Microstructure Of TiC Research Articles

The Microstructures of TiC–Ti5Si3-Reinforced Cu Matrix Composites Prepared by Ti–SiC Reaction

In this work, the TiC and Ti5Si3-reinforced Cu matrix composites with different contents were successfully prepared through Ti–SiC reaction in Cu melts; accordingly, the microstructures of them were studied, and the hardness of the composites was tested. It is found that the synthesized TiC are granular, with a size ranging from 0.5 μm to 3 μm, while the Ti5Si3 are rod-like hexagonal prisms with a diameter of about 1 μm and a length-to-diameter ratio of about 5~25. In addition, it is noticed that many Ti5Si3 rods are actually Cu@Ti5Si3 core–shell structure rods. TiC and Ti5Si3 alternately distribute in the Cu matrix to form the hybrid reinforcement system. With the increase in Ti–SiC content, the TiC particles, Ti5Si3 rods and Cu@Ti5Si3 increased obviously, and the solid skeleton structure of TiC–Ti5Si3 was formed. The hardness of the composites was 2.2 to 2.74 times greater than that of the as-cast pure copper. It is deduced that, compared to the composites reinforced by either TiC or Ti5Si3, the formation of the TiC–Ti5Si3 hybrid system is more helpful for improving the properties of the composites due to the different morphologies of TiC and Ti5Si3.

Fabrication of (Ti-Al-Si)/(Ti-C)/Ti – layered alloy by SHS pressing

A metal-carbide-intermetallic material based on combustion products of the layer system (Ti-Al-Si)/(Ti-C)/Ti was for the first time obtained with the help of self-propagating high-temperature synthesis (SHS) combined with pressing. Exothermic synthesis from elementary powders was carried out at a pressure of 10 MPa, and pressing of the hot synthesis product was carried out at a pressure of 100 MPa. It has been shown that SHS pressing contributes to the formation of permanent joints of «metal/carbide/intermetallic» layers. The main features of microstructure formation, phase composition, and strength properties of transition zones at the boundary between reacting SHS compositions, Ti-C and Ti-Al-Si and Ti-metal substrate are investigated. It is shown that during SHS reaction, a homogeneous microstructure of Ti-C and Ti-Al-Si layers with an insignificant content of cracks and pores is formed. The thickness of the transition zone between the layers was at least 15 µm. The main phase formed in the combustion product of Ti-Al-Si layer is, according to the results of X-ray phase analysis, triple phase Ti20Al3Si9, the content of which, calculated by the Rietveld method, was at least 87 wt. %. In addition, the combustion product contains a secondary phase of Ti3Al in the amount of 13 wt. %. The energy dispersion analysis revealed that diffusion of aluminium through the titanium carbide layer into the titanium substrate to a depth of approx. 30 µm is observed. Microhardness value of the combustion product of Ti-Al-Si layer was about 10 GPa. The rectilinear nature of crack propagation in the synthesized combustion product of Ti-Al-Si layer, as well as the Palmquist crack resistance coefficient varying within 5.1-5.7 MPa·m1/2, indicate the fragility of the material.

Formability, Phase Composition, and Microstructure of TiC–(5–50 wt %) NiCr–Based Materials Obtained by Free SHS Compression

Formability, Phase Composition, and Microstructure of TiC–(5–50 wt %) NiCr–Based Materials Obtained by Free SHS Compression

Influence of Y2O3 addition on the microstructure of TiC reinforced Ti-based composite coating prepared by laser cladding

TiC reinforced Ti-based composite coatings were prepared on the Ti6Al4V surface via laser cladding with Ti6Al4V/NiCr-Cr 3 C 2 /Y 2 O 3 mixed powders. Influence of Y 2 O 3 on forming quality and microstructure of composite coatings was investigated systematically. The cracks were eliminated completely and the number of pores was drastically minimised when 2 wt% Y 2 O 3 was added. In addition, the reinforcement TiC and the matrix sloid solution β-Ti were the main precipitated phases within the coating. The addition of Y 2 O 3 inhibited the generation of Ti 2 Ni at the grain boundary, however, promoted the generation of Cr 1.93 Ti 1.07 in the coating. With the addition of Y 2 O 3 , the dendrites became largely developed and a large number of tertiary dendrites were found. Besides, a more obvious regional segregation appeared in the distribution of Ni and Cr elements in the coating with 2 wt% Y 2 O 3 . Furthermore, some nano-sized β-Ti were distributed on the surface of small TiC particles in both coatings. Combined with the theoretical analysis of the two-dimensional mismatch degree, the β-Ti and TiC interface exhibited a semi-coherent relationship. Therefore, β-Ti can nucleate with TiC as the heterogeneous nucleation matrix. In the meanwhile, there was a certain dependent growth relationship between the β-Ti and TiC. • Y 2 O 3 addition eliminated cracks completely and reduced porosity of the coating. • Y 2 O 3 addition led to sufficient growth of the developed dendrite TiC. • Irregular Ti 2 Ni disappeared and Cr 1.93 Ti 1.07 precipitated in coating with Y 2 O 3 . • Y 2 O 3 addition resulted in severe regional segregation of Cr and Ni. • β-Ti can nucleate with TiC as the heterogeneous nucleation center.

Influence on TiC microstructure from different synthesis processes in the Cu–Ti–SiC system

In this study, the formation processes of TiC in a Cu–Ti–SiC system following the addition of a Ti–SiC mixture into a Cu melt were studied by analyzing the reaction intermediates, and the influence of the synthesis processes on the TiC microstructure was examined. It is found that, upon the addition of Ti–SiC into the Cu melt, the reaction of Ti and Cu to form a Cu–Ti liquid phase occurred first, followed by the reaction between liquid Ti, denoted as Ti(l), and SiC. However, the Ti(l)–SiC reaction processes vary depending on the reaction conditions and significantly influence the microstructures of the TiC particles, especially their dispersion in the Cu matrix. Under certain conditions, such as a lower reaction temperature and larger SiC size, SiC does not directly react with Ti(l). It first transforms into graphite through the outward diffusion of Si; subsequently, the graphite phase reacts with Ti(l) to form TiC. In this case, the synthesized TiC particles tend to connect with each other to form agglomerates. Under conditions conducive to the direct reaction of the Ti(l)–SiC system, such as a higher reaction temperature and smaller SiC size, Ti(l) and SiC first react to form a Ti3SiC2 phase that then decomposes into TiCx and Ti–Si phases and eventually transforms into TiCy (x > y) and amorphous or crystalline Si. In this case, the formed Ti–Si or Si phase can prevent the agglomeration of TiC particles, leading to their more uniform distribution in the prepared Cu matrix composite.

In situ synthesized Ti2AlNb-based composites produced by selective laser melting by addition of SiC-whiskers

Ti2AlNb-based composites are attractive advanced materials for light-weight aero-space applications at high service temperatures since titanium orthorhombic alloys demonstrate an attractive combination of mechanical properties, low density, and are suitable for matrix materials. Additive Manufacturing is a promising way of producing SiC/Ti2AlNb composites because it offers a possibility to produce parts with a high degree of design-freedom and good mechanical properties. In this work, Ti2AlNb-based alloy powder was blended with 0–15 vol% SiC whiskers and used in Selective Laser Melting process with high-temperature substrate preheating to produce crack-free Ti2AlNb-based composites. Addition of SiC whiskers resulted in in situ formation of TiC phase and B2/β-grain refinement resulting in Ti2AlNb + B2 + TiC microstructure with microhardness up to 711 ± 15 HV1.0.

Effects of Process Parameters on Geometrical Characteristics and Microstructure of TiC Particle‐Reinforced Co50 Alloy by Laser Cladding

Laser cladding of Co50 alloy coating and Co50 composite coatings doped with 10, 20, and 30 wt.% TiC particles was performed on the H13 steel surface. The effects of TiC concentration on the phase composition, microstructure, and microhardness of the coatings were studied. The results indicated that, in 10% TiC coating, the “bright band” is a quite flat‐growth tissue, while with 20% TiC, the “white bright band” contains a large amount of black TiC particles. The composite coating Co50, 10% TiC, and 20% TiC samples can clearly distinguish the cladding zone, bonding zone, and heat‐affected zone, and a good metallurgical bond is formed between the coating and the substrate. The 30% TiC coating and the substrate are not well bonded, which is attributed to the high TiC content in the coating; however, it has the best surface morphology, and there is no porosity on the surface. 10% TiC coatings have poor surface quality, show a spraying material phenomenon on two side edges which is quite serious, and a lot of porosity on the surface of the coating. In addition, 10% TiC coating includes the original TiC particles and primary TiC particles that are precipitated in situ from the liquid phase during solidification; 20% TiC coating indicates a large amount of TiC in the form of cross petals and twigs, and the figure points out that TiC exists like a large number of diffusely distributed spherical structures in the 30% TiC coating. The coatings of TiC/Co composite with less than 20% TiC showed good metallurgical bonding characteristics with the H13 steel surface.

Characterization of TiC and TiB2 reinforced Nickel Aluminide (NiAl) based metal matrix composites cast by in situ vacuum suction arc melting

The development of materials with high temperature performance are progressively increasing towards the new generation alloys for better wear and oxidation resistance, extending service life and economical production methods. In this study, in addition to NiAl, NiAl composites reinforced with TiC or TiB2 was produced and characterized. Ni, Al, TiC and TiB2 powders are compacted and subsequently remelted by vacuum suction arc melting at atmospheric pressure. TiC and TiB2 additions are in the range 0.5, 1, 2, 4 and 8 wt %. The samples were obtained in the form of bar and metallographic examination was made in order to characterize the specimens produced. The types of phases, microstructure and their hardness were investigated by XRD, Scanning Electron Microscope and microhardness test.Studies showed that all samples consisting of single-phase matrix and the TiC/TiB2 particles remain in most cases insoluble or re-formed in the matrix. Hardness values vary according to the amount of increasing second phase particles. Although both additions generate similar results in hardness, the microstructure of TiC reinforced samples resulted in the second phase structure with a spherical shape while TiB2 reinforced samples resulted in rod-like structure. Heat treated specimens showed a dramatic change in microstructural and physical properties.

Effect of Cu-Ti-C reaction composition on reinforcing particles size of TiC x /Cu composites

TiC x /Cu composites were fabricated by combustion synthesis and hot press technology. Using XRD, SEM, EDS, FESEM analysis methods, the effects of various carbon sources and different Cu contents on the microstructures of TiC x /Cu composites and the size of TiC x particles were investigated. Results showed that TiC x reinforcing particles size increases with decreasing Cu content in Cu-Ti-C reaction system. With carbon nanotubes (carbon black) serving as carbon source, the generated TiC x particles size transits from nanometer to submicron when Cu content corresponding to the reaction system is reduced to 60 vol% (70 vol%); while graphite serves as carbon source, there is no clear limiting concentration. C particles with smaller size, larger specific surface area and better distribution result in finer TiC x particles, which is more beneficial to generating nano-sized TiC x /Cu composites.

Automated Method for the Evaluation of the Dimensional Characteristics of Microstructural Components of Hard Alloys Based on TiC–VC–Nano-WC

We develop automated method aimed at the evaluation of the parameters of the annular microstructure of TiC–VC–nano-WC–NiCr hard alloys. The software package is written in the C ++ 98 standard language with the use of cross-platform programming paradigms. For the determination of the bulk fractions of the main structural components of alloys and the sizes of carbide grains, we use the main concepts of stereometric metallography.

Evaluation of microstructure and wear properties of Ti-6Al-4V alloy plasma carbonized at different temperatures

Ti-6Al-4V (TC4) alloys were plasma carbonized at different temperatures (900, 950, and 1 000 °C) for duration of 3 h. Graphite rod was employed as carbon supplier to avoid the hydrogen brittleness which is ubiquitous in traditional gas carbonizing process. Two distinguished structures including a thin compound layer (carbides layer) and a thick layer with the mixed microstructure of TiC and the α-Ti in carburing layer were formed during carburizing. Furthermore, it was found that the microstructure and the properties of TC4 alloy were significantly related to the carbonizing temperature. The specimen plasma carbonized at 950 °C obtained maximum value both in the hardness and wear resistance.

Effect of NiAl content on phases and microstructures of TiC–TiB2–NiAl composites fabricated by reaction synthesis

TiC–TiB2–NiAl composites were fabricated by self-propagating high temperature reaction synthesis(SHS) with Ti, B4C, Ni and Al powders as raw materials. The effects of NiAl content on phase constituents and microstructures were investigated. The results show that the reaction products are composed of TiB2, TiC and NiAl. The content of NiAl increases with the adding of Ni+Al in green compacts. TiB2, TiC and NiAl grains present in different shapes in the matrix, TiB2 being in hexagonal or rectangular shapes, TiC in spherical shapes, and NiAl squeezed into the gaps of TiC and TiB2 grains. With the increase of NiAl content, the grains of TiC–TiB2–NiAl composites are refined, their density and compressive strength are improved, and the shapes of TiC grains become spherical instead of irregular ones. Finally, the fracture mechanism of the composites transforms from intergranular fracture mode to the compounded fracture mode of intergranular fracture and transgranular fracture.

Processing of TiC-CNT Hybrid Composite Coating on Low Alloy Steel Using TIG Torch Technique

In the present study, a surface layer of TiC-CNT hybrid compositecoating has been developed on low alloy steel (LAS) by using powder preplacement and tungsten inert gas (TIG) torch melting techniques.The weighed powder mixture with the content of 1.0 mg per millimeter square area and containing TiC-4wt. % CNT particles was preplaced on LAS surfaces using a suitable binder and then melted under the TIG arc with an operating current of 100 A and energy input of 1440 J/mm. The microstructural and microhardness characteristics of the processed composites coating were analyzed using SEM, EDXand Vickers microhardness testers. Under the melting condition used in this investigation, the arc completely dissolved the composite powder mixture that resolidifiedinto a melt track with radial marks and smooth surfaces. Themelt cross sections were hemispherical in shape and produced 1 mm deep hard coating layer which were free from porosity and cracks. SEM micrographs TiC-CNT hybrid coated surface glazed at 100A consists of fineprecipitated TiC in form globular and cubic dendrites and this is the reason for hardness increment to an average of three times greater than that of substrate value. The result obtained indicated that TIG arc melting process is applicable to generate resolidified layer of precipitated TiC microstructure with uniformly distribution in the coating region.

Microstructure of TiC Produced by Laser Cladding Using Ni + C Mixing Powder on Ti–6Al–4V Substrate

Microstructure of TiC Produced by Laser Cladding Using Ni + C Mixing Powder on Ti–6Al–4V Substrate

Solidification observations of vacuum arc melting processed Fe–Al–TiC composites: TiC precipitation mechanisms

Abstract Fe22Al–5 wt.%TiC composite material has successfully synthesised by Vacuum Arc Melting (VAM) process. TiC crystals were formed by a dissolution–reprecipitation process of TiC powder added as precursor material. The solidification cooling rate alters the growth morphologies of the precipitated crystals. Jackson's classical crystal nucleation and growth theories were facilitated in order to explain the final TiC microstructure.

Microstructure of TiC/Nb-Ni Cermets Cladding Layer

This paper reports an investigation of the effect of Nb additions on the microstructure of TiC–Ni cermets, which is prepared by plasma cladding technique. The composition of the cermets cladding layer was observed by scanning electron microscope (SEM) in combination with energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) analysis was carried out for phase identification. The microstructure has a trend to become finer with the increase of Nb additions, however, when the Nb addition goes to 15 wt%, the ceramic particles become much bigger and cause large amounts of cracks. Then the component variation of different parts of the ceramic particle was analyzed using the EDS, and explained the reason of the variation and why the rim structure wasn't formed.

The surface microstructure of TiC-(Ti,W)C-WC-Ni cermets sintered in a nitrogen atmosphere

The effects of nitrogen and a solid-solution carbide on the surface microstructure of TiC-(Ti,W)C-WC-Ni cermets were investigated. The binder enrichment layer with the cubic carbide was observed at the surface, the formation of which is attributed to the concentration gradient of nitrogen and constituent elements. This tendency is found to decrease as the dissolution rate increases when nano-sized TiC was employed. Coarsening behavior and the formation of a discrete layer were studied as a function of (Ti 0.93W 0.07)C carbide content and nitrogen pressure. The results were interpreted in terms of the relative thermodynamic stability of the carbide phases in the system.

In-situ synthesis and microstructure of TiC–Fe36Ni composite coatings by reactive detonation-gun spraying

A kind of Ti–Fe–Ni–C compound powder was prepared by a novel precursor pyrolysis process using ferro-titanium, carbonyl nickel powder and sucrose as raw materials. The powder had a very compact structure and was uniform in particle size. The TiC–Fe36Ni composite coatings were simultaneously in-situ synthesized by Reactive Detonation-gun Spraying (RDS) using these Ti-Fe-Ni-C compound powders. The coatings presented typical morphology of thermal spraying coatings with two different areas: one was the area of TiC distribution where the round fine TiC particles (from 300nm to 1μm) were dispersed in the Fe36Ni alloy matrix; the other was the area of TiC accumulation (from 2 to 4μm). The surface hardness of the composite coating reached about 94 ± 2(HR15N).

Synthesis of submicrocrystalline TiCx–Al2O3 composites by mechanically-activated pressure-assisted self-propagating high-temperature synthesis technique

TiCx–Al2O3 composites have been synthesized by pressure-assisted combustion synthesis of (Ti + C + Al2O3) reactant powder. Different alumina contents (10–40 vol%) have been investigated to study the dilution effect on TiC microstructure. A mechanical method and a mixed chemical/mechanical method have been used to obtain (Ti + C + Al2O3) powder mixtures with different alumina distributions. Scanning electron microscopy (SEM) observations of these mixtures show that alumina is distributed inside micrometric (Ti + C) aggregates for the first method whereas alumina is located around (Ti + C) aggregates for the second one. X-ray diffraction (XRD) and SEM analyses of the composites indicate that TiCx is substoichiometric in carbon and mainly consists of submicrometric grains. A distribution of Al2O3 inside (Ti + C) aggregates is more efficient to reduce TiC grain size. For the 40 vol% Al2O3 diluted (Ti + C) mixture prepared from the mechanical route, TiCx nanocrystallites have been successfully stabilized, which demonstrates that the addition of Al2O3 diluent in a (Ti + C) mixture can be efficiently used to inhibit grain growth.

Microstructure and fracture toughness of TiC–ZrC–WC–Mo–Ni cermets

Abstract TiC-based cermets have advantages such as lower friction coefficient and higher oxidation resistance compared with WC-based cemented carbides. However, the brittleness is still an unavoidable limitation for their utilizations. Microstructure of TiC– x ZrC–15WC–14Mo–20Ni–1C cermets with different ZrC contents was studied by using X-ray diffractometry (XRD), scanning electron microscopy (SEM) in combination with energy dispersive spectrometer (EDS). The experimental results show that ZrC dissolved in the cermets and formed solid solutions of (Zr, Ti, Mo, W)C. The bright and gray coreless grains have been regarded as beneficial for the toughness of the cermets.