TiB2 Phases Research Articles

Prediction of macroscopic effective elastic modulus of micro-nano-composite ceramic tool materials based on microstructure model

In order to investigate the effect of microstructure parameters on the elastic modulus, based on the microstructure model represented by Voronoi tessellation, the reasonable macro-micro connection and boundary conditions were proved through the Hill’s lemma, and the uniaxial tensile process of composite ceramic tool materials was simulated. The influences of grain size, second phase volume fraction and nanoparticle volume fraction on elastic properties were studied through numerical simulation, and the elastic modulus of composite ceramic tool materials was predicted. The results showed the elastic modulus of Al2O3-based ceramic tool materials could be increased effectively with the contents of the second phase TiB2 and nano-particle TiC being 20% and 10%, respectively. The numerical simulation results were in good agreement with the experimental results.

Effect of FeTi-FeB inoculation on the shape of carbide reinforcements in hypoeutectic high chromium white cast iron

Abstract FeTi-FeB was added to molten high chromium white cast iron in amounts of 0.5–2.5 wt% at 50 °C above the melting temperature. The samples were produced in four groups. The first group samples were investigated as cast, the second group homogenized at 1000 °C for 1 h, and the other two groups were also homogenized at 1000 °C but for 3 and 6 h, respectively. To study the effect of FeB and FeTi on the microstructure, the samples were characterized by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and hardness tests. Wear tests were performed using a pin-on disc. A homogeneously dispersed carbide microstructure was produced by the homogenization heat treatment method. The addition of FeTi-FeB inoculants to high Cr white cast iron played an important role in the distribution of hard carbides. The chemical rate and the carbide volume varied on account of the added hard inoculant particles. TiB2, Cr3C2, M7C3, M23C6, and γ-FeCr phases formed on the surfaces. The hardness and wear resistance were improved considerably due to FeTi-B inoculation.

Microstructure and properties of bilayered B4C-based ceramics

Bilayered B4C-based ceramics were obtained by hot-pressing. Microstructure, mechanical and ballistic properties of the bilayered ceramics were investigated. One layer was obtained upon addition of Ti and C to the hard B4C matrix, the newly formed TiB2 phase uniformly distributed in the matrix. The other layer included variable amounts of Ti3SiC2, equal to 10, 20, 30, 40 wt%, and the B4C-SiC matrix in a fixed weight ratio of 7:3. The amount of TiB2 and SiC phases, deriving from Ti3SiC2 decomposition upon sintering, increased with increasing the Ti3SiC2 content. The flexural strength and fracture toughness of bilayered ceramics both increased with increasing the Ti3SiC2 content from 10 to 40 wt%. Ballistic testing showed that the B4C-based ceramic target containing 30 wt% Ti3SiC2 broken into pieces upon being impacted by a 12.7 mm armor-piercing incendiary (API) projectile, and effectively consumed the bullet energy and protected the backing plate from serious damage.

Enhanced strength and ductility in Ti46Al4Nb1Mo alloys via boron addition

To improve the strength and ductility of TiAl alloys by second phase, Ti46Al4Nb1Mo alloys doped with different B content (0.4%, 0.8%, 1.2%, 1.6% and 2.0%, atomic percent, hereafter in at.%, referred to as TNM-xB) were prepared. Macro/microstructure evolution, mechanical properties and deformation mechanisms of the alloys were studied systematically. Results showed that the microstructure of TNM-0.4B and TNM-0.8B alloy remained columnar dendrites, and the secondary dendritic arms of columnar grains were more obvious. When the content of B is 1.2%, the columnar dendrites transformed to equiaxed grains, and the α2/γ lamellae colony size was further refined in TNM-1.6B and TNM-2.0B alloy. The morphologies and kinds of the borides were changed with increasing B content, XRD results showed that TiB phase appeared with 1.6%B content, and both TiB and TiB2 phase formed in TNM-2.0B alloy. There were straight and curved TiB phases located around grain boundaries in TNM-0.4B and TNM-0.8B alloy, and when the content of B increased to 1.2%, the curved TiB phases were reduced, while the tiny and straight TiB phases increased. With further increasing B content to 1.6% and 2.0%, the tiny and straight TiB phases were coarser. Compressive testing results showed that the mechanical properties of the TNM alloy were enhanced with increasing B content. The maximum strength and strain of TNM alloy were 2339MPa and 33.7% with 1.6% B addition. The compressive strength and strain were mainly enhanced via refinement of lamellar colony and formation of TiB, and it is found that pile-up of dislocations and deformed twins promoted by TiB are predominant in improving the mechanical properties of TNM alloys with higher strength and strain.

A theoretical and experimental investigation on the SHS synthesis of (HfTiCN)-TiB2 high-entropy composite

In this work, a fundamental possibility of obtaining a high-entropy ceramic (HfTiCN)-TiB2 composite material by the coupled self-propagating high-temperature synthesis is shown. To search for a stable fixed composition of the HfTiCN compound, the USPEX code was used with the CASTEP interface at 0K. According to the XRD analysis, the obtained SHS product is represented by HfTiCN phase (60 wt%) and TiB2 phase (40 wt%). Based on the results of XRD, elemental analysis, and the heat pattern of combustion of the Hf-Ti-C-N-B powder mixture, a probable mechanism for the formation of the (HfTiCN)-TiB2 composite material during the coupled self-propagating high-temperature synthesis was proposed.

Insights into Poisoning Mechanism of Zr by First Principle Calculation on Adhesion Work and Adsorption Energy between TiB2, Al3Ti, and Al3Zr

Al-Ti-B intermediate alloys are widely used as grain refiners in aluminum alloys owing to the presence of Al3Ti and TiB2 phases. However, the existence of Zr in aluminum alloy melts often results in coarse grain size, leading to Al-Ti-B failure called Zr poisoning. There are three kinds of poisoning mechanisms related to TiB2, Al3Ti, and a combination of TiB2 and Al3Ti for Zr. First, Zr forms ZrB2 or Ti2Zr with TiB2 in Al-Ti-B to reduce the nucleation ability. Second, Zr existing in the aluminum melt with a high melting point Al3Zr then attracts Ti to reduce the dispersion of Ti as a growth inhibitor. Third, Zr reacts with Al3Ti on TiB2 surface to form Al3Zr, thereby increasing the degree of mismatch with Al and diminishing the refiner’s ability as a nucleation substrate. To gain a better understanding of the mechanism of Zr poisoning, the first principle was used in this study to calculate the adhesion works (ZrB2//Al3Ti), (Ti2Zr//Al3Ti), (Al3Zr//Al3Ti), (Al3Ti//Al), (TiB2//Al3Zr), and (Al3Zr//Al), as well as the surface energy of Al3Zr and adsorption energies of Al to Al3Ti or Al3Zr. The results demonstrated that Zr poisoning originated from the second guess. Zr element exiting in aluminum melt led to the formation of an Al3Zr (001) surface. The interfacial adhesion work of Al3Zr (001)//Al3Ti (001) was not weaker than that of TiB2//Al3Ti. As a result, Al3Zr first combined with Al3Ti to significantly decline the adsorption of Al3Ti (001) on Al, losing its role as a nucleating agent and grain coarsening. Overall, to prevent failure of the grain refiner in Zr containing aluminum melt, the adhesion work interface between the generated phase of the grain refiner and Al3Zr must remain lower to avoid the combination of the generated phase of grain refiner with Al3Zr. In sum, these findings look promising for evaluating future effects of grain refinement in Zr containing aluminum melt.

Effects of configuration parameters on the deformation and fracture behaviors of TiB2/Cu composites with network structure: A numerical approach using an enhanced finite element model

In order to reflect the real network composites with a hard phase TiB2 surrounded by a soft phase Cu, a developed large crystal-like cell model which closer to the real cell structure is proposed in this paper. Micro-geometric features of network TiB2/Cu composites are extracted based on the actual SEM, and a stochastic synthesis algorithm is adopted to reconstruct network structure. Based on MATLAB, a 3D network model of TiB2/Cu composites is established through Voronoi algorithm. By using finite element method, the effects of configuration parameters including TiB2 particle wall thicknesses, matrix phase sizes and matrix phase morphology on the deformation and fracture behaviors in network TiB2/Cu composites are investigated, and the mechanical properties of the composites are predicted. Three failure modes including brittle fracture of particle wall, ductile damage of matrix and traction-separation law of interface are introduced in the proposed models. The experimental stress–strain curves were implemented to verify the simulation results. The results show that the trend is in good agreement and the simulation results are stable and reliable. The comprehensive mechanical properties of network composites are assessed by yield strength, elastic modulus, elongation and tensile strength. The equivalent stress and stress concentration factor of the particle wall, brittle fracture process of network, interfacial debonding, crack damage and equivalent plastic strain of matrix are quantitatively presented. It is illustrated that the bearing capacity of network TiB2/Cu composites is determined by Cu matrix, TiB2 particle wall and interface. A macro and micro structure-properties relationship of network configuration composites is established in this paper. This work provided reference and guidance for the configuration design of the network composites in the experiment.

Effect of titanium content on the microstructure and wear behavior of Fe(13-x)TixB7 (x=0-5) hardfacing alloy

In this study, the effects of titanium addition on microstructure, hardness, and wear rate of Fe(13-x)TixB7 (x = 0, 1, 2, 3 and 5) based hard surface alloy layers formed by gas tungsten arc (GTA) welding method were investigated. As a result of the microstructure studies and phase analysis, it was determined that the structures of the coating layers consisted of ?-Fe, ?Fe+Fe2B eutectic, ?-Fe+Fe2Ti eutectic and hard TiB2 phases. In the hard surface alloy layer, as the amount of titanium was increased, the TiB2 phase density formed in the system increased and it was observed that rod-like and long sharpedged phases formed from the equiaxed structure. As a result of wear tests performed at different loads, it was determined that the addition of titanium reduces the wear rates in the coating layers. In addition, scanning electron microscopy (SEM) images of the worn surfaces showed that the wear mechanisms were adhesive and oxidative.

Модифицирование наноразмерными частицами нитрида кремния материалов на основе системы Ti – B – Fe, полученных методом СВС-экструзии

Compact ceramic SHS-electrode materials based on titanium diboride modified with silicon nitride nanoparticles have been obtained by SHS-extrusion. The phase composition, structure, and physicomechanical properties of the obtained materials have been studied. The results of scanning electron microscopy showed that, in the modified samples, grain refinement of the main phase of titanium diboride is observed, as well as a change in the phase composition of the material. With the introduction of 5 wt. % nanosized particles of silicon nitride, in addition to the main wear-resistant phase TiB2, the formation of phases is observed: TiN, Fe2B and TiSi2 located in the FeTi intermetallic matrix. The average grain sizes of TiB2 and TiN are 0.5 – 2 mm and 2 mm, respectively. With the addition of 10 wt. % Si3N4, the structure of the material consists of TiB2 and TiN phases uniformly distributed in the FeTi intermetallic matrix, and a small amount of Si and B solid solutions. The TiB2 grain size does not exceed 0.5 – 1 mm, and the TiN phase has an average grain size about 0.5 – 1.5 mm. It is shown that the obtained modified ceramic SHS-electrode materials have higher microhardness and hardness compared to the material without Si3N4 additives.

Mechanical properties of casting titanium alloy matrix composites reinforced by WC and TiB2 ceramic particulates

Casting Titanium alloys with Wc and TiB2 additives have their mechanical characteristics examined in this work. The mechanical properties of aged titanium alloys are very impressive. UTS reach 406 MPa and YS of 253 MPa and an El of 7.4 percent. Pinned primary Wc and TiB2 phases reduced fineness by more than half, while enhancing assorted nucleation on Wc and TiB2 initial phases boosted nucleation and growth resistance. Following the heat treatment, foundational designed with the intent emerged from the substrate. There are no more stages in the shell. Those alloys containing Wc, on the other hand, have cores composed of Wc and TiB2. From 0.1 wt% to 0.2 wt% of Wc and TiB2 content, core radius rises, but shell width does not appear to change, and particle density does not appear to be altered. In time, composite particles became coarser, but their core dimensions stayed nearly same. As predicted, the exponent (n-1) is less than the expected value of 0.33, Perhaps this is because of the low temperature, which prevents a developed a semi state from emerging. The kinetics are consistent with the KV model's predictions.

Investigation on Inorganic Salts K2TiF6 and KBF4 to Develop Nanoparticles Based TiB2 Reinforcement Aluminium Composites.

In the current research, AA6082 aluminium alloy matrix composites (AAMCs) incorporated with various weight fractions of titanium diboride (0, 3, 6, and 9 wt%) were prepared via an in situ casting technique. The exothermic reaction between inorganic powders like dipotassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4) in molten Al metal contributes to the development of titanium diboride content. The manufactured AA6082-TiB2 AAMCs were evaluated using a scanning electron microscope (SEM) and X-ray diffraction (XRD). The mechanical properties and wear rate (WR) of the AAMCs were investigated. XRD guarantees the creation of TiB2 phases and proves the nonappearance of reaction products in the AMCs. SEM studies depict the even dispersion of TiB2 in the matrix alloy. The mechanical and tribological properties (MTP) of the AAMCs showed improvement by the dispersion of TiB2 particles. The WR decreases steadily with TiB2 and the least WR is seen at nine weight concentrations of TiB2/AA6082 AAMCs. Fabricated composites revealed 47.9% higher flexural strength and 14.2% superior compression strength than the base AA6082 alloy.

Испытание коррозионной стойкости порошков корунда, нитрида титана и сплава эвтектического состава TiB2/TiN в среде сверхкритического водного флюида

The article presents the results of experimental studying of corrosion resistance of corundum, titanium nitride and TiB2/TiNi powder samples in supercritical aqueous fluid (SAF). The tests were proceeded in autoclave (temperature of 400 °C, steam pressure of 100 MPa) during 100 hours. As a result, it was found that Al2O3 (corundum) and TiN are resistant materials, whereas the TiB2 phase of eutectic alloy dissolves in an aqueous SAF medium. Deep corrosion index value is considered.

In-situ TiB2 and Fe2Ti intermetallic assisted hard coatings by Fe-Ti-B based hardfacing electrodes

The aim of this study was to form Fe2Ti and TiB2 phases on the steel surface in-situ using ferroalloy starting materials and to investigate the changes in the surface properties such as microstructural, hardness, wear and corrosion behavior. To this end, Fe(18−X)TiXB2 (x = 3–5) based hardfacing electrodes were produced and coated on AISI 1010 steel substrate using electric arc welding method. The development of the substrate-coating interface, solidification behavior and microstructural conditions of the samples were examined using a variety of characterization methods. In the coating microstructures, intermetallic phases such as TiB2 and Fe2Ti, α-Fe + Fe2Ti eutectic structure and trace amounts of non-equilibrium phases were detected. It has been understood that these phases formed in the microstructure have important effects on the hardness, wear and corrosion resistance of the coating. In the hardness test performed by nanoindentation method, very high hardnesses such as 3254 (± 26) HV in TiB2 phase and 1130.1 (± 13) HV in Fe2Ti phase were measured. As a result of the ball on disc reciprocal wear test performed against Al2O3 ball at different loads, it has been observed that titanium has an effect on the friction coefficient, and the wear resistance increases with the increasing amount of titanium in the electrode cover composition. In addition, according to the potentiodynamic polarization test results carried out in 3.5% NaCl solution, it has been determined that the corrosion potential increased with increasing titanium in the electrode cover composition, there was no linear change detected in the current density.

Effect of spark plasma sintering and reinforcements on the formation of ultra-fine and nanograins in AA2024-TiB2-Y hybrid composites

This study reports the influence of sintering mechanism and reinforcement materials on the formation of ultra-fine and nanograins in Al-TiB2-Y nanohybrid composites. The mechanical properties of the composites and their corresponding micro and nanostructures are correlated. The experimental and characterization results revealed that despite the addition of TiB2, the hard and brittle Al3Ti phase formation in the composites was suppressed and hence, their ductility was retained. It was found that yttrium content of 0.3 ​wt% was the optimum amount which created advantageous spark plasma sintering conditions, and the addition of 0.3 ​wt% promoted the formation of bi-modal size grains (ultra-fine and nano) along with micro grains, Ω and other nano precipitates, resulting in a significant enhancement in the composite properties. The formation of ultra-fine and nanograins may be attributed to the combined effect of melting and rapid solidification at necking zones due to Joule's heating and thermo-mechanical fatigue. Among all the sintered composites, the highest hardness (137 HV), ultimate tensile strength (UTS) (496 ​MPa), yield strength (YS) (438 ​MPa) with 15.7% elongation were obtained in the sintered sample reinforced with 1.0 ​wt% TiB2 and 0.3 ​wt% yttrium.

Application of the plasma surface sintering conditions in the synthesis of ReBx–Ti targets employed for hard films deposition in magnetron sputtering technique

Preparation of a ternary ReBx–Ti compound within a single magnetron target, forming a plasma surface sintering (PSS) conditions, were investigated. An ionized‑neon pressure of 40 Pa induced sintering power pulses (Ei) with energies of up to 3.1 kJ, which resulted in a low-porosity rhenium boride (3.2%) structure within a solid titanium matrix (ReBx–Ti). The prepared targets showed promising resistance to high temperatures (5.45 mm2/s of thermal diffusivity), after the PSS process at a temperature above 2100 °C. These as-surface-sintered magnetron targets were further used in gas injection magnetron sputtering to obtain Re–B–Ti films characterized by an enhanced deposition rate (120 nm/min). Quantitative analysis of these films revealed that the B/Re ratio was in deficit in comparison to the stoichiometry of as-prepared cathode materials. A multiple-chemical-bond state showed the occurrence of ReB, TiB, BB, TiTi, TiO, and BO phases, of which TiB2 and ReB2 were dominant, forming therefore a glass-like structure. All gathered data indicated a maximum Vickers microhardness value (36.4 GPa), emphasizing the valuable mechanical response of the deposited Re–B–Ti films, as well as the retaining of their good self-passivation effect, attributed by the oxide phases.

Kinetic study of boron diffusion in a γ-TiAl intermetallic alloy using the pack-boronising method

ABSTRACT Boronising is a thermochemical treatment which enhances the resistivity of metals used as component in applications dominated by wear and corrosion. In this study, boronising was performed on a gamma-TiAl intermetallic alloy with the pack cementation method. The experiments took place at temperatures 1173–1323 K for 8–14 h and a compact hard boride layer was formed. Its thickness varied between 6 and 25 μm. An 80 μm wide boron diffusion zone with elevated hardness was detected via micro-hardness measurements. The measured thickness values were applied to a mathematical model based on Fick’s second law of diffusion to extract the kinetic parameters of the process. Additionally, the presence of the ΤiΒ2 and the total absence of the TiB phase were confirmed via XRD measurements. The hardness of the coating and the substrate was evaluated using Vickers micro-hardness tester (above 1100 HV at the coating layer).

Structural characteristics and high-temperature tribological behaviors of laser cladded NiCoCrAlY–B4C composite coatings on Ti6Al4V alloy

In order to improve the hardness and tribological performance of Ti6Al4V alloy, NiCoCrAlY–B4C composite coatings with B4C of 5%, 10% and 15% (mass fraction) were fabricated on its surface by laser cladding (LC). The morphologies, chemical compositions and phases of obtained coatings were analyzed using scanning electronic microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD), respectively. The effects of B4C mass fraction on the coefficient of friction (COF) and wear rate of NiCoCrAlY–B4C coatings were investigated using a ball-on-disc wear tester. The results show that the NiCoCrAlY–B4C coatings with different B4C mass fractions are mainly composed of NiTi, NiTi2, α-Ti, CoO, AlB2, TiC, TiB and TiB2 phases. The COFs and wear rates of NiCoCrAlY–B4C coatings decrease with the increase of B4C content, which are contributed to the improvement of coating hardness by the B4C addition. The wear mechanisms of NiCoCrAlY–B4C coatings are changed from adhesive wear and oxidation wear to fatigue wear with the increase of B4C content.

Influence of W Addition on Microstructure and Resistance to Brittle Cracking of TiB2 Coatings Deposited by DCMS.

The aim of this work was to determine the influence of the tungsten addition to TiB2 coatings on their microstructure and brittle cracking resistance. Four coatings of different compositions (0, 7, 15, and 20 at.% of W) were deposited by magnetron sputtering from TiB2 and W targets. The coatings were investigated by the following methods: X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). All coatings had a homogeneous columnar structure with decreasing column width as the tungsten content increased. XRD and XPS analysis showed the presence of TiB2 and nonstoichiometric TiBx phases with an excess or deficiency of boron depending on composition. The crystalline size decreased from 27 nm to 10 nm with increasing W content. The brittle cracking resistance improved with increasing content of TiBx phase with deficiency of B and decreasing crystalline size.

Processing and performance assessment of particulate TiB2 reinforced aluminum MMC developed via a novel hybrid ultrasonic casting system

ABSTRACT The production of aluminum metal matrix composites (AMMCs) has been a great challenge for commercial sectors and the research fraternity. Over the past few decades, many modifications and hybrid techniques have been designed and developed by the researchers to address the manufacturing issues and reduce the production cost in developing AMMCs. In this regard, there is a need to address fundamental issues such as wettability and uniform distribution of particles across the matrix. Due to the poor mixing of particles, the materials’ hardness, strength, and wear properties are affected. In the present research, aluminum-titanium diboride metal matrix composite (Al-TiB2 MMC) has been synthesized by developing a novel hybrid liquid processing technique. The performance efficacy of the novel hybrid experiment setup has been determined through the computational fluid dynamics (CFD) approach. Metallography has been done to demonstrate the uniformity of TiB2 phase in aluminum. Mechanical and wear behavior of the Al-TiB2 MMC have been subsequently assessed and compared with conventional processing technique. The results obtained in the current study are promising and demonstrate the potential benefits of the novel hybrid liquid processing system from an industrial standpoint.

Microstructure and Abrasion Resistance of Laser Cladding CoCrFeNiTiNbB1.25 High-Entropy Alloys Coatings Treated by Aging

Laser cladding CoCrFeNiTiNbB1.25 high-entropy alloys coatings on H13 steel was fabricated. The microstructure and abrasion resistance of aged high-entropy alloys coatings at different temperature were researched. Results showed the phase was not changed in the high-entropy alloys coatings as the aging temperature elevated, the volume fraction of TiB phase was firstly increased, then reduced. The diffraction peak of fcc phase was firstly shifted to the right, and then shifted to the left. The aged high-entropy alloys coatings consisted of typical dendrite, interdendritic eutectic and dispersed intermetallic compound, and the dendrite obviously was coarsened after aging at 850 °C. Compared with non-aged high-entropy alloys coatings, the microhardness of aged high-entropy alloys coatings was firstly elevated as the aging temperature elevated, then decreased, and the mass loss was opposite. The microhardness and mass loss was decreased by 4.3% and 11.9%, respectively, for the aging at 750 °C. The abrasion mechanism of non-aged high-entropy alloys coatings was the abrasive wear, and was the abrasive wear and adhesive wear after aging.