Properties Of Titanium Matrix Composites Research Articles

Mechanical properties of titanium matrix composites fabricated via powder metallurgy method

The betterment of properties in the material can be enhanced by means of composite technology. The composite technology applied in the matrix of polymers as well as metals by reinforcement. This research comes under the classification of metal matrix composite. The titanium is widely used material. The properties of titanium proposed to reinforce by a limited weight percentage of boron carbide and graphite. The selected quantity of boron carbide 5 wt% and graphite 5 wt% used to reinforce the titanium by means of powder metallurgy technology. The prepared specimens of titanium and TMMC (reinforced with boron carbide and graphite) prepared by the processes of ball milling, compacting and sintering. The specimens included for microscopy examinations, hardness and compression investigations. The results presented and discussed in detail. The Optical Micrograph image ensures uniform distribution of reinforced particles in the matrix material.

Wear modes in open porosity titanium matrix composites with TiC addition processed by spark plasma sintering

Abstract This work focused on the influence of TiC reinforcing particles on the tribological properties of titanium matrix composites (TMCs) with open porosity, processed by spark plasma sintering (SPS). Materials composed of an equimolar mixture of Ti and TiH2 with 0, 3, 10 and 30 vol.% of TiC were sintered at 850 °C. Nanoindentation and wear tests were carried out to assess the nanohardness and the wear resistance in a tribometer with a reciprocating sliding ball-on-flat configuration. Results showed a nanohardness increment from 5 to 14 GPa with increasing TiC content. The coefficient of friction (CoF) showed a minimum of 0.2 for 10% TiC grade, which also showed the lowest wear rate. For the low TiC content sample, adhesive wear with severe plastic deformation was identified. Meanwhile, medium content TiC sample showed a mechanical mixed layer (MML), whereas high TiC content composite showed abrasive as the main wear mechanism. In conclusion, the wear mechanisms, CoFs and wear volume changed with TiC content.

Microstructure evolution and mechanical properties of titanium matrix composites and Ni-based superalloy joints with Cu interlayer

This study investigated the joining of TiBw/Ti6Al4V composites and Inconel 718 alloy with Cu interlayer using gas tungsten arc welding (GTAW) equipment in order to modify the joints strength. Microstructure analysis indicated that Ti-Cu intermetallic compounds (IMCs) and a small number of Ti-Ni-Cu compounds were generated in the reaction layer with low heat input. While the main products changed into Ti-Ni-Cu compounds, also combined with Ti-Ni compounds and a few ternary compounds with the increase of heat input. Accordingly, the shear strength of dissimilar joints firstly increased and then decreased with the increase of welding current or the decrease of welding speed. The maximum shear strength (370 MPa) was obtained with the current of 100 A and the speed of 110 mm min−1. Moreover, the hardness of reaction layer was much higher than that of parent materials due to the formation of IMCs, and medium heat input can reduce the hardness mismatch in joints.

Ambient-Temperature and High-Temperature Tensile Properties of Investment Casted Titanium Matrix Composites with B<sub>4</sub>C Additions

Titanium matrix composites (TMCs) were prepared by investment casting in a consumable arc skull casting furnace. The effects of B4C additions on ambient-temperature and high-temperature tensile properties of TMCs were investigated. It has been found that with the addition of B4C, the microstructure of TMCs was refined and the strength improved. The strength enhancement of the TMCs is ascribed to the combined effects of the second-phase strengthening, grain refinement strengthening and the solution strengthening. The grain refinement and solution strengthening effects play a main role in the yield strength enhancement of TMCs at ambient temperature, and the second-phase strengthening of TiB whiskers and TiC particles plays a more important role at high temperature.

Effect of ECAP numbers on microstructure and properties of titanium matrix composite

Abstract In this study, equal channel angular pressing (ECAP) of (TiB + TiC)/Ti6Al4V titanium matrix composite was successfully carried out at 800 °C, the effect of pass number on the microstructure and mechanical properties was investigated. After each pass of ECAP, the evolution of the microstructure and mechanical properties of (TiB + TiC)/Ti6Al4V composite during thermal-mechanical processing was studied, the Vickers micro-hardness measurements and tensile testing were performed at room temperature. The results showed that the size of the reinforcements and grains were both fully refined to a smaller scale, a number of more homogeneous TiB short fibers and TiC particles have been attained after four ECAP passes. The tensile strength increased with increasing ECAP numbers and saturated after four ECAP passes to a yield strength of 1200 MPa, and microhardness was also significantly improved by means of this processing technology, the ductility of titanium matrix composite after the four ECAP passes was slightly greater than the first ECAP pass.

Microstructure and Tribocorrosion Properties of Titanium Matrix Nanocomposites Manufactured by Selective Laser Sintering/Melting Method

This work presents an investigation of tribocorrosion properties of titanium matrix composites (TMCs) reinforced with non-oxide ceramic nanoparticles. The evaluated materials were manufactured by selective laser melting technique (SLM). As a matrix titanium and as a reinforcing phase TiC nanoparticles were used. For SLM process the mixtures of the powders composed of 0, 1, 5, 10, and 20 vol % of nanocrysalline titanium carbide (nc-TiC) were prepared. The influence of the reinforcements on the tribocorrosion properties of TMCs manufactured by SLM process was examined. Tribocorrosion “ball on disc” tests in Ringer's solution and under ambient dry conditions were carried out. It was shown that nanocomposite consisted of 20 vol.% of nc-TiC characterized by the best wear and tribocorrosion resistance.

G0400305 機械的特性に及ぼすTiB強化Ti-6Al-4V合金のマトリックス粉末の粒径と形状の影響

It has been reported that the mechanical properties of titanium matrix composites depended on titanium particle shape and size. In this study, three types of Ti-6Al-4V matrix powders were used: hydride-dehydride (HDH) powders with particle sizes of <45 μm and <25 μm and gas-atomized (GA) powder with a particle diameter of 45 μm. TiB_2 powder with an average particle size of 1.81 μm was used as a reinforcement. TiB-reinforced Ti-6Al-4V alloys were prepared by SPS. Mechanical properties of composites composed of powders with different particle shape and sizes were investigated. As a result, the mechanical properties of the composites with HDH powders depended on the particle size. The TiB whiskers were uniformly distributed in the composites with smaller Ti particle. In the composites with HDH or GA of particle size of 45 μm, their mechanical properties depended on the particle size. The tensile strength and Vickers microhardness of the composite with HDH powder were higher than those of the composite with GA powder. On the other hand, the tensile strengths of the GA composites with the GA powder exhibited higher values at a high volume fraction of TiB.

A research on the creep properties of titanium matrix composites rolled with different deformation degrees

(TiB+La2O3)/Ti composites were in situ synthesized and deformed with different deformation degrees. The influence of TiB whisker orientation and grain refinement on the creep properties of titanium matrix composites (TMCs) are discussed. The creep test reveals that the steady state creep rate of TMCs first decreases and then increases with the increase of deformation degree, which can be attributed to competing effects: TiB whisker rotating to the rolling direction, α plate grain boundary hindering and pinning dislocations can all decrease the creep rate, however, dislocation movement on the α plate grain boundary and dislocation emitting from the α plate grain boundary can both increase the creep rate.

Microstructure and Mechanical Properties of Titanium Matrix Composite Reinforced by Functionalized MultiWalled Carbon Nanotube

In this study, titanium matrix composites (TMCs) reinforced by functionalized multiwalled carbon nanotubes (MWCNTs) , prepared via powder metallurgy (PM) route. The powder mixture was pressed under 310 MPa (cold press), then sintered in vacuum furnace for 2h at 1300 °C . The Optimum mixing time under Ar atmosphere was 2h at mixing speed of 250 rpm. The microstructure of solid-state sintered composite was investigated by scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of TMC were significantly improved by addition of functionalized MWCNTs compared to the pure titanium sample, due to uniform distribution of Un-bundled MWCNTs. in during mechanical alloying process, mixture powder reached ultrafine size.

Hot compression characteristics of TiBw/Ti6Al4V composites with novel network microstructure using processing maps

As a success to improve mechanical properties of titanium matrix composites (TMCs), in situ TiB whiskers reinforced Ti6Al4V (TiBw/Ti64) composites were fabricated by tailoring a novel network microstructure. The hot compressive deformation of the composites was preformed in the temperature range of 900–1100°C and a strain rate range of 0.001–10s−1. The processing maps of the composites are constructed using the compression data based on the dynamic material model (DMM). The optimal deformation regime and the instable deformation regime are established by the processing maps. The microstructure of compressed specimen can be divided into non-deformation region I, transition deformation region II, homogenous deformation region III and circum deformation region IV. Hot deformation corresponding with peak efficiency combined with TiBw reinforcement encourages dynamic recrystallization (DRX) of α phase. Additionally, the instable characteristics of the network structured TiBw/Ti64 composites can be expressed as debonding, cracking, flow localization band and thin homogenous deformation region.

Producing Ti–6Al–4V/TiC composite with superior properties by adding boron and thermo-mechanical processing

In order to study the effect of boron addition on the microstructure and tensile properties of titanium matrix composites, two Ti–6Al–4V/10Vol% TiC ingots with and without boron were fabricated by VIM furnace and hot rolling. The microstructures of composites were examined using optical microscopy (OM). The X-ray diffraction (XRD) was used to identify the phases present in the composites. Addition of boron resulted in the formation of needle shaped TiB in the matrix that was followed by the refinement of grain size. Compared with Ti–6Al–4V/TiC composite, the composite containing boron content exhibited a significantly higher ductility and lower strength. It was caused by the effects of boron element on reducing TiC particle size and solubility of carbon in alpha matrix. According to the results obtained in this study, the hybrid effect of TiC and TiB plays an important role in the mechanical properties, especially ductility of titanium matrix composites (TMCs). Finally, we have produced TMCs strip with excellent ductility (9% elongation and 18% reduction area) and good strength (∼1240MPa).

Investigation on the surface layer characteristics of shot peened titanium matrix composite utilizing X-ray diffraction

The surface layer characteristics of shot peened (TiB+TiC)/Ti–6Al–4V composite are investigated using X-ray diffraction line profile analysis. The structural breadth, domain sizes, microstrain and dislocation densities of the matrices and composite are obtained. The results show that the domain sizes are refined after shot peening, and the dislocation densities are increased sharply in the near surface layer, which result from the high kinetic energy of shot balls in the process of shot peening. Comparing with the calculated results of the matrices and composite, it can be found that the microstructure variations of matrices are more severe than composite's, which is ascribed to the effect of reinforcements' resistance to the surface layers' deformation. Besides, the distributions of residual stresses and microhardness with different shot peening intensities and reinforcement volume fractions have been discussed, and the effects of reinforcements and shot peening intensities have been indicated. According to above detailed discussions, the results reveal that shot peening is an essential process of improving the surface properties of titanium matrix composite.

Influence of nano-reinforcements on the mechanical properties and microstructure of titanium matrix composites

The goal of this work is the evaluation of nanoscaled reinforcements; in particular nanodiamonds (NDs) and carbon nanotubes (CNTs) on properties of titanium matrix composites (TiMMCs). By using nano sized materials as reinforcement in TiMMCs, superior mechanical and physical properties can be expected. Additionally, titanium powder metallurgy (P/M) offers the possibility of changing the reinforcement content in the matrix within a very wide range. In this work, TiMMCs have been produced from titanium powder (Grade 4). The manufacturing of the composites was done by hot pressing, followed by the characterisation of the TiMMCs. The Archimedes density, hardness and oxygen content of the specimens in addition to the mechanical properties were compared and reported in this work. Moreover, XRD analysis and SEM observations revealed in situ formed titanium carbide (TiC) phase after hot pressing in TiMMCs reinforced with NDs and CNTs, at 900 °C and 1100 °C respectively. The strengthening effect of NDs was more significant since its distribution was more homogeneous in the matrix.

Microstructural and Mechanical Properties of Titanium Matrix Composites Reinforced with Nano Carbon Materials via Powder Metallurgy Process

Powder metallurgy (P/M) titanium matrix composite (TMC) reinforced with multi-wall carbon nanotube (MWCNT) was prepared by spark plasma sintering (SPS) and hot extrusion process, where the powder surface was coated by un-bundled CNTs via wet process. The microstructure and mechanical properties of P/M pure titanium and reinforced with CNTs were evaluated. The distribution of CNTs and in-situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyser. The mechanical properties of TMC were significantly improved by adding a small amount of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of specimens were analysed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed.

Hybrid effect of TiBw and TiCp on tensile properties of in situ titanium matrix composites

In order to study the hybrid effect of in situ TiB whisker (TiBw) and TiC particle (TiCp) on the tensile properties of titanium matrix composites (TMCs), TMCs with various TiBw/TiCp volume ratios of 4:1, 1:1 and 1:4 were prepared by reactive hot pressing of blended powders of Ti, B4C, and graphite. Room tensile testing results exhibited that the composite with TiBw/TiCp volume ratio of 1:1 experienced an increase in the ultimate tensile strength of 25 and 50%, respectively, over the composite with ratio of 4:1 (based on Ti–B4C) and pure Ti. The hybrid strengthening effect still existed at elevated temperature but it was not as obvious as that of room-temperature. Meanwhile, the ductility of the composites was decreased with decreasing TiBw content. The results suggest that the hybrid effect exists both at room and at elevated temperatures and it should be taken into account to prepare TMCs with good mechanical properties.

Fabrication and tensile properties of in situ TiBw and TiCp hybrid-reinforced titanium matrix composites based on Ti–B 4C–C

To evaluate the synergistic effect of TiB whisker (TiBw) and TiC particle (TiCp) on tensile properties of titanium matrix composites (TMCs), 10 vol.% TiBw and TiCp reinforced TMCs with TiBw/TiCp volume ratios of 4:1, 2:1, 1:1, 1:2, and 1:4 were prepared by reactive hot processing of Ti–B 4C–C. The tensile strength and modulus of the TMCs were greatly improved due to the formation of TiBw and TiCp. The composite with the ratio of 1:1 possessed the best tensile properties among the composites. Fractography showed that all the composites possess a brittle cleavage fracture mode at room-temperature, and TiCp can prevent cracks from being formed more effectively than TiBw. The results show that the synergistic effect of TiBw and TiCp significantly affects the tensile properties of TMCs, and a proper volume ratio of TiBw to TiCp would provide the composite with better properties.

Mechanical and Microstructural Properties of Titanium Matrix Composites Reinforced by TiN Particles

Particulate reinforced titanium composites were produced by PM route. Different volumetric percentages of TiN reinforcements were used, 5,10,15 vol%. Samples were uniaxially pressed and vacuum sintered at different temperatures between 1200-1300°C. Density, porosity, shrinkage, mechanical properties and microstructure were studied. Elastic properties and strength resistance were analysed by flexural strength and tension tests, and after the test, fractured samples were analysed as well to obtain the correlation between the fracture, interparticular or intraparticular, and the level of reinforcement addition. Hardness and microhardness test were done to obtain a better understanding of its mechanical properties. In order to study wear resistance pinon- disc tests were conducted. In addition, the influence of temperature, the reactivity between matrix and reinforcement on microstructural development were observed by optical and electron microscopy.

Effect of C coating on the interfacial microstructure and properties of SiC fiber-reinforced Ti matrix composites

C coating of the SiC fiber critically influences the interfacial microstructure and properties of titanium matrix composites, and thus affects the overall composite properties. In this work, the interfacial microstructure and debond strength of SiC(C)/Ti–6Al–4V and SiC/Ti–6Al–4V composites was studied by comparison. The C coating prevented direct fiber–matrix interaction, and the interfacial reaction product for SiC(C)/Ti–6Al–4V composite was only TiC, comprising fine particles adjacent to the C coating and coarse particles adjacent to the matrix. At the interface of SiC/Ti–6Al–4V composite, a narrow layer of fine TiC particles was adjacent to the fiber, and a broad mixture layer of TiC and Ti 5Si 3 particles was adjacent to the matrix; the particle size increases gradually from the fiber to the matrix. C coating offered a weak interfacial bonding between the fiber and matrix, and the interfacial debond strength for SiC(C)/Ti–6Al–4V and SiC/Ti–6Al–4V composites was 118.2 ± 4.24 and 230 ± 6.28 MPa, respectively. Interfacial debonding occurred between the C coating and the reaction layer for the coated fiber composite, but between the fiber and the interface reaction layer for the naked fiber composite.

Optimisation of the Fatigue Resistance of Metal Matrix Composites

Fiber reinforced titanium matrix composites (TMCs) are attractive materials for future aerospace applications. Reinforcement of Ti alloys with SiC fibers leads to a significant increase on strength and stiffness, especially under high stress loading or at elevated temperatures. Mechanical properties of TMCs are strongly influenced by thermal residual stresses (TRS). A reduction of TRS leads to an increase in fully reversed high cycle fatigue resistance of TMCs at room temperature. Reduction of TRS can be easily obtained by prestraining during single tension loading of TMCs in the as processed condition.

Development and characterization of new coatings for improved balance of mechanical properties of titanium matrix composites

Abstract The need for improved transverse performance of titanium matrix composites (TMCs) has stimulated efforts at developing fiber–matrix coatings with a better blend of transverse and longitudinal properties. In the first part of this paper, the critical requirements for an appropriate coating are examined, based on experience gained from single-fiber and single-ply tests on TMCs. Two new coatings are then discussed: (i) the Ti-Y-Ti system, abbreviated as TYT; and (ii), the sheathed SiC system. The coatings were characterized under transverse loading using the cruciform specimen geometry, and under longitudinal tension using a single-ply dog-bone geometry. The transverse strength of the TYT system was ≈160 MPa, and needs further improvement. The fiber had poor in situ strength, and is explained based on less than expected performance of the Y layer due to oxygen pickup and columnar grain structure. The sheathed fiber offered a better blend of transverse and longitudinal properties. Under transverse loading, the sheath remained load bearing until an applied stress as high as 550 MPa, compared with only 330 MPa for SCS-6 fibers. Under longitudinal tension, while the sheath cracked at relatively low stresses, the base SiC region appeared to retain a strength that was identical to a virgin carbon-coated Trimarc fiber. The sheathed fiber appears attractive for TMC laminates, and further experimental validation is suggested.