolution of the Al matrix in HCl solution. Furthermore, freeze-drying was found to minimize the agglomeration tendency among TiB2 particles, facilitating the acquisition of pure powders. Such powders were quantitatively made into an initial TiB2 suspension. Second, the chemical and physical dispersion technologies involved in initial TiB2 suspension were put into focus. Chemically, adding PEI (M.W. 10000) at a ratio of mPEI/mTiB2 = 1/30 into the initial suspension can greatly improve the degree of TiB2 dispersion. Physically, the optimum duration for high-energy ultrasound application to achieve TiB2 dispersion was 10 min. Overall, the corresponding underlying dispersion mechanisms were discussed in detail. With the combination of these chemical and physical dispersion specifications for TiB2 suspension, the bimodal size distribution of TiB2 was able to be characterized by NSA for the first time, and its number-average diameter was 111 ± 6 nm, which was reduced by 59.8% over the initial suspension. Indeed, the small-sized and large-sized peaks of the TiB2 particles characterized by NSA mostly match the results obtained from transmission electron microscopy and scanning electron microscopy, respectively.

Predicting the Quality of Grain Refiners from Electrical Resistance Measurements of Aluminum

The objective of grain refining is to reduce the size of the primary solidified crystal grains in aluminum alloys, thereby eliminating large columnar grains. Excellent grain refining results can be achieved only when the grain refining agent is of excellent quality, i.e., the number of Al3Ti and TiB2 particles must be appropriate, the shape and size distribution of the particles must be suitable, the Ti/B ratio must be appropriate, and so on. To evaluate the quality of grain refiners, the electric resistivity was measured on four different grain refiners. The obtained results were supported by differential scanning calorimetry analyses and microstructure analyses. It was found that the quality of a grain refiner can be assessed by measurements of electrical resistance. The lowest electrical resistivity was measured for grain refiner B (Al-3Ti-1B), which had the lowest impurity content and the most suitable number and size distribution of TiB2 and Al3Ti particles, as well as the most optimal Ti/B ratio, namely, 3.6. A larger number and size of TiB2 and Al3Ti particles, as well as elements such as Fe and Si, and also inclusions, which were also confirmed by DSC analyses, cause a higher electrical resistivity due to a stronger scattering of electrons through the matrix.

Finite element analysis on the formation, size and pattern of distribution of TiB2 in MMC

A 6 volumetric percentage of TiB2 reinforcement with A356 aluminium matrix is fabricated through in-situ process. The three pouring temperatures of 750 °C, 780 °C & 810 °C with ten min, twenty min and thirty min holding times. Six identical locations are selected from 24 locations based on pouring height of the ingot. Also, the direction of pouring the melt considered for fluidity and temperature distribution. This assessment is performed by using Procast software to permit for aluminium titanium di-boride metal matrix component, through in-situ formed with the favoured distribution of debris and with preferred length of reinforcement, at numerous positions of the solid issue. A finite element tool is used for analyse the formation of MMC and the pattern of distribution through the thermal analysis in various locations of the ingot. From the total curve graph of the heat transfer and distribution of the melt based on the turbulence and pouring height, the 810 °C shown good results. Also, the results is best suitable for aeronautical applications to replace the magnesium.

Microstructure and mechanical properties of in situ TiB2•TiAl3/2024Al composite subjected to multidirectional forging

The TiB2•TiAl3/2024Al composite fabricated by in situ reaction method was subjected to multidirectional forging (MDF) and the effects of temperature and pass number of MDF on the microstructure and mechanical properties of the composite were investigated. By increasing the MDF temperature (from 350 to 500 °C) or increasing the number of MDF passes (from 1 to 4 passes), the fraction of high-angle grain boundaries (HAGBs) increased, and the average grain size of the Al matrix decreased. The tensile strength and elongation of the composite improved with increasing MDF temperature and pass number. After 4 MDF passes at 450 °C, the average grain size of the composite decreased from 45.00 to 3.08 μm, and the tensile strength and elongation increased by 12.78% and 282.46%, respectively. During the MDF process, a great number of TiAl3 particles fractured, and the size of TiAl3 decreased. Meanwhile, the agglomeration of TiB2 particles reduced, and the clustering of TiB2 particles tended to elongate and directional alignment. Both discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) occurred during the MDF process, which had a close relationship with the size and distribution of TiB2 and TiAl3 particles. The improvement of strength caused by MDF processing for the studied composite was quantitatively analyzed by models of the strengthening mechanism. The calculated results indicate that the load transfer effect and thermal expansion mismatch effect may partially counteract the effects of grain refinement on the enhancement of strength.

Manufacturing of (Al–10Zn) / TiB2 in-situ nanocomposites by reactive liquid metallurgy and hot-extrusion for enhanced interfacial bonding and mechanical properties

This work systematically deals with the development of an (Al–10Zn) die-casting alloy reinforced with in-situ synthesized hexagonal-shaped TiB2 nano-rods through casting and hot-extrusion processes. The cast specimens were extruded at 673 K with an extrusion ratio of 2:1 to orient the micro-texture, generate sub-grains within grains, reorder the reinforced in-situ TiB2 nanoparticles in the matrix, and engender strain fields to improve the mechanical properties. The nanoscale hexagonal TiB2 nano-rods (∼89 nm length and 14 nm edge) were synthesized by the chemical reaction of two halide salts (K2TiF6 and KBF4) with (Al–10Zn). The fabricated AMNCs were characterized using diffracted beams (XRD), scattered beams (FESEM and EBSD) and transmitted beams (TEM) received from the specimen. The diffracted beams from the X-rays reveal the formation of a TiB2 phase with a major α-Al phase and an individual Zn phase. The scattered beams from FESEM and EBSD revealed the homogenous distribution of TiB2 with less particle-free spacing, refinement of grains to an ultrafine level, and the absence of imperfections such as voids and interfacial de-bonding. The strain fields were observed through transmitted beams in the TEM analysis which were engendered by the thermal misfit between the matrix and TiB2 reinforcement. Among the fabricated AMNCs, (Al–10Zn) + 6 wt% TiB2 nanocomposite exhibited higher mechanical strength (160 MPa UTS) whereas (Al–10Zn) + 4.5 wt% TiB2 nanocomposite retained the ductility with improved strength (151.7 MPa UTS and 40% elongation). The strengthening mechanisms were computed using the (a) Zheng and Chen model and (b) Modified Cylne model to estimate the contribution of individual strengthening, and compared with the experimental results. The grain size strengthening contributed more to the total strength owing to the Zener pinning effect by in-situ TiB2 nano-rods.

Experimental Investigation to Confirm the Presence of TiB2 Reinforcements in the Matrix and Effect of Artificial Aging on Hardness and Tensile Properties of Stir-Cast LM4-TiB2 Composite

The present work focuses on the effect of multistage solution heat treatment (MSHT) and artificial aging on two-stage stir-cast LM4 + TiB2 (1, 2, and 3 wt.%) composites on the mechanical properties as compared to as-cast and single-stage solution heat-treated (SSHT) composites. Two novel tests, viz. the confirmation hardness test and the chemical analysis test, were performed to ensure the soundness of the casting and uniform distribution of TiB2 within the matrix. Samples subjected to MSHT + aging at 100–200 °C displayed the highest hardness and UTS values compared to as-cast and SSHT + aging at 100–200 °C samples. Compared to as-cast alloy, peak-aged samples of 1–3 wt.% (MSHT + aging at 100 °C), hardness values improved from 107–150%, and UTS values improved from 47–68%. The presence of metastable phases (θ′-Al2Cu and θ″-Al3Cu) and of hard TiB2 particles are the reason for the improvement in the properties. Peak aged LM4 + 3 wt.% TiB2 composite displayed the highest hardness of 175 VHN and UTS of 251 MPa. Fracture analysis of the LM4 alloy showed dimple rupture, and its composites revealed quasi-cleavage fracture. Based on the overall results, the inclusion of TiB2, MSHT, and artificial aging treatment on the LM4 alloy significantly influenced the composites’ mechanical properties.

Selective laser melting of TiB2/AlSi10Mg composite: Processability, microstructure and fracture behavior

Recently aluminum matrix composites (AMCs) manufactured by selective laser melting (SLM) have attracted extensive attention in the lightweight application fields. In this work, pre-alloyed 6.5 wt.% TiB 2 /AlSi10Mg composite powder was initially densified via SLM. The result indicated that the material had a wide processing window, and the fully dense bulked samples were successfully fabricated when the laser volumetric energy density is 50–70 J/mm 3 . We concluded that the morphology, size, and distribution of TiB 2 particles in the as-deposited condition were generally consistent with those of the powder. The fine equiaxed microstructures without apparent anisotropy were remarkably realized. Therefore, a superior combination of excellent tensile strength and elongation was evident in the horizontal (∼536.9 MPa and ∼16.5 %) and vertical (∼517.3 MPa and ∼15.4 %) directions due to the systematic processing optimization, accompany with the strong work hardening capability. Its tensile properties are higher than that of the reported SLM-ed matrix alloy and other particle-reinforced Al-Si composites. Besides, the fracture behaviors were complicated, and the crack propagation paths were affected not only by the defect and eutectic Al-Si of the molten pool boundary (MPB) but also by the homogeneously distributed TiB 2 particles. This study is expected to establish an important guiding significance for the practical engineering application of SLM-ed in-suit TiB 2 /AlSi10Mg composite.

Integrated model for describing the microstructure evolution of the inoculated Al-Zn-Mg-Cu alloys in continuous solidification

An integrated model based on the population dynamics approach and the cellular automaton method has been developed to simulate the solidification process of the Al-Zn-Mg-Cu alloys. The nucleation, spherical growth/dissolving and dendritic growth of the α-Al nuclei/grains are taken into account. The model is validated by comparing with the experimental results firstly, and then is applied to calculate the details of the microstructure formation in Al-Zn-Mg-Cu alloys inoculated with Al-5Ti-1B master alloys. The effects of the size distribution of TiB2 and the solidification conditions on the grain size are investigated. At last, an empirical formula for predicting grain size has been put forward based on the numerical calculations. The formula gives the dependent relationship between the grain size, the cooling rate of melt, the additive amount of refiner, the composition of the solutes and the size distribution of TiB2 particles.

Numerical simulation of the melting and alloying processes of elemental titanium and boron powders using selective laser alloying

Abstract Titanium Diboride (TiB2) has excellent performances in terms of hardness, mechanical strength, wear resistance, and corrosion resistance, but its application is still limited due to its poor manufacturability. Selective Laser Additive Manufacturing using elemental powders of Titanium and Boron provides a transforming technology for the application of TiB2 by enabling its 3D free forming capability. In this paper, to investigate the joint effects of selective laser melting and chemical reactions in the Selective Laser Alloying (SLA) process, a numerical based simulation was conducted using COMSOL Multiphysics 5.4. This is the first successful numerical study of melting and reaction in the selective laser alloying process providing details about the molten pool. The influences of the evolution of free solid-liquid interface, species transport, the chemical reaction rate, and the evaporation latent heat were discussed by considering the production of TiB2 and its concentration distribution in the computational domain. The simulation results show that the melting front of the free surface has a relatively high velocity, at the instant when the powder particles melt, the first speed jump will occur, and when the reaction is triggered, the second speed jump will occur; the heat released from the exothermic reaction between Titanium and Boron is an important energy source which can reduce the energy input and help improve the manufacturing efficiency of the SLA process; the evaporation latent heat also has a significant influence to the temperature field in the computational domain; the concentration distribution of TiB2 strongly relies on the chemical reaction rate and the diffusion coefficient. This study may blueprint a design strategy for the Additive Manufacturing research community by considering to adopt the proposed numerical model, predict the reactions and species concentration, and explore the structures of microscale molten pool and the macroscale defects or so.

Effect of TiB2 addition on the microstructural, electrical, and mechanical behavior of Cu–TiB2 composites processed via spark plasma sintering

Abstract In this investigation, copper–TiB2 metal matrix composites were fabricated by spark plasma sintering. The effect of TiB2 (2.5, 5, 7.5, and 10 wt.%) additions on the microstructural, electrical, and mechanical properties of the composites was investigated. There was a remarkable reduction in processing time and temperature by this process as compared to conventional sintering. Scanning electron microscopy with energy dispersive X-ray spectroscopy elemental maps revealed a homogeneous distribution of TiB2 in the copper matrix. The hardness of the composites exhibited no consistent trend with the addition of TiB2. An improvement in tensile strength was observed at the expense of ductility. Electrical conductivity showed a decreasing trend. Morphology of the fracture surfaces was analyzed to predict the nature of failure under tensile load.

Abrasive Wear Behaviour of TiB2 Reinforced In-Situ Synthesized Magnesium RZ5 Alloy based Metal Matrix Composites

Abrasive wear behaviour of TiB2 reinforced in-situ magnesium RZ5 alloy-based metal matrix composites was investigated using a pin-on-disc wear testing apparatus. The in-situ RZ5/TiB2 composite was synthesized through the self-propagating high-temperature synthesis route. The microstructure of the composite revealed a near-uniform distribution of TiB2 in magnesium matrix. The abrasive wear behaviour on the base RZ5 alloy and TiB2 reinforced composites were investigated in terms of weight loss and co-efficient of friction. The effect of varying applied load (10–30 N), sliding distance (1000–3000 m), and wt% of TiB2 content on abrasive wear properties were analysed. The results indicated a higher wear loss of the materials with increase in the applied load and sliding distance. Co-efficient of friction decreased with increase in the applied load but increased with increase in sliding distance. The morphology of the worn surface under different test conditions was analysed in terms of delamination, wear groove, oxide, and wear debris formation using field emission scanning electron microscope. Large flaky shape wear debris was noticed when the load applied is 30 N whereas equiaxed wear debris was noticed when the applied load is 10 N. Increase in sliding distance increased the contact temperature led to the formation of the oxide layer on the contact surface.

Effect of Particle Size Distribution on Microstructure and Mechanical Properties of TiB2-SiC-Si Composites

TiB2-SiC-Si ceramic composites were fabricated based on molten silicon infiltration method. The influence of particle size distribution of TiB2 on the microstructure and mechanical properties of TiB2-SiC-Si ceramic composites was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron universal testing machines, etc. The results showed that the composite consisted of TiB2, SiC and Si phases. The microstructure analysis showed that: the content of residual Si could be controlled less than 16 vol.% in the composite by particle size distribution. When the particle size distribution of TiB2 was 42:32:26, the TiB2-SiC-Si composite showed the optimum properties. The open porosity, volume density, Vickers-hardness, flexural strength and fracture toughness were 0.51%, 3.63 g/cm3, 17 GPa, 275 MPa and 5.7 MPa·m1/2, respectively.

Wear Resistance of Pre-ECAP Annealing A356 Al Alloy with 1.5 Wt.% TiB2

The combination of heat treatment, addition of grain refiner and ECAP processing is used to improve mechanical properties and wear resistance of A356 Al alloys with 1.5 wt.% TiB2. The alloys were grouped into as-cast and pre-ECAP annealing. The alloys were characterized with hardness and wear testing, optical microscopy and SEM. The ECAP processing was done through BA route for 4 passes and it improved hardness, distribution of TiB2 and Si particles in the aluminium matrix and increased wear resitance of pre-ECAP annealing specimen.

Synthesis of Al LM25/TiB2 in-situ composites and investigation of its adhesive wear behavior

Aluminum/titanium diboride (TiB2) in-situ metal matrix composite was produced by reaction between aluminum alloy and potassium hexafluoro titanate (K2TiF6) and potassium tetrafluoro borate (KBF4) salts. Aluminum titanate and aluminum diboride formed during reaction process resulted in formation of TiB2. Energy Dispersive X-Ray analysis was carried out in order to confirm the presence of titanium and boron. Microstructure analysis of composite specimen showed uniform distribution of TiB2 in aluminum matrix. The composite was tested for sliding wear behavior using pin-on-disc tribometer by considering load (10N, 20N, 30N), sliding velocity (1.5m/s, 2.5m/s, 3.5m/s) and distance (750 m, 1250m, 1750m) as parameters. A Taguchi’s L27 orthogonal array was used to optimize process parameters to obtain maximum wear resistance. Analysis of Variance technique was used for statistical analysis for finding parameters having maximum significance with respect to wear rate and Signal-to-Noise ratio was employed to determine their level of influence. Results clearly concluded that load (69.23%) has primary effect on wear rate followed by sliding distance and velocity. Regression model was developed to find relation between wear rate and process parameters. Confirmation tests were conducted and percentage error was found to be less than 10. Scanning Electron Microscopic studies carried out on worn surfaces revealed severe delamination at high loads.

Metallurgical features of direct laser-deposited Ti6Al4V with trace boron

The variation in the metallurgical characteristics, in terms of microstructure and microhardness, of direct laser deposited Ti6Al4V premixed with trace boron (0.04 wt%) was investigated. A significant improvement in the clad hardness from 390 to 450 HV in Ti6Al4V deposit to 510–600 HV in Ti6Al4V0.04B clad was observed. This was attributed to not only the fine α-Ti laths but also the presence of very hard TiB precipitates formed in the latter sample when compared to the martensitic α′-Ti formed in the former specimen. The high cooling rates experienced during deposition produced an extremely fine and even distribution of TiB.

Effect of TiB2 nano-inclusions on the thermoelectric properties of boron rich boron carbide

Boron carbide has exceptional thermoelectric properties due to its unique crystal structure. The effects of nano-TiB2 inclusions on the thermoelectric properties of boron rich boron carbide is presented here. Boron rich boron carbide-TiB2 composites were prepared in-situ by sintering of wet ball milled B, B4C and nano-TiO2 powders through Spark Plasma Sintering (SPS) at 1900 °C under 50 MPa pressure. Five different compositions of the composite were prepared- with 1, 2.5, 5, 7.5 and 10 wt.% TiO2. The dependence of densification and thermoelectric properties on TiO2 content were studied. The microstructure was observed through Field Emission Scanning Electron Microscope (FESEM) and phases were analyzed using X-ray diffraction (XRD). Relative densities of 94.8% to 99. 3% were obtained and an almost homogeneous distribution of TiB2 was observed. The electrical property was found to be high for sample with 1 wt% TiO2 and reduced subsequently with higher wt% of TiO2. The overall dimensionless figure of merit was found to be higher than B4C-TiB2 composites, due to the formation of boron rich phase but the effect of TiO2 was not significant. The increase in lattice parameter of boron carbide phase for different TiO2 amounts added showed that the final composition of the composite depends on the amount of TiO2 added.

Effect of Hybrid Reinforcements on the Microstructure and Mechanical Properties of Ti-5Al-5Mo-5V-Fe-Cr Titanium Alloy

In order to investigate the different effects of trace TiB and TiC on the microstructure and the mechanical properties of Ti-5Al-5Mo-5V-1Fe-1Cr Ti alloy, two different modified Ti-5Al-5Mo-5V-1Fe-1Cr Ti alloys are fabricated via a consumable vacuum arc-remelting furnace in this work. Though the volume fractions of the reinforcements are the same in the two alloys, the molar ratio of short fibers to particles is different. The materials are subjected to thermomechanical processing and heat treatment. The effects of TiB short fibers and TiC particles on the spheroidization of α phase or the refinement of β phase have no obvious difference during heat treatment. Subsequently, the room temperature tensile test is carried out. The area covered by the σ-ε curve of the tensile test is used to compare toughness. It is revealed that the refinement of the β phase and the load bearing of TiB play key roles in promoting the toughness of the alloys. TiB tends to parallel the external load during tensile tests. The distribution of TiB also changes during isothermal compression test. Owing to the competition of dynamic softening with dynamic hardening, the length direction of TiB tends to parallel to the direction of maximum shear stress during the compression, which makes TiB play the role of load bearing better.

Investigating the microstructure and mechanical properties of Al-TiB2 composite fabricated by Friction Stir Processing (FSP)

Microstructure and mechanical properties of Al-TiB2 composite fabricated by Friction Stir Processing (FSP) were evaluated. In situ TiB2-10wt%Al composite powder was synthesized by mechanical alloying (MA) of Ti, B and Al powder mixture. FSP was applied on AA6063 with and without the addition of TiB2-Al composite powder. Microstructural evaluations showed a nearly uniform distribution of TiB2 in aluminum matrix after FSP with the addition of composite powder. FSP of AA6063 alloy without the addition of reinforcing particles resulted in slight improvement in tensile strength to about 195MPa in comparison to the as-received alloy. By the addition of MAed TiB2-Al composite powder during FSP the tensile strength could increase to about 280MPa which was about 70% higher than that of the base material.

Microstructure and properties of TiB2–TiB reinforced titanium matrix composite coating by laser cladding

TiB2 particle and TiB short fiber reinforced titanium matrix composite coatings were prepared utilizing in situ synthesized technique by laser cladding on the surface of Ti6Al4V alloy. Through the experiment, it was found that the surface of the single-track coatings appeared in the depression, but it can be improved by laser track overlapping. With the increase of laser power density, the amount of TiB short fiber was increased, and the distribution of TiB2 and TiB became more uniform from the top to bottom. The micro-hardness of TiB2/TiB coating showed a gradient decreasing trend, and the average micro-hardness of the coatings was two-fold higher than that of the substrate. Due to the strengthening effect of TiB2 particle and TiB short fiber, the wear volume loss of the center of the coating was approximately 30% less than that of the Ti–6Al–4V substrate, and the wear mechanism of the coating was mild fatigue particle detachment.