Particle Reinforced Titanium Matrix Composites Research Articles

Dynamic Compressive Properties and Failure Mechanism of the Laser Powder Bed Fusion of Submicro-LaB6 Reinforced Ti-Based Composites.

In this study, lanthanum hexaboride (LaB6) particle-reinforced titanium matrix composites (PRTMCs, TC4/LaB6) were successfully manufactured using the laser powder bed fusion (LPBF) process. Thereafter, the effect of the mass fraction of LaB6 on the microstructure and the dynamic compressive properties was investigated. The results show that the addition of LaB6 leads to significant grain refinement. Moreover, the general trend of grain size reveals a concave bend as the fraction increases from 0.2% to 1.0%. Furthermore, the texture intensity of prior β grains and α grains was found to be weakened in the composites. It was also observed that the TC4/LaB6 have higher quasi-static and dynamic compressive strengths but lower fracture strain when compared with the as-built TC4. The sample with 0.5 wt.% LaB6 was found to have the best strength-toughness synergy among the three groups of composites due to having the smallest grain size. Furthermore, the fracture mode of TC4/LaB6 was found to change from the fracture under the combined action of brittle and ductility to the cleavage fracture. This study was able to provide a theoretical basis for an in-depth understanding of the compressive properties of additive manufacturing of PRTMCs under high-speed loading conditions.

Simulation Study of Ultrasonic Elliptical Vibration Cutting of TiC Particle-Reinforced Titanium Matrix Composites

In order to investigate the characteristics of elliptical ultrasonic vibration cutting of TiC particle-reinforced titanium matrix composites, a two-dimensional thermodynamic coupled finite element cutting model was established based on the Johnson-Cook intrinsic structure model using ABAQUS simulation software, and the changes in cutting force, cutting temperature, machined surface shape, and particle fragmentation were obtained under the traditional cutting method and ultrasonic elliptical vibration cutting method. The results show that under the same process parameters, ultrasonic elliptical vibration cutting is better than conventional cutting in terms of surface profile; the stress direction tends to be horizontal during cutting and the TiC particles are mainly removed by cutting off. The average cutting force is significantly lower than conventional cutting, with a maximum reduction of 60%. The cutting temperature is also reduced, with a reduction of approximately 17.6%.

Machinability of TiC-reinforced titanium matrix composites fabricated by additive manufacturing

Additive manufacturing (AM) of TiC particle-reinforced titanium matrix composites (TiC-TMCs) has promising applications in aircraft and aerospace, attributed to its advantages of near-net shaping for AM and the excellent mechanical properties for TiC-TMCs. However, the surface quality of AM produced parts is inferior to that of the conventionally formed parts. This study investigated the machinability for TiC-TMCs specimens prepared by AM. The microstructural characteristics of TiC after AM were analyzed. The effects of the microstructure on cutting force, machined surface morphology, chip formation, and tool wear were studied. The results showed that a varied set of AM parameters caused a different microstructure and thus different machinability of TiC-TMCs. Compared to the specimens with coarse dendritic TiC, the fine equiaxed TiC possessed better machined surface quality and lower tool wear and thus better machinability. This study is expected to further exploit the advantages of AM and promote precision manufacturing of TiC-TMCs parts.

Microstructure and mechanical properties of Ti-Ta based composites enhanced by in-situ formation of TiC particles

TiC particle reinforced titanium matrix composites show excellent mechanical properties, which are widely regarded as promising high-performance structural materials. Here, we fabricated in-situ TiC enhanced Ti Ta based composites through mechanical alloying of elemental Ti and Ta powders and subsequently followed by spark plasma sintering and hot rolling. The stearic acid was utilized as both process control agent and carbon source. Experimental results show that Ti-enriched area, Ta-enriched area and TiC particles can be observed after sintering, and TiC particles are all distributed inside Ti-enriched area. After hot rolling, Ti-enriched areas and Ta-enriched areas are elongated along the rolling direction. The tensile strength increases and the ductility decreases with increasing content of in-situ formed TiC particles. The yield strength, the ultimate tensile strength of Ti Ta composite with 8 wt% TiC reach up to 1035 MPa and 1287 MPa, respectively, with a ductility of 1.6%. The enhanced strength is due to dislocation hardening, solid solution between Ti and Ta, grain boundary hardening and TiC particulate reinforcement. Besides, the solid solution of O element and the heterogeneous structure of Ti Ta composites may also improve the strength. This method provides an efficient way to fabricate in-situ TiC particle enhanced titanium based composite with improved strength. • The Ti-Ta composites presented heterogeneous structure with Ti-enriched, Ta-enriched and diffusional regions. • TiC particles were generated through in-situ reaction between Ti matrix and stearic acid. • The strength enhanced by in-situ formed TiC particles is higher than 200 MPa. • The strengthen mechanisms were determined to simulate the strength of Ti-Ta composites.

Effect of local reinforcement particle distribution on mechanical properties of in-situ TiB/TiC1-x particle reinforced Ti-5Al-5Mo-5V-3Cr – comparison between model and experiment

In-situ TiB and TiC1-x particle-reinforced titanium matrix composites (TMCs) based on a near-β Ti-5Al-5Mo-5V-3Cr alloy (Ti-5553) reacting chemically with 4 vol.-% B4C were processed by spark plasma sintering (SPS). Different local distributions of the reinforcement particles formed within the composite were adjusted by varying the conditions during powder preparation. The measured Young’s modulus, hardness and compressive yield strength of the composites increased, as the reinforcement particles were distributed more homogeneously within the matrix. In addition, Young’s modulus and hardness were modelled considering the hybrid TiB-whisker and TiC-particle reinforcement applying the rule of hybrid mixtures (RoHM) and the Fu-method, respectively. The compressive yield strength was modelled in ac-cordance with the summation of the particular effective strengthening mechanisms and the Clyne-method. Measured values of the Young’s modulus and the hardness were overestimated by the modelling as the clustering of the reinforcement particles increased. The compressive yield strength of the composites is modelled appropriately using the Clyne-method. However, pronounced agglomeration of the reinforcing particles within the matrix resulted in an overesti-mation of the measured values.

Hot Deformation Behaviors in Ti-6Al-4V/(TiB + TiC) Composites

Thermal compression testing was investigated using the Gleeble 3800 thermal simulator, and thermal deformation behavior of particle-reinforced titanium matrix composites (TMCs) was studied under deformation temperatures of 750–900 °C, strain rates of 0.001–1 s−1, and experimental deformation of 60%. According to obtained flow stress curves, the hot deformation characteristics were analyzed. Based on the Arrhenius hyperbolic sinusoidal model, the constitutive equation at high temperature was established. Based on the theory of dynamic material models, a hot processing map of TMCs at high temperature was established, and the peak region of power dissipation rate and the instability region in the hot processing map were both determined. At the same time, the corresponding microstructures in the peak power dissipation rate and rheological instability regions were observed. The results showed that flow stress decreased with increasing deformation temperature and increased with increasing strain rate. The thermal deformation activation energy of titanium matrix composites was 301.8 kJ/mol. The Ti-6Al-4V/(TiB + TiC) composites possessed only one instability zone under high-temperature compression at a strain of 0.5, with corresponding temperatures at 750–840 °C and strain rates at 0.1–1 s−1. The optimal thermal deformation parameters included corresponding temperatures of 830–880 °C and strain rates of 0.001–0.05 s−1. The microstructures corresponding to optimal hot working parameters in processing maps were more homogeneous than the microstructures in the instability zone, including the distribution uniformity of reinforcement and the degree of dynamic recrystallization, and no instability phenomena including abnormal grain growth, microcracks or intensive fracture of reinforcements were found, indicating that the hot processing map had a positive guiding effect on the option of desirable material thermal-working parameters.

Development of constitutive equations for hot working of titanium matrix composites

This research is devoted to modelling the viscoplastic deformation behaviour and microstructure evolution of particle reinforced titanium matrix composites (TMCs) at hot working conditions. A series of Gleeble hot compression tests were conducted to obtain the stress-strain curves. According to the dominant mechanisms of TMCs during deformation, a set of mechanism-based constitutive equations was developed and fitted based on the experiment data. Lamellar alpha globularisation, dynamic recrystallization and damage were considered and incorporated into the constitutive equations to describe the viscoplastic flow behaviour.

Cyclic plasticity and creep-cyclic plasticity behaviours of the SiC/Ti-6242 particulate reinforced titanium matrix composites under thermo-mechanical loadings

The purpose of this work is to investigate the cyclic plasticity and creep-cyclic plasticity behaviours of particle reinforced titanium matrix composites (PRTMCs) SiC/Ti-6242, aimed to be used in high temperature applications. The investigation has been conducted upon microstructures that have been taken from a previous study where low-fidelity model-based optimization (LFMBO) has been used to maximise the elastic behaviour of particle reinforced aluminium matrix composites. The effect of the particle spatial distribution, particle fraction volume and number of particles on the shakedown limit, limit load and creep-cyclic plasticity have been explored by direct numerical techniques based on the Linear Matching Method (LMM) framework. The micromechanical approach to modelling and fifteen multi-particle unit cells have been investigated. Under cyclic loading conditions, the structural response of PRTMCs is not trivial and becomes even more significant when high temperature is involved. Hence, the factors that affect the creep and cyclic plasticity of PRTMCs are analysed and discussed, including effects of the applied load level, dwell period and temperature on the composites’ performance. The applicability and accuracy of the proposed direct method has also been verified by the step-by-step analysis.

Microstructure and Mechanical Properties of In Situ TiB/TiC Particle-Reinforced Ti-5Al-5Mo-5V-3Cr Composites Synthesized by Spark Plasma Sintering

In situ TiB and TiC particle-reinforced titanium matrix composites (TMCs) based on a near-β Ti-5Al-5Mo-5V-3Cr alloy (Ti-5553) reacting chemically with B4C were processed by spark plasma sintering (SPS). The influence of powder milling parameters (low-energy mixing or high-energy milling) on the chemical reaction behavior between the matrix and the B4C particles during sintering was investigated. Taking the microstructure into account, characterization of the particle strengthening effect was carried out under compressive loading conditions. High-energy milling resulted in a significantly higher degree of B4C conversion during sintering. This was attributed to plastic deformation of the initial matrix powder and more homogeneous distribution of the B4C particles accompanied by a significant reduction in cluster formation. In comparison to the unreinforced Ti-5553 matrix, the hardness, stiffness, and compressive strength of the TMCs were successfully increased due to particle reinforcement. The powder milling treatment improved these properties further—a phenomenon directly associated with the higher degree of B4C conversion. Instead of the expected formation of stoichiometric TiC, the formation of nonstoichiometric TiC1−x with x ≈ 0.5 was observed. Molybdenum, vanadium, and chromium formed a solid solution in TiB and TiC1−x. Additionally, the titanium content in the matrix particles was markedly reduced, while the aluminum content roughly doubled.

A Meso-Mechanical Constitutive Model of Particle-Reinforced Titanium Matrix Composites at High Temperatures

The elastoplastic properties of TiC particle-reinforced titanium matrix composites (TiC/TMCs) at high temperatures were examined by quasi-static tensile experiments. The specimens were stretched at 300 °C, 560 °C, and 650 °C, respectively at a strain rate of 0.001/s. scanning electron microscope (SEM) observation was carried out to reveal the microstructure of each specimen tested at different temperatures. The mechanical behavior of TiC/TMCs was analyzed by considering interfacial debonding afterwards. Based on Eshelby’s equivalent inclusion theory and Mori-Tanaka’s concept of average stress in the matrix, the stress or strain of the matrix, the particles, and the effective stiffness tensor of the composite were derived under prescribed traction boundary conditions at high temperatures. The plastic strains due to the thermal mismatch between the matrix and the reinforced particles were considered as eigenstrains. The interfacial debonding was calculated by the tensile strength of the particles and debonding probability was described by Weibull distribution. Finally, a meso-mechanical constitutive model was presented to explore the high-temperature elastoplastic properties of the spherical particle-reinforced titanium matrix composites by using a secant modulus method for the interfacial debonding.

Effect of Zr, Mo and TiC on microstructure and high-temperature tensile strength of cast titanium matrix composites

In this paper, five types of TiC particle reinforced titanium matrix composites (TiC-PTMCs) were fabricated by casting route in order to investigate the influence of Zr, Mo and TiC on microstructures and tensile strengths of TiC-PTMCs. The increase of Zr content promoted the precipitation of eutectic TiC and refined primary TiC, while increasing Mo content led to the refinement of α lath. The composites with high Zr and Mo contents and low TiC content showed superiority in ultimate tensile strength (UTS) below 650°C, whereas above 700°C, high UTS was obtained in the composites with high TiC content and low Mo content. Below 650°C, solid solution strengthening and fine grain strengthening of matrix make the largest contribution to the improvement of UTS. However, above 700°C, solid-solution strengthening of Zr and the load bearing effect of TiC play a dominant role in the enhancement of UTS. Accordingly, effective routes for improving UTSs of TiC-PTMCs in different temperature ranges are different.

Fabrication and characterisation of Titanium Matrix Composites obtained using a combination of Self propagating High temperature Synthesis and Spark Plasma Sintering

This work presents a novel processing method for the fabrication of particle reinforced Titanium Matrix Composites (TMCs). TMCs are a promising alternative to improve the mechanical properties of titanium alloys. In the processing method, the reinforcement (TiC–Ti) was obtained by Self-propagating High-temperature Synthesis (SHS). The composition of the reinforcement was Ti1.3C. An excess of titanium compared to the equiatomic TiC was introduced in the reaction in order to control the size of the reinforcement and to improve the compatibility between reinforcement and matrix. This reinforcement was mixed with Ti–6Al–4V powder and the final consolidation of the TMC was performed by Spark Plasma Sintering (SPS). The microstructure and mechanical characterisation of the TMCs are presented. Comparing tensile properties with conventional Ti–6Al–4V alloys, the materials developed in this work present higher young modulus and tensile strength. In addition, in order to study the possible scale up of SPS process for the production of TMCs, the manufacturing of large samples was studied.

Finite element analysis on hot deformation behavior of TiC-particle-reinforced titanium matrix composite

Purpose – The purpose of this paper is to investigate tensile properties of TiC particle-reinforced titanium matrix composites (PRTMC) using the elasto-plastic finite element (FE) programs and the homogenization method and the fixed point iteration method. Design/methodology/approach – Two quasi-static and dynamic transient programs of elasto-plastic FE were coded by using FORTRAN. Based on the FE programs, the FE model of the TiC PRTMC with typical microstructures was established by using the fixed point iteration method and the homogenization theory. The hot deformation behavior of TiC PRTMC under different temperatures were analyzed by using the above model and programs. Findings – Calculation results are presented to investigate the influence of different temperatures on the hot deformation behavior of TiC PRTMC. Based on the experimental data, a good agreement was obtained between the numerical predictions and the experimental results, and the feasibility of this method was verified. Originality/value – The work is original and findings are new, which demonstrates this FE frame combined with the homogenization method and the fixed point iteration method can be used to investigate the tensile behavior of particle-reinforced metal matrix composites.

A Meso-Mechanical Constitutive Model of Particle Reinforced Titanium Matrix Composites Subjected to Impact Loading

A meso-mechanical constitutive model of TiC particle reinforced titanium matrix composites (TiC/TMCs) under impact loading is established to investigate the mechanical behavior of TiC/TMCs. Based on Eshelbys equivalent inclusion theory and Mori-Tanakas concept of average stress in the matrix, the compliance tensor is formulated. By adding nucleation and growth crack models, the influences of micro-cracks on compliance tensor and damage evolution are examined. Finally, a one-dimensional dynamic constitutive model subjected to impact loading is presented to explore the mechanical behavior of TiC/TMCs.

Fabrication and mechanical properties of in situ TiC/Ti metal matrix composites

In situ TiC particle reinforced titanium matrix composites (TMCs) were successfully fabricated by reactive sintering of Ti+Mo2C and Ti+VC compacts. The results of the tensile tests at ambient and elevated temperatures show that the strength of the composites increases with increasing additive content (Mo2C and VC), and decreases with increasing temperatures. Comparing the two types of TMCs, the Ti+VC composites have a lower strength than the Ti+Mo2C composites, but can more effectively retain the strength to elevated temperatures. Microstructural analyses show that the main strengthening mechanisms of the TMCs are solid solution, grain refinement and particulate strengthening. Different dominant strengthening mechanisms in different composites are responsible for the variations of the mechanical properties. At elevated temperatures, the volume fraction of TiC particles is the main factor for increasing the strength.

Oxidation behavior of in situ synthesized (TiB + TiC)/Ti–Al composites

In the present study, oxidation behaviors of TiB and TiC particle reinforced titanium matrix composites (TMCs) were performed in air at 823–923 K. The oxidation kinetics follows approximately a parabolic rate law. The oxidation rates decrease gradually as the oxidation proceeds. The oxide scales formed on TMCs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), X photoelectron spectrometry (XPS), and transmission electron microscopy (TEM). The oxygen coefficients in oxide and solid solution were estimated from microhardness measurements. The oxide scale formed was composed of an outer rutile layer, an intermediate alumina-rich layer, and a rutile-rich layer. The oxide scales formed exhibited excellent spallation resistance under all testing conditions. No scale cracking or spallation could be observed, implying that growth and thermal stresses generated during heating and cooling periods had been effectively released. The mechanisms of the improvement on spallation resistance are discussed based on microstructure studies.

Oxidation of in situ synthesized TiC particle-reinforced titanium matrix composites

The oxidation behavior of TiC particle reinforced titanium matrix composites (TMCs) was studied in a temperature range 550–650 °C in atmosphere. The in situ oxidation observation at the very initial stage was investigated by high-temperature optical microscopy in air. The oxide layer of long-term oxidation behavior was examined by scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectroscopy unit (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The oxidation kinetics follows a parabolic rate law. The oxidation rate decreases gradually as the oxidation proceeds. The oxidation of the composite took place firstly on Ti because of the higher reactivity of Ti and O 2 than that of TiC and O 2. However, the TiC reinforcement can decrease the overall oxidation rate at 550, 600, and 650 °C. It is attributed to the formation of thin and dense oxidation, the enough strong interface cohesion between reinforcements and the titanium matrix alloy.