TiB2 Reinforcement Research Articles

Microstructure and Electrochemical Behaviour of TiB2 Reinforced Titanium Matrix Composites Fabricated by Spark Plasma Sintering in Simulated Body Fluid Environment

Titanium and its alloys are one of the most highly used metallic materials in modern materials engineering; its use range from aerospace, defence, and biomedical applications. However, this material has relatively poor corrosion resistance in biomedical applications; this is due to aggressive anodic ions present in physiological fluids. In this study, powder metallurgical processes were employed to enhance the properties of titanium through the dispersion of TiB₂ ceramic particulates into the matrix. The consolidation of the admixed powders was carried out using spark plasma sintering (SPS).

On the Study of a TiB<sub>2</sub> Nanoparticle Reinforced 7075Al Composite with High Tensile Strength and Unprecedented Ductility

Strength and ductility are the two most important mechanical properties of a structural material. However, they are often mutually exclusive. In this study, a 6 wt. % TiB2 nanoparticle reinforced 7075Al (i.e. TiB2/7075Al) composite was designed and produced by the processing route combining casting, friction stir processing, hot extrusion and T6 heat treatment. The result of tensile testing demonstrates that the as-processed composite sample presents an ultimate tensile strength of 677 MPa and a total elongation to failure of around 15 %, being higher than any Al or Al based materials ever reported. The typical microstructure contains the TiB2 reinforcement nanoparticles uniformly distributed in the equiaxed Al grain matrix (2 μm in average grain size). In addition to the dispersed nanoprecipitates of the 7075Al (Al-Zn-Mg-Cu) matrix, the integrated TiB2 nanoparticles are systematically decorated by a shell corresponding to (Zn1.5Cu0.5)Mg. This finding challenges our understanding and opens a door for further enhancing strength and ductility being easily scalable for industrial applications.

Microstructure evolution and its effect on mechanical response of the multi-phase reinforced Ti-based composites by laser powder-bed fusion

The Ti-based composites reinforced by in-situ formed TiB and TiC particles were successfully produced by laser powder-bed fusion (LPBF) additive manufactured technology using a B4C/Ti composite powder mixture, in order to further enhance the mechanical properties of commercially pure titanium (CP-Ti). The effects of applied laser energy density on the microstructure and attendant mechanical properties of the LPBF-processed parts were investigated, and meanwhile, the underlying formation mechanisms of the TiB and TiC particles by LPBF were elucidated. It showed that the whisker-like TiB and near-granular TiC reinforcements were in-situ formed through a laser-induced reaction of Ti-B4C system via a diffusion-nucleation-growth mechanism from the melt. The in-situ reinforcements arranged from dendrite to cellular morphology were primarily determined by the thermal convections that transformed from dendrite to annular patterns as a result of the great elevation of temperature gradient between molten Ti liquid and heated B4C particles as an increase in the applied laser energy density. The tensile tests revealed that the LPBF-ed Ti-based composites possessed an enhanced tensile strength from 893 ± 5 MPa to 1211 ± 8 MPa and a slightly reduced elongation from 18.1% to 16.8% with the transition of typically fracture morphologies from elongated dimples to equiaxed-ultrafine dimples, respectively, attributed to the combined grain refinement and microstructure strengthening effects.

Microstructure and mechanical properties of TiB2-reinforced 7075 aluminum matrix composites fabricated by laser melting deposition

In this study, we adopt laser-melting deposition (LMD) technology to fabricate TiB2/7075 aluminum matrix composites (AMCs), and we investigate in detail the effect of the TiB2 content on the microstructure, nano-hardness, compressive properties, and wear performance. We prepare experimental samples by using a laser power of 800 W and a velocity of 0.01 m/s, and the results are evaluated. It was observed that the reinforcement particles dispersed irregularly throughout the Al matrix as the TiB2 contents increased. The grain size of the fine-grain zone decreased appreciably by 31.9% from 8.41 µm (LMD sample without TiB2 reinforcement) to 5.73 µm. Furthermore, the AMCs with 4 wt% reinforcement exhibited impressive mechanical properties, i.e., nanohardness of 1.939 Gpa, compressive strength of 734.8 MPa, and a wear rate of 1.889 × 10−4 mm3/Nm. The wear resistance improved and the wear mechanism changed from adhesive wear to debris wear with the addition of TiB2 reinforcement.

Enhancement of Mechanical properties of AlSi5Cu3 Aluminum alloy using TiB2 reinforcements

In present investigation, ex situ composite of AlSi5Cu3 aluminum alloy reinforced through TiB2 reinforcement particles has been developed. Different weight percentage of TiB2 particles were incorporated in liquid melt via stir casting method. Combine effect of stirrer speed (500,700 rpm), and weight percentage (1, 2, 3) TiB2 particle on mechanical properties were studied. Microstructural study has been carried out using optical microscopy and SEM analysis, which shows homogeneous distribution of particles and improvement in grain size compare to aluminum alloy AlSi5Cu3. Presence of TiB2 was confirmed using XRD analysis. Improvement in tensile strength and hardness was observed due to homogeneous distribution of particles.

Microstructure and mechanical property of TiB reinforced Ti matrix composites fabricated by ultrasonic vibration-assisted laser engineered net shaping

PurposeThe purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal weaknesses such as porosity, coarse primary TiB whisker and heterogeneous distribution of TiB reinforcement in the LENS-fabricated TiB reinforced Ti matrix composites (TiB-TMC) parts.Design/methodology/approachAn experimental investigation is performed to achieve the results for comparative studies under different fabrication conditions through quantitative data analysis. An approach of microstructural characterization and mechanical testing is conducted to obtain the output attributes. In addition, the theoretical analysis of the physics of ultrasonic vibration in the melting materials is presented to explain the influences of ultrasonic vibration on the microstructural evolution occurred in the part fabrication.FindingsBecause of the nonlinear effects of acoustic streaming and cavitation induced by ultrasonic vibration, porosity is significantly reduced and a relatively small variation of pore sizes is achieved. Ultrasonic vibration also causes the formation of smaller TiB whiskers that distribute along grain boundaries with a homogeneous dispersion. Additionally, a quasi-continuous network (QCN) microstructure is considerably finer than that produced by LENS process without ultrasonic vibration. The refinements of both reinforcing TiB whiskers and QCN microstructural grains further improve the microhardness of TiB-TMC parts.Originality/valueThe novel ultrasonic vibration-assisted (UV-A) LENS process of TiB-TMC is conducted in this work for the first time to improve the process performance and part quality.

Microstructure evolution and properties of in situ synthesized TiB2-reinforced aluminum alloy by laser surface alloying

Abstract

A novel spark plasma sintering route to process high-strength Ti–4Al–2Fe/TiB nano-composite

ABSTRACTTi–4Al–2Fe alloy and Ti–4Al–2Fe/TiB nano-composite were processed by a novel spark plasma sintering route. KBF4 was used as an alternative and inexpensive boron precursor to form TiB reinforcement in situ during sintering. Fe was used as an alternative to vanadium to make the (α + β) Ti matrix. The processed Ti–4Al–2Fe alloy exhibited excellent mechanical properties (CS = 1798 MPa). The TiB whiskers were distributed homogeneously and were fine (widths 130 nm and lengths from 100 nm to 3 µm). No residual TiB2 was found in the composite, in contrast with other methods. The TiB homogenised and refined the microstructure, while the hardness (710 HV), compressive strength (2414 MPa) and elastic modulus (140 GPa) all increased significantly when compared to the unreinforced alloy.

Deformation behavior and processing map development of AZ91 Mg alloy with and without addition of hybrid in-situ TiC+TiB2 reinforcement

Magnesium matrix in-situ composites with hybrid TiC+TiB2 reinforcement are potential materials for automobile and aerospace applications. It is essential to establish the processing map of such composites as these materials may undergo several thermo-mechanical processes while manufacturing engineering components. In the current work, AZ91 Magnesium matrix TiC+TiB2 reinforces hybrid in-situ along with its base counterpart were developed and subjected to solutionization followed by peak aging treatment. The safe processing zone for both base and in-situ composite at all heat treatment conditions have been established through processing map based on dynamic materials model (DMM) by conducting hot compression tests at various temperatures (250 °C – 450 °C) and strain rates (0.001 s−1 – 10 s−1). Two regions: stable and instable were identified from processing map for all the material conditions. Dynamic recrystallization is the main dominant mechanism in stable region, whereas instable region is characterized by twin and intergranular cracks. To understand the mechanism of hot deformation behavior, activation energy is calculated based on constitutive model for all material conditions. The developed in-situ composite in peak aged condition is found to possess higher activation energy (∼230 kJ/mol) as compared to base alloy (∼126 kJ/mol). A correlation between constitutive model and processing map have been established with an emphasis on their microstructures.

In-situ preparation and formation of TiB/Ti-6Al-4V nanocomposite via laser additive manufacturing: Microstructure evolution and tribological behavior

In this study, the in-situ synthesized TiB/Ti-6Al-4Vceramic-matrix nanocomposites with greatly enhanced hardness and wear resistant property have been prepared via selective laser melting (SLM) using a simple mixture of microsized Ti-6Al-4V and TiB2 powders. In order to provide a valuable reference for fabricating TiB/Ti-6Al-4V parts with metallographic features, effects of reinforcement content on microstructure and mechanical properties have been systematically investigated. It is found that during SLM process, the additive particles TiB2 are totally transformed into need-like nanoscaled TiB phase, and the microstructure of composites is composed of mutual parallel strips architecture with TiB rich in some regions but lean in the other regions. The SLM-producedTiB/Ti-6Al-4 V composites exhibit superior nanohardness of 6.0 GPa, which is much higher than its traditional sintering counterpart. Moreover, the in-site synthesized TiB reinforcement can remarkably improve in the wear resistance properties, the wear loss of TiB-free sample is approximately 2 times than that of the sample with 3 wt% TiB2.

On the Formation and Distribution of In Situ Synthesized TiB2 Reinforcements in Cast Aluminium Matrix Composites

Introduction of TiB2 reinforcements into aluminium matrices allows composites to be obtained that exhibit excellent mechanical properties and good wear and corrosion resistance. These composites find applications in the automotive, aerospace and marine industries. In the present work, the in situ synthesis of ultrafine TiB2 particulates in an aluminium matrix was accomplished by reaction synthesis of TiB2 using K2TiF6 and KBF4 (in 120% excess to the stoichiometrically needed) fluxes in pre-melted aluminium. Composites were prepared with different concentrations of TiB2 in (2.5, 5 and 10 wt %) in an aluminium matrix. The holding time of the molten composite in an induction furnace was varied from 10 min to 50 min. The in situ formation of TiB2 reinforcement and its distribution in cast aluminiummatrix composites was analyzed based on microstructural studies, microhardness measurements and wear tests. The exothermic reaction between the halide fluxes starts after 10 min of holding time and completes before 20 min of holding time. The dominant phase was TiB2 after 20 min of holding time, while the formation of Ti3B4 was observed as the holding time was extended. The distribution of the reinforcing phases was studied by analyzing the scanning electron microscopy (SEM) images. An optimum holding time (20 min) of the composite melt was determined based on the dominant wear mechanism, microhardness, and phase composition of the composites.

Fabrication of AA7005/TiB2-B4C surface composite by friction stir processing: Evaluation of ballistic behaviour

The present work aims to enhance the ballistic resistance of AA7005 alloy by incorporating the TiB2 and B4C ceramic reinforcement particles. Surface composites with different weight fractions of TiB2 and B4C particles were processed by friction stir processing. Micro-hardness and depth of penetration tests were carried out to evaluate the ballistic properties of the surface composites. The surface hardness of the composite was found to be nearly 70 HV higher than base alloy. The depth of penetration of the steel projectile was 20–26 mm in the composites as compared to 37 mm in the base alloy. Ballistic mass efficiency factor of the surface composite was found to be 1.6 times higher than base alloy. This is mainly attributed to the dispersion strengthening from the reinforcement particles.

Two-scale TiB/Ti64 composite coating fabricated by two-step process

In order to improve the hardness and wear resistance of Ti materials, TiB/Ti64 composite coatings were synthesized by two-step method. Microstructure analysis reveals that a dense composite layer reinforced by two-scale TiB and well bonded with substrate was synthesized, and the coarse primary TiB prism (width: 7–17.5 μm) and fine eutectic TiB whisker (width: 0.3–1.2 μm) were free of reinforcement/matrix interfacial chemical reaction. Consequently, the hardness of the composite coating was significantly improved by two-scale TiB reinforcements, self-joining structures and strong reinforcement/matrix interface. Nanoindentation tests indicate that coarse primary TiB zone exhibited superior hardness, modulus and wear resistance, which was more beneficial to enhancing the coating performance. Besides, the hardness increased with the increasing TiB content and decreased with the increasing heat input, and the maximum hardness (HRC 60) was obtained by employing 29.4 wt.%TiB2+Ti64 powders and cladding at 162.7 J mm−1, which is 80.2% higher than that of substrate (HRC 33.3). Meanwhile, the friction coefficient of the composite coating (0.14) was also significantly decreased compared with that of substrate (0.40).

Flow behavior and microstructure evolution of a TiBw/TA15 composite with network-distributed reinforcements during interrupted hot compression

Interrupted hot compression tests were performed on a TiBw/TA15 composite with network architecture to study its flow behavior and microstructure evolution during a two-step deformation process. The microstructure was observed by electron backscatter diffraction (EBSD) and the high-temperature β grain boundaries were reconstructed through several special misorientation angles. The fraction of the primary α (αp) phase declined during the heat preservation process. The flow stress exhibited a lower value due to softening upon reloading compared to that observed prior to the interruption. In addition, the hold time and deformation temperature were important factors influencing the composition of the matrix phase, and the αp phase disappeared with increasing hold time and temperature. The high-temperature β grains became longer with a larger average aspect ratio when the deformation temperature reached 1283 K. Both TiB reinforcement and the αp phase restrained the growth of β grains, preventing hot deformation at higher temperatures and resulting in longer inter-pass holding times due to the absence of the αp phase. The low strain rates resulted in a significant β phase grain growth because of sufficient time and the lack of constraints. The optimized process parameters, which can provide guidance to actual production, were obtained in this study.

Cycle oxidation behavior and anti-oxidation mechanism of hot-dipped aluminum coating on TiBw/Ti6Al4V composites with network microstructure

Controlled and compacted TiAl3 coating was successfully fabricated on the network structured TiBw/Ti6Al4V composites by hot-dipping aluminum and subsequent interdiffusion treatment. The network structure of the composites was inherited to the TiAl3 coating, which effectively reduces the thermal stress and avoids the cracks appeared in the coating. Moreover, TiB reinforcements could pin the TiAl3 coating which can effectively improve the bonding strength between the coating and composite substrate. The cycle oxidation behavior of the network structured coating on 873 K, 973 K and 1073 K for 100 h were investigated. The results showed the coating can remarkably improve the high temperature oxidation resistance of the TiBw/Ti6Al4V composites. The network structure was also inherited to the Al2O3 oxide scale, which effectively decreases the tendency of cracking even spalling about the oxide scale. Certainly, no crack was observed in the coating after long-term oxidation due to the division effect of network structured coating and pinning effect of TiB reinforcements. Interfacial reaction between the coating and the composite substrate occurred and a bilayer structure of TiAl/TiAl2 formed next to the substrate after oxidation at 973 K and 1073 K. The anti-oxidation mechanism of the network structured coating was also discussed.

Optimizationof Process Parameters of Copper Composites Produced via Friction Stir Processing

Increasing demands for operating properties of fabricated elements on one hand, and a necessity of reducing mass of a structure on the other, triggers materials engineering research into producing surface layers representing required functional properties. Methods commonly used in the production of surface layers, such as surfacing, spraying or re-melting with a laser beam have been known for years. A new method is the friction stir processing (FSP) of surface layers. The FSP process is primarily used for the modification of microstructure in near-surface layers of processed metallic components this deformation is produced by forcibly inserting a non-consumable tool into the workpiece, and revolving the tool in a stirring motion as it is pushed laterally through the workpiece. This is promising process for the automotive and aerospace industries where new material will need to be developed to improve resistance to wear, creep, and fatigue. The main objective of this project is to be producing copper reinforced metal matrix composite layers using micro sized TiB2 particles via friction stir processing (FSP) in order to enhance surface mechanical properties. Taguchi method was used to optimize these factors for maximizing the mechanical properties of surface composites. The fabricated surface composites were examined by optical microscope (OM) and scanning electron microscopy (SEM) for dispersion reinforcement particles. It was found that TiB2 particles are uniformly dispersed in the stir zone. Mechanical properties like tensile, Impact, hardness, were also evaluated. The results showed that functional characteristics of surface composites increased with the increase in vol. % of the micro sized TiB2 reinforcement particles. The observed mechanical properties are correlated with microstructure and fracture features.

A novel functionally gradient Ti/TiB/TiC hybrid composite with wear resistant surface layer

Ti/TiB/TiC hybrid composite was processed by a novel one-step in-situ process using spark plasma sintering (SPS). KBF4, which was used as a boron precursor for the first time, reacted with Ti to form the TiB reinforcement insitu. Graphite foils were used on either side of the compact as a carbon source to produce TiC during sintering. Ti reacted with carbon and formed TiC on both the surfaces of the composite. The thickness of the TiC layer was found to be ∼50 μm. The microstructure of the composite was graded with ultrafine TiC on top, fine needles of TiB near the surface and coarser TiB whisker reinforced Ti (Ti-4Al-2Fe/TiBw) in the bulk. The grain size of Ti also varied from 1 μm near the surface to 12 μm in the bulk. The surface layer exhibited very high hardness to the tune of 20 GPa compared to 7 GPa of the bulk Ti-4Al-2Fe/TiB composite. The functionally gradient composite exhibited only mild wear with wear rate that was almost one order of magnitude lower than that of the bulk Ti-4Al-2Fe/TiBw composite. While there were abrasive grooves formed on the Ti-4Al-2Fe/TiB bulk composite, the hybrid composite showed almost nil wear damage under the same test conditions. The surface TiC layer thus acted as an effective protection against wear and tear.

Tribological Properties of Nano TiB2 particle Reinforced 6061-T6 Aluminum Alloy Surface Composites via Friction stir processing

This research work is emphasized on the fabrication of nano Titanium Boride (TiB2) particle reinforced 6061-T6 Aluminum Alloy surface composites via Friction stir processing (FSP). Influence of volume percentage of nano sized TiB2 (average size is 35 nm) reinforcement particles on tribological properties and microstructural characterization of 6061-T6 Aluminum alloy based surface nano composite fabricated via FSP was studied. The fabricated surface composites have been examined by optical microscope (OM) and scanning electron microscope (SEM) for dispersion of reinforcement particles, thickness of nano composite layer formed on the Aluminum alloy substrate and wear morphology. The friction stirred zones were characteristically about the size of the rotating pin that is width and depth of 8 mm and 4 mm respectively.The depth of surface nano composite layer is measured as 3683.82 µm along the cross section of stir zone of surface nano composite normal to the FSP direction. Microstructures of all the surface composites are revealed that the distribution of reinforcement particles in the nugget zone (NZ). It is observed that increase in the volume percentage of TiB2 reinforcement particle, the microhardness was increased up to 132 Hv and this value is higher than the as received Aluminum alloy’s microhardness (104 Hv). It is found that high wear resistance exhibited at 4 volume percentage (vol.%) as compared with the 2 and 8 vol.%. The observed tribological properties were correlated with microstructure and wear morphology.

Dry Sliding Wear Behaviour Of AA6082-5%SiC AND AA6082-5%TiB2 Metal Matrix Composites

In the present work, dry sliding wear behavior of AA6082-5%SiC and AA6082-5%TiB2 metal matrix composites processed through the stir casting method was studied. Using Design of experiment software, the experiments were planned and conducted at 10–50N applied load and 200–1400 rpm rotational speed. The wear behavior was studied for metal matrix composites which are prepared according to specific dimensions using a pin- on- disc tribometer at room temperature. Process parameters: Applied load and rotational speed are considered to study the effect on the wear are plotted. It is observed that the effect of process parameters on mass loss on both the composites was found to be different. Optical microscopy studies reveal the presence of both adhesive and abrasive wear mechanisms due to the hard SiC and TiB2 reinforcement particles.

Microstructural characterization and mechanical properties of TiB2 reinforced Al6061 matrix composites produced using stir casting process

Particulate reinforced aluminum matrix composites are the most promising alternative for applications where the combination of high strength and ductility is essential. In the present study, Al-TiB2 composites with different amounts of reinforcement (3, 6 and 9wt%) were fabricated using stir casting method. after optimizing the process parameters such as preheating temperature, stirring speed and duration. Microstructure, mechanical properties and the fracture surfaces of tensile specimens were studied. Optical microstructure of prepared composites showed a uniform distribution of reinforcements in matrix and also SEM analysis demonstrated the strong bonding between matrix and reinforcements which is the consequence of improved wettability due to K2TiF6 addition and preheating of TiB2 powder before adding to the melt. In addition to microstructure uniformity, the tensile strength of composites was improved with increasing the volume fraction of TiB2 reinforcement particles without any significant decrease in elongation. SEM micrographs from fractured surfaces of tensile specimens approved that the ductile fracture is occurred in Al6061 alloy in all of prepared composites through nucleation and coalescence of micro-voids.