Volume Fraction Of TiC Research Articles

In-situ fabrication of TiC-Fe3Al cermet

Titanium carbide has high hardness, resistance to oxidation and abrasion while iron aluminide has proper ductility as well as good strength and excellent oxidation resistance up to high temperatures. Therefore, it can be expected TiC-iron aluminide cermet to have excellent mechanical properties as a cutting tool and a wear-resistance material. In this study, mechanical milling and hot press sintering processes were used to manufacture in-situ TiC-Fe3Al cermet, whose microstructure and mechanical properties were examined according to the changes in volume fraction of TiC and milling time. After 48h of milling each mechanically alloyed powder crystallized in a TiC and Fe3Al biphasic material. The milled powder was hot-pressed at 1250℃ and 50MPa for 30min to obtain sintered bodies also consisting of only TiC and Fe3Al phases. The hard phase, TiC, had a size of 100–300nm with overall uniform distribution decreasing as the volume fraction of TiC increased. The hardness of each sintered body showed a linearly increasing tendency according to the increase in TiC content, the hardness for 90vol% TiC cermet being as high as 1813Hv. On the other hand, the bending strength was 1800MPa and 1780MPa when TiC volume fraction was 50% and 70%, respectively, while it showed an abrupt decrease up to 580MPa at 90% TiC volume fraction. Fe3Al phase is effective to toughening of TiC-Fe3Al cermet and the volume fraction of Fe3Al phase significantly influences the bending strength of the cermet.

Room-temperature fracture toughness of MoSiBTiC alloys

Room-temperature fracture toughnesses of TiC-added Mo-Si-B alloys were evaluated for samples of three different compositions prepared using a conventional Ar arc-melting technique. The first alloy (TiCp) had a primary phase during solidification of NaCl-type TiC including an amount of Mo, with a Mo solid solution (Moss) volume fraction of approximately 49% and a TiC volume fraction of approximately 19%, while the volume fraction of Mo5SiB2 (T2) was approximately 31% and the remaining 1% was Mo2C including an amount of Ti. The second alloy (T2p) had a primary phase of T2, with volume fractions of Moss, TiC, Mo5SiB2 (T2), and Mo2C of approximately 38%, 4%, 45%, and 13%, respectively. The third alloy (Mop) had a primary phase of Moss, with volume fractions of Moss, TiC, Mo5SiB2 (T2), and Mo2C of approximately 55%, 8%, 32%, and 6%, respectively. Room-temperature fracture toughness was evaluated by three different bending tests using Chevron-notched specimens. Fracture toughness values obtained by the three methods were relatively close with good reproducibility. Consequently, the fracture toughness values of TiCp, T2p, and Mop were evaluated to be ∼15.2 MPa(m)1/2, ∼10.5 MPa(m)1/2, and ∼13.6 MPa(m)1/2, respectively. Fracture surface observations indicated that the Moss phase is subject to severe plastic deformation during the fracture process. The TiC phase was also noted to leave river patterns behind through crack propagation. These fractographic results suggest that not only the ductile-phase toughening by the Moss phase but also an extra-toughening mechanism by the TiC phase are responsible for the goodness of the room-temperature fracture toughness of the MoSiBTiC alloys.

Mechanical properties of hot-pressed SiC-TiC composites

SiC-TiC composites, with 0, 5, 10 and 20 vol.% of TiC, were sintered by the hot-pressing technique at temperature of 2000?C under argon atmosphere. SiC sintering process was activated by liquid phase created by the reaction between Al2O3 and Y2O3, in which it is possible to dissolve passivating oxide layers (SiO2 and TiO2) and partially SiC and TiC carbides. Microstructure observation and density measurements confirmed that the composites were dense with uniformly distributed components. Differences in thermal expansion coefficients between SiC and TiC led to complex stress state occurrence. These stresses combined with the liquid-derived separate phase between grains boundaries increased fracture toughness of the composites, which ranged from 5.8 to 6.3MPa?m0.5. Opposite to the bending strength, fracture toughness increased with the TiC volume fraction. By means of simulation of residual thermal stresses in the composites, it was found that with the increasing volume fraction of TiC, tensile stress in TiC grains is reduced simultaneously with strong rise of compressive stresses in the matrix.

Strengthening behavior of in situ-synthesized (TiC–TiB)/Ti composites by powder metallurgy and hot extrusion

Titanium matrix composites (TMCs) reinforced with in situ-formed TiC particles and TiB whiskers were prepared by reacting titanium and B4C via powder metallurgy and hot extrusion. The effect of the in situ-formed TiC–TiB hybrid reinforcements on the microstructure and mechanical behavior of the TMCs was investigated. TiB whiskers exhibited favorable alignment, orienting parallel to the deformation axis after hot extrusion, while TiC particles and TiB whiskers were distributed homogenously throughout the extruded composites. The synthesized TMCs with a 13.6% volume fraction of TiC–TiB hybrid reinforcements presented a σUTS of 1138MPa, representing a 74% improvement compared to pure titanium, and retained an acceptable elongation of 2.6%. The synergistic strengthening effect of TiC particles and TiB whiskers was investigated via in situ tensile observations based on the load-transfer mechanism between the titanium matrix and TiC–TiB reinforcements.

Evolution of microstructure and mechanical properties of in situ synthesized TiC–TiB2/CoCrCuFeNi high entropy alloy coatings

The aim of this paper was to explore a one-step in situ method to synthesize the TiC–TiB2 reinforced CoCrCuFeNi high entropy alloy composite coatings. In this method, the composite coatings were prepared by plasma transferred arc cladding process using Ti, B4C, Co, Cr, Cu, Fe, and Ni powder mixture as precursors. The effects of CoCrCuFeNi(Ti, B4C)x (x in molar ratio, 0.1≤x≤0.5) additions on the structure and mechanical properties of the coatings were investigated. For 0.1≤x≤0.2, the coatings induce the formation of face-centered cubic (FCC) and body-centered cubic (BCC) plus TiC structures. Further addition of x content (0.3≤x≤0.5), promotes high volume fraction of dual-phase TiC–TiB2 embedded in FCC and BCC matrix. There are also corresponding variations in mechanical properties with structural evolutions. For CoCrCuFeNi(Ti, B4C)0.1 coating, the nanohardness (H) and Young's modulus (E) are 4.19 and 234GPa, respectively. These properties are further improved as function of x content (H=9.14GPa and E=261GPa are achieved in CoCrCuFeNi(Ti, B4C)0.5 coating). The mechanical hardening is accompanied with an increase of the ratio of hardness to elastic modulus (H/E), the yield pressure (H3/E2) and the elastic recovery (η value). An attempt has been made to co-relate the wear resistance of the coatings with H/E ratio and η value.

Overlapping tracks processed by TIG melting TiC preplaced powder on low alloy steel surfaces

An overlapping composite track coating was produced on a steel surface by preplacing a 0·5 mm thick layer of TiC powder and then melting using a tungsten inert gas torch of constant energy input. The influence of the overlapping operation on preheating of the substrate, the dissolution of TiC particulates and the subsequent depth and hardness of the composite layer was analysed. The melt microstructure consisted of both undissolved and partially dissolved TiC particulates, together with a variety of morphologies and sizes of TiC particles precipitated during solidification. Preheating, resulting from the overlapping operation, occurred, producing additional melting of the TiC particulates and deeper melt depths but with a reduced volume fraction of TiC precipitates in the subsequent tracks. A maximum hardness of over 800 HV was developed in the composite layer. The high hardness was unevenly distributed in tracks melted at the initial and final stages, while it varied across the melt depths in other tracks.

Reaction sintering of SiC composites with in situ converted TiO2 to TiC

Binary SiC–TiO2 ceramic composite was fabricated using reaction pressureless sintering at temperatures ranging from 1825 to 1900 °C. The raw materials for the reaction process were TiO2 and carbon powders, where yttria (Y2O3) and alumina (Al2O3) were used as sintering aids. The SiC grain size and morphology were analyzed as a function of TiC volume fraction. The presence of TiC particles in the SiC matrix inhibited the exaggerated grain growth of the SiC grains and activated additional mass transport mechanisms. The SiC grains were found to be roughly equiaxed with very fine TiC particles preventing significant elongation. The role the TiC particles play in the densification of SiC was also discussed.

Microstructure and mechanical properties of P/M titanium matrix composites reinforced by in-situ synthesized TiC–TiB

Titanium matrix composites (TMCs) were prepared via reactive Ti-B4C system by powder metallurgy and hot extrusion route. The effect of the volume fraction of in-situ synthesized TiC particles and TiB whiskers on microstructure and mechanical behavior of TMCs were investigated. TiB whiskers showed favorable alignment oriented parallel to the deformation axis after hot extrusion; TiC particles and TiB whiskers distributed homogenously throughout the as-extruded composites. σUTS of the synthesized TMCs increased gradually from 654MPa to 1138MPa when the volume fractions of hybrid TiC and TiB were raised from zero to theoretical value of 13.6vol%; the elongation decreased from 32.4% to 2.6% correspondingly. The strengthening effect of in-situ formed TiC–TiB hybrid reinforcements at room and elevated temperature was studied based on the load-transfer mechanism between the titanium matrix and TiC–TiB reinforcements. It was found that synergistic of the TiC particle and TiB whisker showed beneficial strengthening effect on mechanical properties of TMCs.

Corrosion Behaviour of TiC-Reinforced Hadfield Manganese Austenitic Steel Matrix In-Situ Composites

The corrosion behaviour of Hadfield manganese austenitic steel matrix composite reinforced with the varying amount of TiC and unreinforced Hadfield manganese austenitic steel matrix alloy has been evaluated in 3.5% NaCl aqueous solution with the pH value of 6 by the potentiodynamic polarization curves and linear polarization resistance measurements at a scan rate of 1 mV/s at room temperature (25°C ± 2°C). The corrosion rate of the composites is higher than that of their unreinforced matrix alloy and it increases with the increasing volume fraction of TiC. The poor corrosion resistance of the composites can be attributed to the galvanic effects between the matrix and reinforcement.

G0400602 放電プラズマ焼結法により作製したTiCまたはTiB強化TiAl合金の機械的特性

Titanium aluminides have some attractive properties such as low density, high strength, high melting point and good creep, corrosion and oxidation resistances at high temperature. So, it is expected as a heat-resistant material and structural material. However, its disadvantage such as low ductility and strength at room temperature make difficult to put to practical use. This work try to improve strength at room temperature by the addition of TiC and TiB as a reinforcement. TiC/TiAl-Nb and TiB/TiAl-Nb composites were fabricated by spark plasma sintering (SPS) process using mixed powders of pure Ti, pure Al and NbC or NbB_2. TiC/TiAl-Nb and TiB/TiAl-Nb composites showed a maximum tensile strength and elongation in TiC volume fraction of 5% and TiB volume fraction of 15%. The Vickers microhardness increased as volume fraction of reinforcement increased. The addition of TiC and TiB led to grain refinement. However, grain growth was observed in the composite with over the Nb atomic mass of 7%.

Effect of Y2O3 on cracking susceptibility of laser-clad Ti-based composites coatings

Ti-based composite coatings reinforced by in situ synthesized TiB and TiC were deposited on Ti6Al4V substrates by laser cladding. The effects of Y2O3 on the microstructure and cracking susceptibility of the coatings were investigated in details. It is shown that a small amount of Y2O3 addition can significantly refine the microstructure of the coatings by hastening spheroidization of the primary phase structure. The maximum refinement in microstructure was obtained with the optimum (2 wt%) addition of Y2O3. Moreover, it can increase the volume fraction of TiC and reduce the residual stress of the coatings due to the decrease in lattice distortion of the α(Ti) matrix. All of these factors lead to the reduction in cracking susceptibility of the coatings containing Y2O3 on the premise that the hardness of the coatings is improved. The fracture toughness of the coatings without and with Y2O3 (2 wt%) is 8.32 and 17.36 MPa·m1/2, respectively. Scanning electron microscope examination reveals a transition of the fractured surfaces from cleavage fracture to quasi-cleavage fracture resulting from the Y2O3 addition.

Conductive TiC/Ti–Cu/C composites fabricated by Ti–Cu alloy reactive infiltration into 3D-printed carbon performs

The microstructure and electrical properties of dense TiC/Ti–Cu/C composites fabricated by pressureless reactive infiltration of Ti–Cu alloy into porous starch-derived carbon preforms prepared by 3D printing was evaluated. Porosities in the range of 65–78 vol% were varied by post-isostatic pressing the as-printed preforms at pressures of 50–400 MPa. The reactive melt infiltration was carried out at 1100℃ in a flowing Ar atmosphere and resulted in formation of a composite comprised predominantly of substoichiometric TiC, binary intermetallic Ti–Cu phases and residual carbon. Scanning electron microscopy analyses revealed a microstructure consisting of dispersed fine-grained TiC in a Ti–Cu matrix surrounded by a continuous carbon phase. Electrical resistivity measurements using the four-probe method were carried out and correlated to the composite microstructure. The electrical resistivity was evaluated in terms of carbon and TiC volume fractions.

Effect of Annealing Temperature on the Precipitation Behavior and Texture Evolution in a Warm-Rolled P-Containing Interstitial-Free High Strength Steel

By using transmission electron microscopy and electron back-scattered diffraction, the effect of annealing temperature on the precipitation behavior and texture evolution in a warm-rolled interstitial-free high strength steel was studied. The results indicated that fine FeTiP could precipitate at 650 °C, and the number of those precipitates increased greatly with the increasing annealing temperature until 800 °C. Furthermore, the nucleation of FeTiP was influenced by the precipitation of TiC and (Ti, Nb) C. The near absence of FeTiP and a large volume fraction of TiC and (Ti, Nb) C in matrix are envisaged to be primarily responsible for the sharp γ-fiber texture. As the boundary pinning effect caused by FeTiP is weak and there are less interstitial C atoms in matrix. Thus, annealing at 800 °C leads to the highest intensity of γ-fiber texture.

Sliding Wear Behavior of Alumina/Tic Coated Steel Produced by Plasma Spray Technique

Carbide coatings exhibit good resistance to wear and has an increased hardness which increases the service life of equipments generally when the surfaces are exposed to critical atmosphere like in thermal power plants. The hard Alumina-Titanium carbide (Al2O3/TiC) carbide coating is developed on the steel by using thermal plasma spray technique. The composition of Al and TiC are varied in the ratio of 70/30, 65/35 and 60/40. Coated samples are analyzed using optical microscope, hardness test, sliding wear and corrosion test. Hard-faced samples are shows uniform distribution of Al2O3/TiC particles on the surface of steel. Surface hardness increases with increasing volume fraction of TiC. The coating of Al2O3/TiC with volume fraction of 30% TiC shows good corrosive resistance compared to other two coating specimens and coating with 40% of TiC has shows good wear resistance than the other two coatings.

Effect of Y2O3 on the sliding wear resistance of TiB/TiC-reinforced composite coatings fabricated by laser cladding

TiB/TiC-reinforced titanium matrix composite coatings were prepared by laser cladding on Ti6Al4V substrates. The effects of the addition of Y2O3 on the microstructure, microhardness, fracture toughness, and dry sliding wear resistance of the coatings were investigated. Microstructural observation showed that the coatings mainly consisted of TiC and TiB particles uniformly dispersed in the coarse cellular dendrites and interdendritic eutectic structure. The addition of Y2O3 refined the structure of the primary phase, improved the microstructural uniformity, and increased the volume fraction of TiC. The average microhardness of the coatings was improved from HV 725.30 to HV 812.98, and the average fracture toughness was increased from 8.32MPam1/2 to 17.36MPam1/2. The coating with Y2O3 had excellent resistance to micro-cutting and cracking. Analyses of the initial worn surfaces showed that the coating with Y2O3 was covered with a thin tribolayer, which consisted of Fe and its oxides. The true worn surfaces of the coating with Y2O3 were smoother than that of the coating without Y2O3 due to the protection by the tribolayer. Analyses of the cross-sections from the wear tracks revealed that the surface of the coating without Y2O3 was covered with many fine cracks which caused the debonding of the fragments from the surface of the coating. The wear mechanism of the coating with Y2O3 was defined as oxidative wear. Measurement results of the worn mass loss and friction coefficient values further verified the positive effect of Y2O3 on the improvement of wear resistance.

Feasible process for producing in situ Al/TiC composites by combustion reaction in an Al melt

In situ Al/TiC composites with a homogeneous distribution of TiC reinforcements were prepared by adding a reactant mixture of Al-Ti-C to an Al melt. A certain amount of CuO addition facilitates a combustion reaction of the Al-Ti-C system and thereby enables the formation of in situ TiC at a reasonably low temperature range of 750–920 °C. Synthesised TiC particles with sizes of 1–2 μm are present in the Al matrix along with Al3Ti. Besides the CuO addition, the melt temperature plays a significant role in the final microstructure of the composites. Increase in the melt temperature up to 920 °C with CuO provides more external heat input and initiates the combustion reaction within a few seconds. Pellet microstructure evidently shows that the polygonal Al3Ti originates from the unreacted layer of which the distance is significantly shortens by increasing the melt temperature. The suppression of the Al3Ti formation is the most likely to occur at 920 °C, with producing a large volume fraction of TiC in situ synthesised.

Enhanced densification of Ti-6Al-4V/TiC powder blends by transformation mismatch plasticity

Abstract

Microstructure and Interface of TiC <i>In Situ</i> Synthesized Reinforced Steel-Based Surface Composite Prepared by V-EPC Infiltrating Method

In order to optimize the processing parameters of TiC/steel composite materials, in-situ TiC particle reinforced steel-based surface composites were prepared by vacuum evaporative pattern casting (V-EPC) infiltration process, and the structure and interface of the composites were investigated. The results show that, TiC particle size with Ti-C-20wt%Fe reaction system was much smaller than the composite with Ti-C reaction system in the same location of the composites. In the composites, the TiC particle size and volume fraction increased and spherical degree dropped from the tradition layers (interface between the substrate and the composite layer) to the outer surface. But the increase of TiC particle size (1-3μm) and volume fractions (25.8%-43.5%) in the composite with Ti-C-20wt%Fe reaction system was obviously lower than that of TiC particle size (1-10μm) and volume fractions (12.3%- 67.7%) in the composite with Ti-C reaction system. The bond zone between TiC particles and the matrices was totally metallurgical bonding without apparent interface. Comparing with the composite with Ti-C-xFe reaction system, the tradition layer with Ti-C reaction system has a poorer internal quality. The forming process of TiC in situ synthesized reinforced steel substrate surface composites prepared by V-EPC infiltrating process was infiltrating of the melting and carbothermal reactions of C and Ti powder the result of joint action.

Improving the Tribological Properties of Mg Based AZ31 Alloy Using Friction Stir Processing

Materials with improved tribological properties have become the pre-requisite of advanced engineering design. Surface metal matrix composites (SMMCs) exhibit a unified combination of good tribological properties and high toughness of the interior bulk metal when compared with monolithic materials. Friction stir processing, a microstructure modification technique, has emerged as one of the processes used for fabrication of SMMCs. Commercial cast or wrought type Mg–Al–Zn AZ-series alloys, such as AZ91, AZ61 or AZ31 with 3–9 wt.% Al and 1 wt.% Zn, have been widely used in automobiles or electronic appliances. Due to low percentage of alloying elements/second phase elements in these alloys, the grain refinement and hence the mechanical properties such as hardness cannot be appreciably enhanced. In this study, FSP was used to fabricate AZ31 based nanocomposite using TiC as reinforcement. FSP was performed at a fixed volume fraction of TiC under varying cooling conditions. Tribological performance of the fabricated composite was investigated using pin-on-disc wear test arrangement. The analysis of the wear surfaces as well as wear debris analysis was done using SEM equipped with EDS. The fabricated composite was found to exhibit superior wear resistance.

Effects of Y addition on microstructure and mechanical properties of TiC/Ti6Al4V composites

TiC/Ti6Al4V composites with different addition contents of Y element were fabricated successfully, and the effects of Y content on the microstructure and mechanical properties of the composites were investigated. The results show that the effects of Y can be considered into two ranges, the one is 0.1–0.5 wt.% and the other 1.0–2.0 wt.%. When the Y addition was in the first range, the morphology of the primary TiC in the composites was dendrite. With the increasing of Y content, eutectic TiC with flake shape or palpus shape began to separate out around the primary TiC and some indexes about microstructure and properties increased including the volume fraction of TiC, the hardness and the compressive strength of composites, while other indexes reduced obviously such as the primary dendrite arm-diameter, the secondary dendrite arm spacing and the abrasive property; On the other hand, when the Y content further increased from 1.0 to 2.0 wt.%, the refinement of dendritic TiC was not obviously. Meanwhile, the hardness and the compressive strength decreased, but abrasive property increased. The hardness and the compressive strength of composites reached the peak value at 0.5 wt.%Y. The refinement mechanism of Y was attributed to the combined effects of the increase in nucleation rate at the constitutional undercooling zone in front of the solid–liquid interface and the reduction in growth rate of TiC.