Volume Fraction Of TiC Research Articles

Enhancing mechanical properties in Ti-Containing FeMn40Co10Cr10C0.5 High-Entropy alloy through Chi (χ) phase dissolution and precipitation hardening

This research investigates the effects of adding 2 at.% Ti on the microstructure, phase transformation, and mechanical properties of FeMn40Co10Cr10C0.5 high-entropy alloy (HEA) in both as-cast and homogenized conditions. The incorporation of Ti increased the lattice parameter of the FCC matrix and caused greater lattice distortion (∼5.9 %) due to the larger atomic radius of Ti. The negative mixing enthalpy of Ti resulted in segregation at interdendritic regions, forming a Ti-rich Chi (χ) phase during solidification. The as-cast structure displayed a dendritic microstructure consisting of 77.9 % FCC, 20.6 % χ, and 1.5 % TiC phases. After homogenization at 1200 °C for 2 h, the χ phase was dissolved, increasing the volume fraction of TiC to 24 %. The homogenized sample exhibited a substantial improvement in tensile properties, i.e., with the ultimate tensile strength (UTS) rising from 631 MPa in the as-cast condition to 689 MPa, and yield strength (YS) increasing from 346 MPa to 419 MPa, while maintaining an elongation of ∼ 54 %. These enhancements are attributed to solid solution strengthening, increased carbide precipitation, and the dissolution of the χ phase into the FCC matrix.

The effect of low-energy high-current pulsed electron beam irradiation on the structure, phase composition and mechanical properties of Ni3Al and Ni3Al-TiC composites

Using scanning and transmission electron microscopy, X-ray diffraction, indentation and bending tests we studied the evolution of microstructure, phase composition and mechanical properties of TiC-free Ni3Al and Ni3Al-TiC composites (TiC content was 10 and 30 vol%) fabricated by self-propagating high-temperature synthesis (SHS) under pressure induced by low-energy high-current pulsed electron beam (LEHCEB) irradiation with the surface energy density of 8, 12 and 18 J/cm2. It was found that the irradiation results in the improvement of phase composition of the near-surface layer by way of the increase of yield of SHS reaction. LEHCEB irradiation enables formation of nanocomposite structure in the near-surface layer of Ni3Al-TiC composites with decreased grain size of Ni3Al matrix, refined TiC particles and increased volume fraction of TiC. This structure leads to the increase of microhardness but decrease of strength under bending. Two mechanisms of TiC particles refining are suggested. The effect of surface energy density on the manifestation degree of the found phenomena is discussed. The contribution of different hardening mechanisms to the overall hardening is considered.

Biomimetic micro-laminated structure endows cermet with excellent strength and toughness using CoCrCuFeNi as infiltration layers

Biomimetic micro-laminated structures are gaining traction for their potential to enhance the mechanical properties of composites. A salient challenge lies in fabricating this intricate layered construct with good interfacial adhesion. In this research, we developed a micro-laminated metal/ceramic composite utilizing CoCrCuFeNi as the infiltration layers. However, after CoCrCuFeNi infiltration, the metal layer phase of cermet transforms into FCC + BCC, which belongs to the category of medium entropy alloy. The mechanical properties displayed a direct relationship with the TiC skeleton's content. Notably, cermet with a TiC volume fraction of 65% exhibited bending strength of 770 MPa, crack-initiation toughness (KIC) of 10.31 MPa•m1/2, crack-propagation toughness (KJC) of 35.1 MPa•m1/2. Mechanisms such as crack deflection and branching acted at the crack tip, significantly reducing peak stress. Contrasting prior studies marked by pronounced interface delamination, the robust adhesion between CoCrCuFeNi and TiC in this study facilitated the congruence of strength and toughness. Our findings introduce a pioneering methodology for designing laminated metal/ceramic composites with CoCrCuFeNi infiltration layers, aiming to achieve superior strength and toughness.

TiC–Fe gradient coating with high hardness and interfacial adhesion strength on cast iron prepared by in-situ solid-phase diffusion method

The improvement of comprehensive properties including hardness, toughness, wear, and adhesion strength of the coating-substrate system, especially avoiding the trade-off between the hardness and adhesion strength, is strongly required for various applications. Herein, an effective strategy is proposed, by in-situ solid-phase diffusion method, to fabricate a novel TiC–Fe gradient coating with high hardness and interfacial adhesion strength on cast iron. The eveloped coating was composed of equiaxed TiC particles and α-Fe phase. The microstructure was graded in TiC size and volume fraction. The formation of the graded microstructure was attributed to the nucleation-growth process controlled by diffusion of the carbon concentration gradient. The TiC volume fraction in the coating was as high as 95%. The phase interface (TiC/TiC interface and TiC/α-Fe interface) and the coating/substrate interface exhibited excellent interfacial bonding at the atomic scale. The novel gradient coating could simultaneously achieve high hardness (23.9 ± 1.3 GPa), high elastic modulus (265.7 ± 9.4 GPa), and excellent adhesion strength (>225 ± 10 MPa). Apparently, in-situ solid-phase diffusion method may provide a new route to fabricate TiC–Fe gradient coatings with high-volume fraction on steel/iron, capable of capable of exhibiting elevated hardness, high elastic modulus, excellent interfacial adhesion strength, and superior wear resistance.

TiC–Fe gradient coating on pure titanium fabricated by in-situ solid-phase diffusion: toward superior hardness and interfacial adhesion strength

Protective hard coatings can significantly improve the bottleneck problem of low hardness and poor wear resistance on titanium alloy surface. However, hardness and adhesive strength usually exhibit an inverse relationship, which greatly limits its widespread use. In this work, TiC–Fe gradient coating with high hardness and adhesion was successfully fabricated by in-situ solid-phase diffusion method (ISDM) on pure titanium at 1000 °C for 2 h. The average thickness of the coating was approximately 5 μm, and the volume fraction of TiC in the coating was greater than 95 vol%. The grain size of TiC gradually increased from 200 nm at the coating surface to 2 μm towards the substrate. The phase interface and the coating/substrate interface exhibited excellent interfacial bonding at the atomic scale. The novel TiC–Fe gradient coating can simultaneously achieve superior hardness (42.9 ± 2.6 GPa) and elastic modulus (557.4 ± 10.3 GPa) that is mainly dominated by in situ synthesised high volume fraction TiC, as well as high adhesion strength (>225 ± 10 MPa). The increased adhesion strength was attributed to the excellent macro/micro interfaces and gradient transition of the microstructure. The use of ISDM to fabricate TiC–Fe gradient coating on titanium alloy may provide a new strategy to improve the comprehensive properties including hardness, elastic modulus, interfacial adhesion strength, and wear resistance for wider applications.

Oxidation behaviour of a MoSiBTiC alloy coated by a (Si+B) co-deposition pack cementation method

A MoSiB based coating was applied to the 1st-generation MoSiBTiC alloy using pack cementation process. After conditioning at 1300 °C for 10 h in air, the coating developed into four layers: an oxide layer, a MoSi2 layer with Mo5Si3 and MoB precipitates, a Mo5Si3 layer, and a MoB+Mo5SiB2 (T2) layer. However, visible holes often formed in the coating due to defects, and the oxidation proceeded to the substrate during subsequent cyclic oxidation. In a controlled test on a MoSiBTiC alloy with lower TiC volume fraction, an intact coating formed after the conditioning at 1300 °C and provided an effective oxidation resistance.

Investigation into Corrosive Wear of the CoCrFeNiTax Laser-Clad Coatings on TC4 in the Neutral and Alkaline Circumstance

CoCrFeNiTax (x = 0, 1) coatings were prepared on the surface of TC4 by laser-cladding to improve the corrosive wear property of TC4 and extend its service life in corrosive media, ultimately aiming to improve its surface performance. The effects of Ta addition on the phase constituent and microstructure of the coatings were first investigated. Given the wide application of TC4 in corrosive media (even undergoing friction), the corrosive wear of TC4 covered with the coatings was especially focused in two media (neutral and alkaline). The results showed that the coatings were composed of primary α(Ti) and eutecticum (α(Ti) + Ti2Ni) as the matrix and TiC as the reinforcement. The introduction of Ta increased the volume fraction of eutecticum and TiC and made the microstructure more uniform. The coating with Ta performed more outstanding corrosive wear resistance than the other two samples in the two media. The wear rate of the coating with Ta was 4.7458 × 10−4 mm3·N−1·m−1 in the neutral environment and 6.6808 × 10−4 mm3·N−1·m−1 in the alkaline environment, 64.45% and 61.79% lower than those of TC4, respectively. The wear mechanism of the samples is a combination of serious micro-cutting, active dissolution, and oxidation, and the introduction of Ta effectively improved the resistance to micro-cutting.

Evaluation of in-situ synthesised titania-zirconia-boron carbide composite cladding on Ti6Al4V substrate using continuous wave fibre laser

In this work, titanium metal matrix composite (TiC, TiB2, TiO2, ZrB2) cladding was synthesised by irradiating a fibre laser beam on a mixture of Ti6Al4V alloy, ZrO2, B4C powders pre-placed on Ti6Al4V alloy plate. The effect of varying wt.% of B4C on the microstructure, hardness, erosion, and wear properties of the composite cladding were investigated using XRD, XPS, EBSD, FESEM with EDAX, nano-indentation, and wear tests. Under the exposure of fibre laser on a mixture of preplaced powders, the in-situ formation of TiC, TiB2, TiO2, and ZrB2 ceramic particles have taken place and get uniformly dispersed in the molten titanium alloy matrix. The volume fraction of these phases increases with the increasing percentage of B4C. A black willow-shaped structure (TiB2) is observed in sample BM3 (30 wt% of B4C), along with grey cellular dendrites (TiC) dispersed uniformly in the matrix. The average microhardness of the claddings increases with the increase of B4C contents. The average weight loss of the cladding samples in dry sliding wear tests decreases with increasing the B4C content. The maximum microhardness of 1582.4HV300 is recorded in BM3 cladding, which is almost four times higher than the substrate material. The decrease in the average value of maximum nano-indentation depth with an increase in the content of B4C is in good agreement with the results of microhardness tests. The hardening of the cladding is also accompanied by increased values of parameters H/E (hardness(H)/Young's modulus (E)) and H3/E2(0.133), indicating better resistance to crack formation during indentation even at higher loads showing the cladding is hard as well as tough. The grain size variation and volume fraction of TiC–TiB2 obtained from electron backscatter diffraction test results agrees with cladding having these properties. The coefficient of friction (0.15–0.25) is found to be lower than the substrate material (∼0.3). The claddings also show good erosion resistance at ambient, 250 °C, 350 °C and 750 °C.

Microstructure and mechanical properties of lightweight (AlNbTiVCr)100-C high entropy alloys by carbide strengthening

• A new type of lightweight (AlNbTiVCr) 100- x C x high entropy alloy were investigated. • The HEAs have BCC Structure and the second phase due to the introduction of carbon. • HEAs exhibit good specific strength and room temperature excellent plasticity. To improve the mechanical properties and decrease the alloy density of AlNbTiVCr high entropy alloy (HEA), (AlNbTiVCr) 100- x C x ( x =0-3.5 at.%) HEAs were prepared, the effect of alloying element Carbon on the microstructure and mechanical properties of HEAs were studied. With the addition of carbon, Laves phase rich in (Cr, Nb) and second phase (TiC) gradually appear in the alloys, and the volume fraction of TiC increases with the increase of carbon content. The addition of carbon significantly improves the strength and plasticity of the alloys. When x =1.5 at.%, the compressive strength and fracture strain reach their maximum values (2.03 GPa and 13%). With the further increase of carbon content, a large number of second phases are formed and aggregated, which worsens the mechanical properties of the alloy. The significant improvement of mechanical properties is attributed to the combination of second phase strengthening and solid solution strengthening.

The Erosion–Corrosion Behavior of Eutectic High Chromium Cast Irons Reinforced by TiC Particles

In this work, high chromium cast irons (HCCIs) reinforced by TiC particles are designed and fabricated to improve the erosion–corrosion and wear resistances of materials for the pumping and handling applications. The TiC particles are formed by the in situ solidification method. The experimental results show that the hardness of as-cast HCCIs is improved significantly with TiC volume fraction. It can be as high as 63 HRC when the TiC volume fraction is 9.8%. The introduction of TiC increases the abrasive wear resistance of the HCCIs in both as-cast and heat-treated states. However, it is unexpected to find that the presence of TiC significantly reduces the erosion–corrosion performance. It suggests that corrosion-enhanced erosion is the dominant mechanism that controls the mass loss of the TiC-strengthened HCCIs.

Abrasive wear behavior of TiC-strengthened eutectic high chromium cast iron composites

The present research on high chromium cast irons (HCCIs) strengthened with TiC particles was motivated by a need to improve the abrasive wear resistance of materials for mining equipment such as board hammers and liners. The effect of TiC content and heat treatment on the wear properties of eutectic HCCIs was investigated by combining the three-body abrasive wear and micro-scratch tests. The experimental results show that the wear rate of the as-cast HCCIs decreases from 8.0 to 5.1 cm3/cm·10−8 as the volume fraction of TiC increases to 9.8%. The superior wear resistance of TiC-reinforced HCCIs was originated from the synergic contributions of ductile austenitic matrix and high volume fraction of carbides. However, the heat treatment reduces the hardness and wear resistance of the HCCIs with high TiC content due to the high volume fraction of brittle carbide phases and the low ductility of martensite matrix.

In-situ TiC particles strengthen and ductilize Fe1.2MnNi0.8Cr high entropy alloy

In-situTiC particles reinforced Fe1.2MnNi0.8Cr high-entropy alloy matrix composites (HEACs) were prepared by vacuum induction melting. The effects of Ti and C additions on the microstructural evolution and mechanical properties of the new composites were investigated. It was found that by adding Ti and C, not only were TiC particles produced in situ, extra solid-solution effect was also introduced to strengthen the HEA matrix. As the volume fraction of TiC increased, both the ultimate tensile strength and the percent elongation of the composites first increased then decreased while the hardness increased and remained high. The ultimate tensile strength of the composites was found to reach 856 MPa when the content of TiC was 5.9 vol %, which is 30% greater than that of the HEA base. At the same time, the percent elongation was found to be 34%, an increase by 42% as compared to the HEA matrix. Due to the combined effects of Orowan mechanism, load transfer and solid solution strengthening, the new composites have achieved an unity of high tensile strength and good plasticity.

Microstructures and properties of Ti/TiC composites fabricated by laser-directed energy deposition

Titanium/Titanium Carbide (Ti/TiC) composites with 20, 40 and 60 vol% of TiC powders were deposited on Ti-6Al-4V substrates using a laser-directed energy deposition method. The bulk relative densities exceeding 99% were achieved in the deposits. The evolution of microstructures and local chemical compositions in the deposits under rapid melting and solidification were analyzed using X-ray diffraction, electron probe micro-analyzer and scanning electron microscopy. Assessment of mechanical integrity of the deposits involved microhardness, tensile testing and fractography. The deposition process resulted in defect-free deposits with 20% TiC. However, cracks were observed originating from the substrate/deposit interface in the 40% and 60% TiC deposit. The L -DED process caused only partial dissolution of the initial TiC particles and the amount of undissolved particles in the deposited matrix increased with increasing TiC volume fraction in the initial powder feedstock mixture. A non-stoichiometric TiC 0.55 compound was found to form during solidification. The solidified product in the deposits included dendritic and equiaxed TiC 0.55 precipitates homogeneously distributed in the matrix. Micro-hardness measurements indicated that hardness values increased monotonically with TiC content in the deposit. On the other hand, a gradient Ti/TiC composite with composition ranging between 20% and 60% TiC did not develop any growth cracks suggesting an efficient processing route for synthesizing MMCs with high volume fraction of brittle ceramic reinforcements. It was found that pre-existing cracks in the TiC used in the starting feedstock played a key role in the mechanical integrity of the deposits. This observation suggests that the mechanical performance of the Ti/TiC composite deposits can be improved using techniques that promote complete dissolution of the original TiC.

Hybrid processing of TiC/TiCu/C composites with tailored hardness

This work reports the effect of TiC volume fractions on hardness of TiC/TiCu/C composites synthesized through in situ reactive infiltration of Ti-Cu alloy into porous carbon preforms prepared by 3 D-printing. Reactive melt infiltration of the alloy at 1100 °C under argon into C-preforms with different porosities resulted in materials composed of TiC, Cu-rich intermetallic matrix (Ti3Cu4) and residual carbon. The microstructure consists of TiC grains distributed along the Cu-Ti/C boundary. The hardness of TiC/Ti3Cu4/C composites could be tailored by the TiC volume fraction and the distribution in the composites, which are determined by the processing parameters and the initial porosity of the carbon templates in 3 D-printing stage. The hardness of the produced composites ranges from 350 HV to 570 HV and could be tailored by the TiC volume fraction and distribution in the composites, which are determined by the processing parameters and the initial porosity of the carbon-preforms.

Analysis of precipitation characteristics of TiC at different quenching and partitioning temperatures and its effect on the mechanical properties

Intercritical annealing, quenching and partitioning (I&QP) steel is the most promising one of the third generation advanced high-strength steel. However, iron carbides are inevitable in I&QP steel. They can consume the carbon partitioning from supersaturated martensite to austenite and thus reduce the stability of austenite. Furthermore, the transition iron carbides, i.e., ε and η, are harmful to the toughness and ductility. In this work, the addition of Ti has been proved to effectively suppress the formation of the transition iron carbides. The precipitation characteristics of TiC at different quenching and partitioning temperatures (QT and PT) was investigated mainly by transmission electron microscopy, small angle neutron scattering and three-dimensional atom probe tomography techniques. The results showed that more carbides precipitated at the PT of 450 °C compared with that of 400 °C, and the volume fraction of TiC decreased with the increase of QT at the PT of 450 °C, which are mainly determined by the precipitation kinetics and initial martensite fraction. The nano-sized TiC particles are formed at the dislocations within the martensite and austenite and the interface between the two phases, indicating that the high dislocation density can promote the precipitation of TiC. However, the precipitation of TiC decreases the carbon content of retained austenite and thus affects its stability; moreover, the formation of TiC consumes the carbon atoms pinning the dislocations and thus has an important effect on the yield strength and yield platform. This work is essential for suppressing the formation of transition iron carbides, understanding the precipitation characteristics of TiC and designing the I&QP steel with improved mechanical properties.

Microstructure and mechanical properties of in-situ TiC reinforced FeCoNiCu2.0 high entropy alloy matrix composites

FeCoNiCu2.0 high entropy alloy matrix composites reinforced with different TiC volume fraction (0 vol%, 5 vol% and 10 vol%) were prepared by induction melting. The reaction mechanism in TiC/FeCoNiCu2.0 HEA was studied by thermodynamic analysis and the microstructure of the composites was observed to study the effect of different volume fraction of TiC reinforcement on the mechanical properties of the composites. The results show that all the composites matrix was a solid solution of FCC phase. The reaction mechanism of Ti–C–Cu revealed the formation process of TiC in the HEAs. With the increase of the volume fraction of TiC, the number and size of TiC particles increase and the morphology becomes more uniform. When the volume fraction of TiC reached 10 vol%, the composite has the optimal ultimate tensile strength of 698 MPa, which is 47.6% higher than that of the matrix.

Effects of TiC addition on microstructure, microhardness and wear resistance of 18Ni300 maraging steel by direct laser deposition

18Ni300 maraging steel with different TiC contents (0−10 wt.%), for the first time, have been fabricated by a direct laser deposition (DLD) technique. The microstructure and properties of the as-deposited and heat-treated samples have been carefully investigated. The obtained results show that the original 18Ni300 maraging steel exhibits extremely fine cellular microstructure with an average diameter of 3.7 μm, composed of martensite (M) and Ti2N. In contrast, the microstructure of the TiC-reinforced composites is significantly refined, in which the volume fraction of TiC formed with different morphologies varies with the TiC addition content. However, some cracks exist in the composite sample with the TiC addition up to 10 wt.%. The average microhardness of the as-deposited samples increases initially and then decreases with increasing TiC content, and the maximum microhardness (444 HV0.2) is obtained after adding 5 wt.% TiC. In addition, the sample with 5 wt.% TiC has been experienced a solution treatment at 850 ℃ for 1 h and then a subsequent aging treatment at 500 ℃ for 3 h. A number of nano-precipitates Ni3(Mo,Ti) and a few austenite are formed, which are dispersed in the martensite matrix after the heat treatment. This results in a high microhardness of 576 HV0.2 and a low wear rate of 1.37 × 10-6 mm3/(N·m), compared with those of the TiC-free sample (368 HV0.2 and 5.61 × 10-5 mm3/(N·m)), respectively. The possible microstructural mechanisms accounting for the property changes of the TiC-reinforced 18Ni300 maraging steel have been discussed in detail.

High-temperature oxidation behavior of TiC and TiC + TiB reinforced TB8 matrix composites prepared by spark plasma sintering

TB8 (Ti-13.58Mo-2.15Nb-3.27A1-0.21Si) is a metastable β titanium alloy with excellent mechanical properties. In this paper, TiC/TB8 and TiC + TiB/TB8 titanium matrix composites (TMCs) were prepared by spark plasma sintering (SPS). In addition, the cyclic oxidation interval measurement method was used to compare the high-temperature oxidation behavior of TB8 titanium alloys with different volume fractions of TiC and TiC + TiB reinforced TB8 composites. Studies have shown that after cyclic oxidation at 800 °C for 100 h, the oxidation law of TB8 is a mixture of linear and parabolic, while TMC1 (2.5 vol.% TiC), TMC3 (5 vol.% TiC) and TMC4 (3.5 vol.% TiC + 3.5 vol.% TiB) oxidation mainly follows the parabolic law. Moreover, the oxidation weight gain of TB8 after oxidation is as high as 9.83 mg/cm2, while the oxidation weight gain of TMC1, TMC3 and TMC4 is only 5.95 mg/cm2, 6.81 mg/cm2 and 2.83 mg/cm2. It shows that during the entire oxidation process, the order of excellent high-temperature oxidation resistance is TMC4 > TMC1 > TMC3 > TB8.

Characterization of aluminium AC4B/Nano TiC composite with the variation of volume fraction of nano TiC reinforced through stir casting process

Characterization of aluminium ac4b/nano tic composite with variation of volume fraction of nano TiC reinforced through stir casting process has been studied. The aluminium matrix used was aluminium alloy AC4B, which contain silicon and copper as its main alloy. Furthermore, the addition of Nano TiC into AC4B composite can increase the tensile strength, ductility, and toughness of AC4B composite by refining the dendrite structure of the α-Al phase and forming super saturated solid phase, θ (Al2Cu). In this study, AC4B/Nano TiC composite were made through stir casting with some variable parameters of Nano TiC reinforce composition of 0.25%, 0.3%, 0.35%, 0.4%, and 0.5% volume fraction to determine the optimum value of the mechanical properties of AC4B/Nano TiC composite. Stir casting process was chosen because it has several advantages, such as easy to use, flexible, and can be used to produce a large number of the products. It is known that AC4B/Nano TiC composite has optimum value of the mechanical properties when Nano TiC composition is 0,3% volume fraction with ultimate tensile strength of 132,31 MPa and the hardness of 55,18 HRB.

Synergistic strengthening of FeCrNiCo high entropy alloys via micro-TiC and nano-SiC particles

Adding reinforcing phases is an effective method to improve the mechanical performance of high entropy alloys. The strengthening effect of single reinforcement type has thus been studied to a great extend. Here FeCrCoNi high entropy alloy matrix composites embedded with micro-scale TiC and nano-scale SiC particles were fabricated via vacuum inductive melting method. The combined volume fraction of TiC and SiC particles was 10%, while the volume fraction of each particle was varied namely, 10 : 0, 7: 3, 5 : 5, 3 :7, and 0 : 10. The results show that the composite matrix has FCC structure, and the micro- TiC and nano- SiC particles were developed in the matrix through in-situ reactions. When the volume ratio of TiC and SiC particles is 7: 3, the mechanical properties reach the optimal combination. The yield tensile strength of the composite is 498.0 MPa, which is 207.2% higher than that of the matrix. The percent elongation is 41.2%. The strength increase stems from a synergy of grain refinement, thermal mismatch, solid solution, load bearing effect, and Orowan effect.