Ti-based Metal Matrix Composites Research Articles

Eutectic composition titanium metal matrix composites for laser powder bed fusion via surface remelt analyses

Ti-based metal matrix composites (MMCs) represent a material class with highly desired performance for the aerospace industry, but implementation has been hindered by poor processability. It is now being realised that MMCs can be formed in situ through the exploitation of rapid cooling rates of laser powder bed fusion, and targeting invariant reaction compositions to minimise the propensity for solidification cracking. We perform laser line scans and surface remelts of arc-melted Ti–0.38C, Ti–1.67B, Ti–8.5Si and Ti–32.5Fe wt-% eutectic compositions to assess potential material amenability to the laser powder bed fusion (LPBF) process at low cost as well as determining the nanostructure and hardness properties. The results indicate that MMCs are amenable to LPBF and may outperform conventional alloys.

A review on Ti-based metal matrix composite coatings

Lightweight high-strength Ti-based metal matrix composites (Ti-based MMCs) have a multitude of application applications, e.g., biomedical engineering, aerospace, and automotive, due to their good sustainability, high specific strength/stiffness, high elevated temperature strength, high wear, and corrosion resistance. Although there are metal matrix composite coatings comprised of polymers, composite, and ceramics materials, the paper primarily focuses on titanium-based composite coatings. This review also discusses the different coating techniques including electrodeposition, thermal spray, plasma spray, vapor deposition, and laser cladding to achieve high hardness and roughness, wear resistance and corrosion resistance. Totally, we attempt to bring out Ti based materials scenario for its current applications.

Evolution of microstructure and mechanical properties of Ti-based metal-matrix composites during hot deformation

Two Ti-based composites, viz. Ti/TiB and Ti-15Mo/TiB were produced by spark plasma sintering using a Ti-10wt.%TiB2 powder mixture at 1000°C or Ti-14.25(wt.)%Mo-5(wt.)%TiB2 powder mixture at 1400°C, respectively. Specimens of the metal-matrix composites (MMCs) were subjected to uniaxial compression in the temperature range from 500 to 1050°С to determine processing window. Processing maps for both MMCs were constructed and analyzed. Mechanical behavior and microstructure evolution of both MMCs during multiaxial forging (MAF) at 700°C and at a strain rate 10-3 s-1 were studied. The flow stress for the Ti-15Mo/TiB MMC during MAF was ∼2 times higher than that for the Ti/TiB composite. Microstructure evolution during MAF of Ti/TiB MMC was associated with continuous dynamic recrystallization of the titanium matrix and shortening of TiB whiskers by a factor of ~3. The Ti-15Mo/TiB composite microstructure after did not demonstrate the development of recrystallization.

Evolution of microstructure and mechanical properties of Ti-based metal-matrix composites during high-pressure torsion

The microstructure and microhardness evolution of a Ti/TiB and Ti-15(wt.%)Mo/TiB metal-matrix composites (MMC) during high-pressure torsion (HPT) at 400 °C was studied. The composites were fabricated by spark plasma sintering of either hcp α-Ti with 10 wt.% of TiB2 or Ti with 13.5 wt.% of Mo (resulted in a bcc β-Ti matrix) and of 10 wt.% TiB2 powders mixtures at 1000 or 1200 °C, respectively. An increase in the dislocation density, a considerable decrease in the grain size in both hcp or bcc Ti matrix, and shortening of TiB whiskers were observed in the microstructures of the composites during HPT. After five revolutions, a nanostructure with a (sub) grain size of ~30 or ~55 nm was produced in Ti or Ti-15Mo matrix, respectively. The microhardness increased with strain from 452 HV in the initial state to 520 HV after 5 revolutions for Ti/TiB MMC and from 575 to 730 HV for Ti-15Mo/TiB MMC. The contributions of various hardening mechanisms to the composites were evaluated.

Al–Cr–Fe quasicrystals as novel reinforcements in Ti based composites consolidated using high pressure spark plasma sintering

Ti based metal matrix composites (MMCs) reinforced with Al–Cr–Fe quasicrystals have been prepared using high pressure spark plasma sintering (HP-SPS) with a high heating/cooling rate of 200°C/min between 550°C and 750°C and without any isothermal process. As the sintering pressure increases, the compositional variation of Al–Cr–Fe reinforcements diminishes. It is found that under a sintering pressure of 250MPa, the phases in Al–Cr–Fe powders, including two quasicrystals, decagonal Al–Cr–Fe and icosahedral Al–Cr–Fe, and two of their approximants, Al9(Cr,Fe)4 and Al8(Cr,Fe)5, can be preserved. An interfacial layer forms between Ti matrix and Al–Cr–Fe reinforcements in the sintering process. This interfacial layer consists of Al3Ti and AlTi. The incorporation of 20wt.% Al–Cr–Fe particles into Ti matrix was found to improve the microhardness to Hv 480 and reduce the wear rate by around 70%. This implies that Al–Cr–Fe is a promising reinforcement candidate for Ti.

Novel Ti based metal matrix composites reinforced with Al–Cr–Fe quasicrystals approximants

In this work, Ti/Al–Cr–Fe metal matrix composites were fabricated with Ti as matrix and Al–Cr–Fe quasicrystal approximants as reinforcements using spark plasma sintering. In all samples a Ti3Al ring forms around each Al–Cr–Fe particle as a bonding layer between Ti and Al–Cr–Fe particles. In the sample sintered with a holding time of 5 min, there are only TiAl regions present at the Ti3Al/Al–Cr–Fe interface. However, in the samples sintered with a holding time of 10, 15 or 20 min, TiAl, Ti(Al,Cr)2 and L12 regions were detected at the Ti3Al/Al–Cr–Fe interface. The addition of Al–Cr–Fe particles into the Ti matrix was found to improve the mircrohardness to 460 HV and increase the wear resistance by more than 50%.

Oxygen-diffused titanium as a candidate brake rotor material

Titanium alloys are one of several candidate materials for the next generation of truck disk brake rotors. Despite their advantages of lightweight relative to cast iron and good strength and corrosion resistance, titanium alloys are unlikely to be satisfactory brake rotor materials unless their friction and wear behavior can be significantly improved. In this study, a surface engineering process – oxygen diffusion (OD) – was applied to titanium rotors and has shown very encouraging results. The oxygen-diffused Ti–6Al–4V (OD-Ti64) was tested on a sub-scale brake tester against a flat block of commercial brake lining material and benchmarked against several other Ti-based materials, including untreated Ti–6Al–4V (Ti64), Ti-based metal matrix composites (MMCs), and a thermal spray-coated Ti alloy. With respect to friction, the OD-Ti64 outperformed all other candidate materials under the imposed test conditions with the friction coefficient remaining within a desirable range of 0.35–0.50, even under the harshest conditions when the disk surface temperature reached nearly 600 °C. In addition, the OD-Ti64 showed significantly improved wear-resistance over the untreated Ti64 and was even better than the Ti-based composite materials.

Microstructural Analysis on Ti-6Al-4V and 10 Vol.% (TiB+TiC)/Ti-6Al-4V Metal Matrix Composites

Particulate reinforced Ti based metal matrix composites (MMCs) were made by in-situ synthesis using vacuum arc re-melting process. The microstructure of the Ti-6Al-4V base alloy and 10 vol.% (TiB+TiC)/Ti-6Al-4V metal matrix composites was examined. The particulate reinforcements were analysed and identified TiB and TiC particles. The particle distribution was analysed using the quadrat method over 1620 quadrats. A homogeneous particle distribution was found to establish in the composites. The experimental distribution of the reinforcements agreed well with the theoretical Poisson distribution. A skew factor, which characterizes the degree of asymmetry of a statistical distribution, of 1.108 was determined for the particle distribution in the material.

A theoretical study of fatigue behaviour in unidirectional Ti-based metal matrix composites

The Fatigue Damage Map (FDM) has been used to define the different damage mechanisms operating during fatigue loading of fibre reinforced metal matrix composites (MMCs). Matrix cracking, fibre failure, fibre bridging and interfacial debonding have been suggested as being the dominant factors in fatigue crack growth of MMCs. The FDM has been used to provide information regarding the contribution of these mechanisms to fatigue failure and their dependency on load history. The application of FDM is shown not only to define design limits but also to provide vital information for maintenance engineering.

Erosion resistance of continuously reinforced SiC–Ti-based metal matrix composites by a SiC/water slurry jet

The erosion of a continuously reinforced SiC (Sigma 1140 plus)/Ti–6Al–4V composite was investigated with a SiC/water slurry jet at various angles on a plane perpendicular to the direction of the reinforcement. The results demonstrate the combination of both ceramic and metallic properties. Both the low-angle erosion resistance of ceramics as well as the high-angle resistance of a metallic alloy lead to an overall reduction in erosion rate at the various angles. Ti/SiC composite shows the best erosive wear resistance indicating that the combination effect between ductile Ti-based matrix and high strength SiC fibre for continuously fibre-reinforced Ti-based metal matrix composites (MMCs) plays a key role in increasing the erosive resistance. To gain a better understanding of the combination and synergistic enhancement of erosion resistance for two components in SiC/Ti composite materials, a shadowing effect and effect of reducing impact energy on SiC fibre during erosion are discussed. A simple theoretical model based on experimental data and a modified inverse rule-of-mixtures averaging law of erosion resistance for SiC fibre-reinforced MMCs are discussed.

Investigation of interfacial reactivity in composite materials

The chemical vapor deposition technique has been used for the experimental simulation of the interfacial reactions in titanium matrix, silicon carbide reinforced, metal matrix composites (MMCs). Silicon and/or carbon containing thin films have been deposited on titanium substrates. The resulting diffusion couples have been given long term, high temperature treatments corresponding to operating conditions at the limits of Ti-based MMCs. The interfacial microstructures produced by these treatments have been investigated by different techniques and were successfully compared to those ones in the real Ti matrix MMCs. This new approach allows for a rapid, economic and easy-to-use evaluation technique and contributes to the optimization of the interfacial characteristics in composite materials.

MODELLING THE CONDITIONS FOR FATIGUE FAILURE IN METAL MATRIX COMPOSITES

Abstract— An investigation on the fatigue crack growth (FCG) and fatigue failure in metal matrix composites (MMCs) has been conducted using a model based on micromechanical elasto-plastic fracture mechanics (EPFM) principles. To evaluate the model, comparisons between experimental and predicted fatigue life have been made for two silicon carbide strengthened (SCS)-6/Ti-based MMCs. Conditions for crack arrest and crack instability have also been considered in order to define the fatigue damage limits. Crack arrest occurs from the added effects of fibre bridging and the constraint provided by the fibre on matrix microplasticity, while crack instability is achieved when the fibre constraint effect is minimum and the fatigue resistance of the material is reduced due to the accumulation of fatigue damage. Comparisons of the predicted fatigue damage limits with experimental results show good agreement which underlines the usefulness of a microstructural fracture mechanics model.

Functionally graded coatings on SiC fibres for protection in Ti-based metal matrix composites

The incorporation of SiC fibers in Ti-based alloys, has led to the development of high strength, low density and high creep resistant properties of titanium-based metal matrix composites (Ti-MMCs). These composites have applications in the aerospace industry as structural materials for aerojet components and compressor blades. The processing of Ti-based composites usually involves a consolidation stage using diffusion bonding or hot isostatic pressing where the consolidation temperatures are in excess of 800 C for a significant period of time. Severe interdiffusion and chemical reactions between the SiC and Ti-alloy matrices occur under such processing conditions, leading to the formation of brittle reaction layer and deterioration of the mechanical properties of the composites. In addition, the SiC/Ti interfacial reactions can also occur during in service if the operating temperature is above 700 C. A variety of approaches has been examined to prevent or reduce the SiC/Ti interfacial reactions in MMCs at elevated temperatures during material manufacturing and in service. Coating of the SiC fibers prior to incorporation into the Ti matrices seems to be the most viable approach to overcome this technical problem. This has prompted the development of functionally graded coatings onto SiC fibers. Functionally graded coating consists a systematicmore » but continuous variation in the composition and microstructure across the coating thickness, resulting in a gradual change in properties. Consequently, this has led to the distinct multifunction characteristics. This work describes the influence of functionally graded coatings of C/TiC/(Ti,C)/Ti in preserving the surface integrity and strength of the as-received SiC fibers, and effectiveness to prevent deleterious reaction with Ti-matrix as compared with the unprotected SiC fibers.« less

Phase diagrams of Ti-AL-C, Ti-Y-O, Nb-Y-O, and Nb-Al-O at 1100 °C

To develop suitable coating materials for A12O3 fibers used in Ti-based metal-matrix composites, the phase diagrams of Ti-Al-C, Ti-Y-O, Nb-Y-O, and Nb-Al-0 at 1100 °C were studied. The phase equilibrium samples were prepared by hot isostatic press (HIP), annealed, and then examined by x-ray diffraction (XRD). In the Al-Ti-C ternary, the present study was concentrated on the Ti-rich corner involving Ti, TiC, α2Ti3A1, and the ternary Pphase (T3AlC). The results show that at 1100 °C, β-(Ti, Al) is in equilibrium with TiC, but not in equilibrium with the Pphase as suggested by Schuster et al. In the Ti-Y-O, Nb-Y-O, and Nb-Al-0 ternary systems, the present study shows that Ti-Y2O3, Nb-Y2O3, and Nb-Al2O3 are in equilibrium at 1100 °C.

Interface microstructures in Ti-based composites using TiB 2/C-coated and uncoated SiC f after short-term thermal exposure

The extent of interfacial reaction after short-term thermal exposure during vacuum plasma spraying ( vps) and vacuum hot-pressing ( vhp) of Ti-based metal-matrix composites ( mmcs) using TiB 2/C-coated and uncoated SiC fibres has been investigated by a combination of scanning and transmission electron microscopies. There is no interfacial reaction after short-term thermal exposure during vps manufacture of SiC f/Ti mmcs using either TiB 2/C-coated or uncoated SiC f. There is only limited interfacial reaction after short-term thermal exposure during vhp manufacture of SiC f/Ti-6Al-4V mmcs using TiB 2/C-coated SiC f. In the initial stage of the interfacial reaction, TiB needles are formed by preferential nucleation and growth at β particles and grain boundaries in the Ti-6Al-4V matrix.

Materials research at The University of Birmingham

The lecture on which this paper is based was presented at the Birmingham meeting on 8 December 1989 to mark the year of Sir Alan Cottrell's 70th birthday. The paper aims to relate the early foundations laid in part by Sir Alan to the recent award to The University of Birmingham of the Interdisciplinary Research Centre (IRC) in Materials for High Performance Applications. The significance of one of Sir Alan's main interests, the application of dislocation concepts to important materials, is illustrated by examining some recent work on melt spun Al alloys and on Ti based metal matrix composites. This work has been carried out in the School of Metallurgy and Materials at Birmingham and is illustrative of much of the current microstructural work in the School.MST/1313

Materials research at The University of Birmingham

The lecture on which this paper is based was presented at the Birmingham meeting on 8 December 1989 to mark the year of Sir Alan Cottrell's 70th birthday. The paper aims to relate the early foundations laid in part by Sir Alan to the recent award to The University of Birmingham of the Interdisciplinary Research Centre (IRC) in Materials for High Performance Applications. The significance of one of Sir Alan's main interests, the application of dislocation concepts to important materials, is illustrated by examining some recent work on melt spun Al alloys and on Ti based metal matrix composites. This work has been carried out in the School of Metallurgy and Materials at Birmingham and is illustrative of much of the current microstructural work in the School.MST/1313