Powder Mixtures Of Ti Research Articles

Experimental Verification of the Mechanism of Formation of Condensed Products from a Powder Mixture of Ti–B–TiH2 in the Course of Self-Propagating High-Temperature Synthesis

Experimental Verification of the Mechanism of Formation of Condensed Products from a Powder Mixture of Ti–B–TiH2 in the Course of Self-Propagating High-Temperature Synthesis

Electromagnetic characterization of MAX phase and MXene in Ti–Al–C ternary system

The present paper set out to investigate the synthesis and electromagnetic characterization of Ti3AlC2 MAX phase and Ti3C2Tx MXene in Ti–Al–C ternary system. In this regard, Ti3AlC2 MAX phase was synthesized using mechanical milling process of TiC, Al, and Ti powder mixtures based on 2TiC–Al–Ti + xAl (x = 0, 0.25, 0.5, 0.75 and 1). The HF acidic etching was also employed to synthesize the Ti3C2Tx MXene. Structural and electromagnetic characterizations of the prepared samples were conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vector network analyzer. The obtained results point to the impossibility of the formation of Ti3AlC2 single-phase structure in stoichiometric system. In other word, development of the Ti3AlC2 single-phase structure is only possible in non-stoichiometric 2TiC–2Al–Ti system. The minimum reflection losses of the prepared Ti3AlC2 MAX phase was estimated to be around −30.73 dB at the matching frequency of 15.25 GHz. The results further revealed that the etching time affects electromagnetic behavior of the MXene. That is, an increase in the etching time brings about a change in the reflection loss (RL) from −24.17 to −5.69 dB within the frequency range of 1–18 GHz.

Production of CuNiSi Composites by Powder Metallurgy Method: Effects of Ti on the Microstructural and Corrosion Properties

In this study, composite samples were produced by supplementing the CuNiSi powder mixture with Ti particles at different weight ratios using the powder metallurgy (PM) method. The prepared CuNiSi and Ti powder mixtures were turned into pellets by cold pressing under 500 MPa pressure. The pelletized samples were subjected to sintering in an atmosphere-controlled oven at 900 ℃ for 2 hours. Scanning electron microscopy (SEM-EDS), SEM-Mapping and corrosion experiments were performed to determine the microstructures of the produced samples. From the microstructure results, it was determined that Ti particles were distributed homogeneously within the structure. As the amount of Ti increased, the resistance of the composite to corrosion increased. In addition to that, as the amount of Ti increased, the resistance of the composite to corrosion decreased.

Microstructure evolution and reaction mechanism of reactive plasma sprayed Ti–C–N coatings

This investigation focuses on the feasibility of the reaction synthesis of Ti–C–N phase using plasma spraying powder mixture of Ti and graphite under nitrogen ion flame flow. To regularize the microstructure and properties of the sprayed Ti–C–N coating, the microstructure evolution of the Ti-graphite-N2 system was analyzed based on water quenching tests. The reaction pathway of the Ti-graphite-N2 system has been investigated by thermodynamic calculations and thermal analysis, revealing the mechanisms of the reaction during plasma spraying. The results show that the as-deposited coatings exhibit a typical layered structure consisting mainly of TiCxNy and TiO2. The quenched powders exhibit a melting process from irregular particles to smooth spherical particles, forming complete droplets with increasing spray distance. Based on phase evolution of the quenched powders and the thermal analysis of Ti powders or Ti/graphite powders under N2/Ar atmosphere, it found that the Ti powder can reacted with graphite or N2 by solid-solid or solid-gas reaction to form TiCx and TiNy, and TiNy can be formed preferentially as compared with TiCx phase. As the spraying distance increases, the Ti and graphite reactions are enhanced, and a pronounced TiCx phase can be detected once a large liquid Ti phase is formed. As the spray distance increases, formed TiNy and TiCx phases aggregate into droplets and rapidly transform into TiCxNy phase by solid-solution reactions. In addition, titanium oxide coexists in lamellae of Ti–C–N coatings due to the absorption and dissociation of O₂ from the atmosphere at the droplet surface.

Effect of Ti additive and preparation procedure on the temperature and decomposition kinetics of the MgH2 phase in the synthesized mechanicals alloys

The mechanical alloy Mg + 10 wt.% Ti and two mechanical alloys MgH2 + 10 wt.% Ti were synthesized by a reactive mechanical alloying (RMA) method, but in different ways. The influence of doping and the preparation procedure of mechanical alloys (MAs) on thehydrogen sorption properties, temperature and decomposition kinetics of their MgH2 phase was investigated by isobaric thermodesorption spectroscopy at a constant hydrogen pressure of 0.1 MPa. The desorption kinetics of the milled MgH2 + 10 wt.% Ti are faster than in the case of the ball milled Mg + 10 wt.% Ti. It was found that the manner of obtaining a mechanical alloys by reactive milling of MgH2 +10 wt. % Ti powder mixture rather than Mg +10 wt. % Ti powder mixture to improve the kinetic characteristics. The role of Ti as an alloying element in improving the hydrogen desorption kinetics of МAs obtained by various preparation procedures was studied. The stabilizing effect of Ti on the nanocrystalline structure and growth of the crystallites (grains) of the MgH2 phase during the cycling was also evaluated. It has been established the practical absence of the influence of Ti additive and the manner of obtaining MAs on the its thermodynamic stability.

INCREASING THE RESOURCE OF VEHICLE PARTS BY COMPOSITE MATERIALS DURING THEIR RESTORATION REPAIR

To restore machine parts used quite a large range of materials in the form of wire, powders, flexible cords, etc. However, it is not always possible to provide the required resource for the restoration of parts working in abrasive and corrosive environments. One of the modern directions of increasing the wear resistance and other properties of reducing coatings is the use of composite materials. This paper presents the results of research on the development of a composite modifying material to control the properties of reducing coatings based on commercially available powder material PG- 10N-01. It is shown that the developed composite material obtained using the SHS process from a powder mixture of Ti+C+SiO2+Al2O3+Fe2O3+Al+PT-NA-01 provides a higher (1.65 times) abrasive resistance of the deposited alloy coating PG-10N-01 when modifying its composite material in the amount of 20%.

Electrochemical hydrogenation of Ti–Ni powder mechanochemically alloyed with titanium

The paper reports the results of the study aimed to increase the Ti2Ni phase content in Ti–Ni powder by mechanochemical alloying with titanium and subsequent heat treatment. The interaction of the alloyed Ti–Ni powder with hydrogen was investigated. It is shown that before mechanochemical alloying the phase composition of Ti–Ni powder included three phases: TiNi (B2, B19’), Ti2Ni, and Ni3Ti. After mechanochemical alloying followed by heat treatment, Ti–Ni powder contained TiNi (B2, B19’) and Ti2Ni phases, where the latter phase was of different genesis. Ti2Ni (I) phase was present in Ti–Ni powder before mechanochemical alloying; its unit cell size after alloying with titanium remained unchanged and was equal to 1.1283 ± 5 × 10−4 nm Ti2Ni (II) phase was formed during mechanochemical alloying; its lattice parameter decreased as the Ti content in Ti–Ni powder during alloying increased. Electrochemical hydrogenation of the Ti–Ni (85 wt%) – Ti (15 wt%) powder mixture increased the cell size of both Ti2Ni (I) and Ti2Ni (II), which indicates the interaction of hydrogen with both Ti2Ni phases. The Ti2Ni (I) cell volume increased by 0.3% due to solid solution formation, and the Ti2Ni (II) cell volume increased by 17.6% due to hydride formation. The Ti2Ni (II) phase formed by mechanochemical alloying is more prone to interact with hydrogen with the formation of Ti2NiHx hydride than with the Ti2Ni (I) phase present in Ti–Ni powder before alloying. The number of hydrogen atoms in chemical formulas of Ti2Ni (II)-based hydride was determined. Hydrogenation of the Ti–Ni (85 wt%) – Ti (15 wt%) powder mixture for 90 min caused formation of Ti2NiH1.9 hydride; 360 min hydrogenation yielded Ti2NiH2.8 hydride.

Integrated high strength and high toughness induced by elongated TiB2 grains in reactive sintered TiB2–TiC–SiC ceramics

AbstractAlthough the addition of other phases into TiB2 matrix to form ceramic composites has been widely used to improve the mechanical properties of monolithic TiB2 ceramics, it is still difficult to greatly enhance the flexural strength and fracture toughness simultaneously. In this work, TiB2–TiC–SiC composites were successfully prepared by reactive spark plasma sintering of Ti3SiC2–B4C–Ti powder mixtures. During the sintering process, TiB2 grains grew into an elongated morphology, endowing the composites with integrated high strength and high toughness. The growth mechanism of TiB2 grains was attributed to the evaporation–condensation kinetics induced by the presence of B2O3. These findings can accelerate the exploration of ceramic composites with excellent comprehensive properties.

Fabrication of Ni-Rich 58NiTi and 60NiTi from Elementally Blended Ni and Ti Powders by a Laser Powder Bed Fusion Technique: Their Printing, Homogenization and Densification.

Compared to the equiatomic or near-equiatomic NiTinol alloys, Ni-rich NiTi alloys are suitable to be employed in structural applications as they exhibit higher hardness and are dimensionally stable. This research aimed to process two different grades of Ni-rich NiTi alloys, 58NiTi and 60NiTi, from Ni–Ti powder mixtures having about 58 wt.% and 60 wt.% Ni, respectively. This was performed by a laser powder bed fusion technique. At the first stage of this research, the printability of the used powder mixtures was investigated by applying different sets of printing parameters. Two appropriate sets were then selected to print the samples. Microstructural study of the printed parts revealed the existence of inhomogeneity in the microstructures. In addition, depending on the applied set of parameters, some amounts of cracks and pores were also present in the microstructure of these parts. Postprinting hot isostatic pressing procedures, performed at different temperatures, were developed to cause the reaction of phases, homogenize the parts, and possibly eliminate the existing flaws from the samples. Effects of these applied treatments on the microstructure, phase composition, density, dimensional integrity, and hardness of parts were sequentially studied. In essence, 58NiTi and 60NiTi parts having phase compositions complying with those of the equilibrium phase diagram were obtained in this research. However, the mentioned cracks and pores, formed in the microstructure of as-printed parts, could not be fully removed by postprocessing treatments.

Microstructure and tribological properties of in-situ TiC reinforced Ti2AlNb-based coatings by laser cladding

The TiC reinforced Ti2AlNb-based coatings were fabricated on the surface of Ti-6Al-4V using Ti, Al, and Nb powder mixtures with different NbC addition (0, 1.25, 2.5, and 5 wt%) by laser cladding to improve the mechanical behavior of Ti-6Al-4V. The effects of NbC on the morphology, microstructure evolution and mechanical properties of the TiC/Ti2AlNb coatings were studied systematically. Results revealed that the matrix phases of all coatings were mainly composed of lamellar O phase and B2 phase. TiC in situ formed effectively refined grains, in which the length of the B2 grains was reduced from 205.36 μm to 25.31 μm, and the O phase was reduced from 5 μm to <1 μm as the NbC addition increased from 0 wt% to 5 wt%. Mechanical properties illustrated that the coating with the NbC addition of 2.5 wt% had the highest microhardness with 575.6 HV0.2 and the smallest volume loss with 0.66 mm3 due to fine grain strengthening and dispersion strengthening of TiC. Compared to the Ti-6Al-4V substrate, the microhardness was increased by 1.64 times, and the volume loss was reduced to 30 %. Nevertheless, the mechanical properties of the coatings will exhibit a downward trend by adding excessive NbC (5 wt%), and the coarsening of the TiC could be used to explain this slight decrease.

Corrosion Resistance of Materials Obtained By Electron-Beam Cladding of Fe – Cr – Ni – Ti Powder Mixtures

Corrosion Resistance of Materials Obtained By Electron-Beam Cladding of Fe – Cr – Ni – Ti Powder Mixtures

Performance evaluation of TIG cladded in-situ TiC-TiB2 composite coating fabricated on AISI304 stainless steel

Tungsten inert gas (TIG) cladding is a surface modification technique used to deposit a coating with hard and resistance to wear material, which can improve the operational life of engineering components. In the present work, to improve the mechanical performance of AISI 304 stainless steel, in-situ TiC-TiB2 composite coating was fabricated through TIG cladding route by pre-placing Ti and B4C powder mixture at 3:1 wt ratio. The single line clad width and height was measured from the cross-sectional SEM images of the clad track. The microstructural analysis of the clad layer was accomplished through SEM images; however, EDS analysis was performed to study the distribution of different elements present in the clad layer. Almost a uniform clad layer with minor pores at the boundaries of the clad track was observed. The micro-hardness values variation towards the depth of the coating were evaluated for the clad layers deposited with different arc scanning speeds. Average value of micro-hardness was recorded between 800 and 1000 HV0.05, which was significantly higher than the substrate hardness.

Production of high-entropy Fe–Cr–Co–Ni–Ti alloy by mechanical alloying and spark plasma sintering of a powder mixture

A two-phase powder alloy based on substitutional solid solutions with BCC and FCC lattices was obtained by highintensity mechanical treatment (HMT) of a multicomponent Fe–Cr–Co–Ni–Ti powder mixture. Sample sections and particles of mixtures obtained were studied using an ultra high resolution field emission scanning electron microscope by scanning electron microscopy. XRD patterns of mixtures were recorded on the DRON 3 diffractometer with FeKα and CuKα radiation. It was found that after 10 minutes of HMT one intense superposition reflection remains on the XRD pattern with the angular position corresponding to Reflections 111 and 110 of phases with FCC and BCC lattices, respectively. A spark plasma sintering (SPS) method was used to obtain compact high-entropy material samples from the mixture after 90 minutes of HMT at 800 and 1000 °C. Their specific electrical resistance and density as well as the dependence of these properties on the sintering temperature were determined. It was demonstrated that the substitutional solid solution with the BCC lattice is probably enriched with titanium during the powder alloy SPS process.

Oxidation behavior of Al-doped Ti3SiC2-20 wt.%Ti5Si3 composite

In this work, an aluminum-doped Ti3SiC2-20 wt.% Ti5Si3 composite was prepared through reactive spark plasma sintering (SPS) from a powder mixture of Ti, SiC, C, and Al. The microstructure evolution of the formed oxide scales onto this composite were investigated in the temperature range of 1000–1400 °C in air. Up to 1200 °C, the exposed surfaces were highly protected by a continuous and dense α-Al2O3 layer with a good adherence that acts as a barrier diffusion. Above this temperature, the breakaway oxidation occurs, leading to an oxidation speed-up, which results in a thick oxide scale formation with low oxidation protective capacity. Scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), and Raman spectroscopy analysis of the oxide scales at different temperatures revealed that Al2TiO5 grain growth is the main deterioration factor of the protective α-Al2O3 layer. The oxidation kinetics of this composite at 1100 °C is comparable with that of the best MAX phases in terms of oxidation resistance, with a parabolic rate constant (Kp) of 3.08 × 10−10 kg2/m4s.

Identification and characterisation of a new orthorhombic Ti6Sn5O0.9 structure

The orthorhombic phase of Ti6Sn5 in the Ti-Sn binary system is regarded as a low-temperature or metastable phase. The motivation of the present study was to clarify the presence of this orthorhombic phase. This phase could not be synthesized by heating a mixture of Ti and Sn powder at 873 K, whereas single crystals of a novel suboxide, Ti6Sn5O0.88 (orthorhombic, a = 5.72790(10) Å, b = 9.1379(2) Å, c = 16.9275(3) Å, space group Immm), were obtained by heating powders of Ti, Sn, and TiO2 at 1273 K in an Ar atmosphere, followed by slow cooling. Crystal structure analysis of single-crystal X-ray diffraction data indicated that the O atoms are located at a 4 g site in the Ti tetrahedron of the orthorhombic Ti6Sn5 structure. An almost single-phase polycrystalline bulk sample of Ti6Sn5O0.9 was prepared by heating a compacted powder mixture of Ti, Sn, SnO2 at 1173 K. The bulk sample exhibited metallic electrical properties.

A study on the possibility to process dense 60NiTi from elementally blended Ni and Ti powders

This research aimed to process 60NiTi with a dense and homogeneous microstructure from a Ni–Ti powder mixture. It was noted that the optimum route, amongst the ones studied in this research, for obtaining parts having a homogeneous microstructure and the highest amount of relative density is as follows: The powder mixture being initially CIPed was sintered at 750 °C for a holding time of 8 h. To homogenize the microstructure and to obtain the required phases, a secondary sintering treatment was applied on samples cut from elementary sintered parts. After conducting this treatment at 1050 °C for 4 h, the formation of a homogeneous microstructure containing mainly NiTi, Ni3Ti and Ni3Ti2 phases was observed in the samples. However, the microstructures of these treated samples consisted of ∼34% porosity. Applying HIP treatments, under 180 MPa and for a holding time of 1 h, at different temperatures above the melting start temperature of the samples, treated by the secondary sintering procedure, successfully increased the density of parts. 1181 °C was the maximum temperature at which the parts could be treated without losing their dimensional integrity and parts with the highest relative density of ∼92% were obtained.

Study of the Influence of the Time of Mechanical Processing of Powder Mixture of Composition Ti – 25 wt. % TiN in a Planetary Mill on the Characteristics of Composite Particles

In this work, by the method of mechanical processing in a high-energy planetary mill of titanium powder (PTS – 1) and ceramic powder of titanium nitride, composite particles with a size of 10 to 100 μm were obtained, in the volume of which ultrafine particles of titanium nitride are distributed. It is assumed that the use of such particles in powder spraying by cold or thermal spray will increase the homogeneity of the distribution of refractory elements in the coating volume. Depending on the time of mechanical treatment of the powder mixture containing three weight fractions of ultrafine particles of titanium nitride, agglomerated composite particles were obtained. Their granulometric composition and surface morphology were studied; a map of the distribution of elements over the surface and volume of the particle material is obtained. It is noted that during mechanical processing of materials in a planetary mill, the behavior of titanium nitride particles is similar to the role of a surfactant. It is shown that the time of mechanical processing of the powder mixture for three minutes is optimal: composite particles have an average size of 38 microns; mass fraction of particles of fraction 20 – 90 μm more than 60 %.

Synthesis and Characterization of a Nearly Single Bulk Ti2AlN MAX Phase Obtained from Ti/AlN Powder Mixture through Spark Plasma Sintering.

MAX phases are an advanced class of ceramics based on ternary carbides or nitrides that combine some of the ceramic and metallic properties, which make them potential candidate materials for many engineering applications under severe conditions. The present work reports the successful synthesis of nearly single bulk Ti2AlN MAX phase (>98% purity) through solid-state reaction and from a Ti and AlN powder mixture in a molar ratio of 2:1 as starting materials. The mixture of Ti and AlN powders was subjected to reactive spark plasma sintering (SPS) under 30 MPa at 1200 °C and 1300 °C for 10 min in a vacuum atmosphere. It was found that the massive formation of Al2O3 particles at the grain boundaries during sintering inhibits the development of the Ti2AlN MAX phase in the outer zone of the samples. The effect of sintering temperature on the microstructure and mechanical properties of the Ti2AlN MAX phase was investigated and discussed.

Analysis of SiC mixture densification in explosive compaction

The paper presents the results of research into how the binder content and the Shockwave compression parameters affect SiC and Ti powder mixture densification in explosive compaction. The microstructure of the resulting compacted metal was studied by scanning electron microscopy. Phase and chemical composition was studied by X-ray crystallography and energy-dispersive analysis. It was found that at higher silicon carbide concentrations and higher powder heating temperatures, Shockwave compression reduced the residual porosity of the compacted metal to 2%. The microstructure was a carbide-silicon matrix with titanium inclusions. The obtained material matched the initial components in phase composition.

Formation of the Structure of Powder Materials Based on Silicon Carbide by Explosive Compaction

The possibility of producing powder composite materials in the SiC–Ti system by explosive compaction without subsequent sintering was studied. It was found that, under these conditions, the densification of SiC and Ti powder mixtures is due to the interparticle displacement and deformation of particles of the carbide phase. It was shown that the main condition for the consolidation is the heating of the initial powder mixture by shock-wave compression to temperatures above 780°C.