TiC Reaction Research Articles

Effects of Cu, Sn, and Ti doping on the interfacial properties of Ag-based filler metal/WC: First-principles study and experimental characterization

First-principles calculations were used to determine the formation energy, work of adhesion, and electronic structure of the interface of Ag-doped (Cu, Sn, and Ti)/WC, revealing the effect of doping atoms on the interfacial bonding behavior. Additionally, an active filler metal Ag–Cu–Sn–Ti was developed from the calculation results and applied to braze YG18 cemented carbide/40Cr steel joint. The interfacial structure and elemental diffusion behavior at the filler metal/WC interface were characterized. The doping of Cu and Ti at the interface contributes significantly to the stability of the interfacial structure and the improvement of the work of adhesion. The effect of doping of Sn atoms at different positions on interfacial stability and the work of adhesion is not obvious, and it can be doped into Ag alloys as a melting point depressant. The charge accumulation zone and atomic orbital hybridizations at the interface contributes to enhance the interface stability and the work of adhesion. The TEM analysis demonstrates that the diffusion behavior of Ti is particularly noticeable, aggregating at the Ag/WC interface and interacting with C to generate a TiC reaction layer, ultimately producing a WC/TiC/Ag interface structure.

Brazing of graphite to tungsten using graphene nanoplates reinforced TiNiCu composite filler

Graphene nanoplates (GNPs) reinforced TiNiCu composite filler (TiNiCuG) developed with which the brazing of graphite to W was achieved in this study. The effects of the GNPs reinforcement and brazing temperature (1120–1200 °C) on the interfacial microstructure and mechanical properties of brazed joints were implemented in detail. Experimental results revealed that the bonding of graphite and filler material was achieved through the formation of a TiC reaction layer. A well bonded TiC/Ti(Ni,Cu) interface with lattice mismatch of 6.8% was observed by HRTEM. The FCC TiC and monoclinic Ti(Ni,Cu) taken the coherent orientation relations of [01̅1]fcc║[331]. The typical interfacial microstructure of graphite/W joint using TiNiCuG at 1180 °C for 15 min was graphite/Ti(Ni,Cu)+ Ti2(Ni,Cu)+TiC /W(Ti)ss/W. The added GNPs reacted with Ti and in-situ synthesized TiC particles by reducing the residual stress to strengthen the brazed joint and increase the thickness of the brazing seam. The shear strength of the joint using composite filler reached the maximum value of 37.59 MPa, 132% higher than that joint without using GNPs.

Microstructure and properties of a YG18/40Cr joint vacuum–brazed by Cu–Sn–Ti filler metal

In this study, dissimilar YG18/40Cr joints were prepared using a Cu–Sn–Ti filled metal by a vacuum brazing process, and the microstructural evolution and bonding mechanism of the YG18/Cu–Sn–Ti/40Cr joints were studied. By adjusting the brazing parameters, the formation process of interface structure, the joint structure and matrix internal structure, and the changes in the joint microstructure and properties under different parameters were systematically analyzed. A TiC reaction layer was formed at the interface on both sides of the joint. The brazing performance can be improved by the formation of a reasonable size reaction layer. A TiC–WC cemented carbide was formed near the middle layer inside YG18, and this tenon–and–tenon structure improved the bonding between the YG18 side and the filler alloy. The connector structure was YG18/TiC/CoTi + Co2SnTi/Cu [s, s]/eutectic structure (Cu [s, s] + Cu Sn3Ti5)/CuSn3Ti5/TiC/40Cr, and its eutectic structure changed as the parameters changed. The maximum average shear strength of the YG18/40Cr joint brazed at 940 °C for 5 min reached 216 MPa, which was ≈25% higher than the joint shear strength of the pure copper used in a previous study. The fracture morphology of the joint showed a large number of fossae and tear edges, indicating ductile fracture.

Microstructure and mechanical properties of single-crystal diamond/Kovar alloy joints brazed with an AgCuTi metal filler

Joining single-crystal diamond with the Kovar alloy has great application potential in the field of optoelectronic devices. In this work, single-crystal diamond was brazed with a Kovar alloy by using an AgCuTi metal filler at a temperature of 830 °C with a dwell time of 5 min. The corresponding microstructures and interfacial products of the brazed joints were systematically studied. AgCuTi interacts with diamond, and a continuous TiC reaction layer with a thickness of 0.5–1 μm forms at the interface between diamond and the residual AgCuTi metal filler. In contrast, there is no obvious reaction layer at the interface between the Kovar alloy and the residual metal filler; however, it is observed that the metal filler penetrates the Kovar alloy along the grain boundary of the Kovar alloy. In addition, the compression shear strength of the brazed joint was tested, and the fracture morphologies were analysed. The maximum shear strength of the brazed joint is 102.73 MPa, and the fracture shows mixed ductile and brittle characteristics.

The influence of interface structure on the microstructure and properties of Cu/graphite joint prepared by vacuum diffusion bonding

The hybrid structure of copper and graphite has important applications in plasma-oriented components and automobile commutators. In view of the poor wettability of copper to graphite and the large residual stress of the joint, the Cu and TiH2 mixed powder was used as the interlayer and the corrugated interface structure was designed for Cu/graphite vacuum diffusion bonding in this paper. The metallurgical reaction between active element Ti and the matrix on both sides was investigated. It showed that the Ti reacted with C atoms on surface layer of the graphite to form a TiC reaction layer with thickness of 0.5–1 μm, while Ti and Cu formed solid solution and Cu–Ti intermetallic compounds. The Cu/graphite joint consisted of graphite/TiC layer/Ti–Cu intermetallic compound + Cu-based solid solution/Cu. The relief of residual stress benefit by the corrugated interface structure were revealed. The shear strength of the joints with the long wavelengths structure reached 22.9 MPa. The corrugated interface structure can obviously change the distribution of residual stress in the joint, thus effectively improving the bonding strength of the Cu/graphite joint.

Microstructure and properties of WC–Co cemented carbide/40Cr steel joints brazed at low–temperature with Ag–Cu–In–Ti filler alloy

WC–Co cemented carbide/steel brazed at low–temperature is of significant scientific and technical interest. In this study, the interface microstructure between the filler alloy and WC–Co and 40Cr steel, the formation process of the joint microstructure, and the effect of brazing temperature on the microstructure and properties of joints were systematically studied. The filler alloy was bonded by forming a TiC reaction layer with WC–Co and 40Cr steel, which enhanced the retention of the filler layer on the joint. The microstructure of the joint was a WC–Co/TiC reaction layer/TiCo reaction layer/Cu2InTi + eutectic structure (Ag [s, s] + Ag–doped Cu7In3 + Cu4In) + Cu [s, s]/TiC reaction layer/40Cr steel. Moreover, the maximum average shear strength of the joint (brazed at 740 °C) reached 258 MPa, which is approximately 60% higher than those reported in the literature. The fracture behavior of the joint was mainly affected by the distribution of the Cu2InTi intermetallic compounds in the filler layer and the diffusion of Co from the cemented carbide.

Resistance brazing of C/C composites-metallized SnAgCu-Ti powder to T2 copper using AgCuTi filler metal

Carbon/carbon (C/C) composites and T2 copper (Cu) alloy were successfully welded by the following two-step process: the pre-metallization on C/C composites was successfully prepared by the vacuum brazing welding using SnAgCu-xTi(x = 1, 2, 3, 4, and 5 wt%) metal powder and the subsequent reliable C/C composites-Cu joints were obtained by resistance brazing welding with AgCuTi filler metal as the interlayer in this paper. The typical interface morphology of the metallization layer on the surface of C/C composites, microstructure, mechanical properties, and fracture mechanism of resistance brazing welded joints were investigated by the relevant analysis method. The smooth metallization layer was generated on the surface of the C/C composites in the pre-metallization process successfully. The formed excellent bonding between the metallization layer and C/C composites in this stage was prepared for the subsequent welding process. Meanwhile, a strong interfacial bond was obtained due to the formation of the TiC reaction layer in the subsequent resistance brazing welding process. Molten solder infiltrated the pores of the C/C composites and formed a ‘pinning structure’. The residual thermal stress and mismatch of CTE could be relieved by the gradient layer and the shear strength could reach 19.68 MPa.

Microstructure characterization and damping behavior of the novel graphene oxide/TiNi laminate composite sheet

• An innovative graphene oxide/TiNi laminate composite sheet was designed and prepared. • The continuous Ti 2 Ni and TiC reaction layers were generated along the GO/TiNi interface without obvious disjunct. • The composite sheet showed superior damping properties than TiNi alloy and TiNi laminate sheet without GO. In this paper, the interfacial microstructure and damping behavior of the novel graphene oxide/TiNi laminate composite sheet (GO/TiNi) were characterized. Results showed that the well-bonded GO/TiNi interface and alternating laminate structure were obtained in the composite sheet. The continuous reaction layer adjacent to the TiNi matrix was detected as the Ti 2 Ni phase with cubic structure, and the reaction layer near the GO was confirmed as the TiC nanocrystalline. The rhombohedral Ni 4 Ti 3 phase could be tracked to precipitate within the TiNi matrix. Compared with the TiNi alloy and TiNi laminate sheet without GO, the GO/TiNi laminate composite sheet has the optimal intrinsic damping capacities with the tanδ (martensite) of 0.089 and tanδ (austenite) of 0.034, which are attribute to the effective introduction of the high damping GO reinforcement.

The Influence of Carbon Sources on the Microstructures of In Situ-Synthesized TiC in Al Melts.

In this work, graphite and diamond are successfully introduced into Al melts and TiC is in situ-synthesized based on reactive wetting. It is found that the microstructures of the prepared TiC-reinforced Al composites are varied with the change in carbon sources and their sizes. TiC particles tend to form agglomerations in the composites prepared by both graphite and diamond, but the size of the TiC particles as well as their agglomerations will decrease with the decrease in the carbon source size. In addition, the Ti-C reaction is also difficult to fully carry out due to the influence of the Al-C reaction. As a result, in addition to TiC particles, Al4C3 will also be present in the composites prepared by graphite, especially when the size of graphite is large. As for the composites prepared by diamond, diamond@Al4C3@TiC core–shell particles will form when the size of the diamond is large, such as 10 μm in this work, and these particles will transform into Al4C3@TiC core–shell particles when the size of the diamond is decreased.

Design CuZr alloy to control Ti diffusion and reaction layer thickness in C/C-TC4 joins

Brazing C/C composites and Ti6Al4V (TC4) can expand their practical applications, but the too much brittle TiC at C/C side is harmful to joint strength. The key to high-quality brazing joints is to control the excessive diffusion of Ti element from TC4 and TiC reaction layer at C/C. Herein, a new type of CuZr brazing alloy was designed, since Cu element can react with Ti, and Ti element are infinitely miscible in Zr. The interfacial microstructures showed that CuZr alloy reacted with Ti to form Ti 2 Cu + (Zr, Ti) 2 Cu, preventing diffusing Ti and optimizing reaction layer thickness. The effects of brazing temperature and holding time on microstructure changes were analyzed. When the temperature and holding time was insufficient, TiC+ZrC reaction layer was formed not well and inhomogeneous Ti(s, s) and Ti 2 Cu were dispersed in (Zr, Ti) 2 Cu, leading to a relatively low shear strength. Microstructures of continuous TiC+ZrC reaction layer and homogeneous (Zr, Ti) 2 Cu + Ti 2 Cu were optimized as temperature and holding time increased. Optimal microstructure of the joints was brazed at 970 °C for 10 min, which was C/C-TiC+ZrC/Ti 2 Cu + (Zr, Ti) 2 Cu/Ti(s, s)-TC4, and the joint reached the maximum shear strength about 54.2 MPa. • The design of CuZr alloy controls the diffusion of Ti interfacial reaction thickness. • Ti-Cu-Zr reaction phase was revealed by Gibbs free energy analysis method. • The effects of brazing temperature and holding time were investigated in detail. • The shear strength attained to 54.2 MPa by optimizing temperature and holding time.

The microstructures of in-situ synthesized TiC by Ti-CNTs reaction in Cu melts

Abstract In order to study the influence of the carbon nanotubes (CNTs) as a source of carbon on the microstructure of in-situ synthesized TiC in Cu melts, CNTs and Ti powders were introduced into melted Cu to prepare TiC-reinforced Cu matrix composites. The influence of Ti/C ratio and Si on the microstructures and properties of the composites were also examined. It is found that CNTs can be effectively wetted through the Ti-C reaction and successfully introduced into Cu melt to synthesize TiC. In examining the changes in Ti/C ratio, it was found that an increase in the Ti content may result in the decrease of TiC agglomeration and improvement of TiC dispersion, while simultaneously causing an increase in the TiC particle size. Besides, while the addition of Si into Ti-CNTs mixture can also improve the distribution of TiC, the effect is weak compared with that of increasing the content of Ti. It was also found that the highest hardness (238.8 HV) is achieved by the Cu-Ti-C composite with the highest Ti/C ratio, while the electrical conductivities of all the prepared composites are relatively low, which should be due to the insufficient reaction between Ti and CNTs.

Microstructure and Phase Evolution Characteristics of the In Situ Synthesis of TiC-Reinforced AZ91D Magnesium Matrix Composites.

TiC-reinforced AZ91D magnesium alloy composites were synthesized through the in situ reaction between an AZ91D melt and Ti-C-Al preforms. The microstructural evolution characteristics and phase transformation were investigated at different melt reaction temperatures (1013, 1033, and 1053 K), with the aim of understanding the in situ formation mechanism of TiC particles from thermodynamic and kinetic perspectives. The results showed that the temperature played a critical role in determining the formation and morphology of TiC. Initially, only the Al3Ti phase was formed through the reaction between Ti and Al when the temperature was 1013 K. With the increase in the melt temperature, the A13Ti’s thermodynamic stability decreased, and dissolution and precipitation reactions occurred at higher temperatures (1033 and 1053 K, respectively), contributing to the formation of TiC particles. The formation of the TiC phase was attributed to two factors: Firstly, A13Ti as an intermediate product reacted with carbon and formed TiC with increasing temperature. Secondly, the in situ TiC reaction was promoted due to the increased reaction-driving force provided by the increasing temperature.

Effect of holding time on interfacial reaction layer characteristics and mechanical performance of brazed diamonds with Cu-Sn-Ti-Ga filler metals

The diamond joints of the diamond/CuSnTiGa solder system were prepared under the holding time of 3 min, 6 min, 9 min, 12 min, and 15 min, respectively. The effect of brazing holding time on the microscopic morphology, interface characteristics, element distribution changes and mechanical properties of brazing diamond was studied. When the holding time is 6 min, a continuous and uniform TiC reaction layer has been formed at the interface. Etching of diamond and XRD results both proved the formation of TiC. The microhardness results show that when the holding time is 6 min, the maximum hardness at the interface is 318 HV0.1, and the uniformly fluctuating friction coefficient and grinding removal amount are obtained at the holding time of 6 min. Finally, combined with the analysis of the worn surface morphology, the interface reaction of the base brazing filler metal is closely connected, and the filler metal has a high holding force on the diamond. The 6 min heat preservation can effectively improve the bonding strength and wear resistance of the filler metal and the diamond, and meet the expected use requirements.

Inhibiting the interfacial reaction between few-layered graphene and titanium via SiC nanoparticle decoration

The high reaction tendency between graphene and titanium (Ti) matrix during fabrication of graphene/Ti composites aggravates the structural integrity of graphene and limits its outstanding strengthening potential. In order to solve this problem, in this study, few-layered graphene (FLG) decorated with SiC nanoparticles (SiCp@FLG) was synthesized to reinforce Ti-6Al-4V (Ti64) alloy via a powder metallurgy route. Microstructure and Vickers hardness of the developed SiCp@FLG/Ti64 composites were studied systematically. Results showed that the SiCp decoration changed the morphology of FLG/Ti interface from continuous TiC reaction layer to discontinuous TiC nanoparticles during hot-press sintering. This discontinuous interface not only kept the integrity of FLG by suppressing its reaction with Ti matrix but also led to direct bonding between FLG and Ti. This designing strategy of protecting the reinforcement by secondary particle decoration can be potentially applied to the development of high-performance metal matrix composites.

Interfacial microstructure and properties of Al2O3/K-52 austenitic stainless-steel-brazed joints based on the Ni–45Ti filler alloy

In this study, Al 2 O 3 workpieces and K-52 austenitic stainless steel (K-52 ASS) were brazed in vacuum by using the Ni 45Ti filler alloy. The typical interfacial microstructure of Al 2 O 3 /K-52 ASS and K-52 ASS/K-52 ASS joints brazed at 1350 °C for 30 min and the bonding properties of the brazed joints were investigated. The featured interfacial microstructure of Al 2 O 3 /K-52 ASS-brazed joints bonded at 1350 °C for 30 min comprised Al 2 O 3 , TiC layer, Cr 7 C 3 , γ-FeNi (s, s), and austenite matrix phases. The mechanism of Al 2 O 3 /K-52 ASS-brazed joint formation was discussed in detail. The free atoms in K-52 ASS and NiTi solder continuously diffused towards each other during brazing, and then, with the continued brazing reaction, they infinitely dissolved to form a solid solution without a phase interface due to severe mutual diffusion. A TiC reaction layer was formed adjacent to Al 2 O 3 at the joint interface. The joint brazed to K-52 ASS at 1300 °C for 30 min attained the maximum shear strength of 344 MPa, and the brittle fracture of the joint was transformed into a dimple-like ductile fracture at high temperature. The mechanical properties of the Al 2 O 3 /K-52 ASS joint were strongly related to the diffusion zone morphology. We brazed Al 2 O 3 workpieces and K-52 ASS by using the Ni 45Ti filler alloy under vacuum, the typical interfacial of Al 2 O 3 /K-52 ASS brazed-joint bonded at 1350 °C for 30 min comprised of Al 2 O 3 , TiC layer, Cr 7 C 3 , γ-FeNi (s, s), and austenite matrix phases. Strong interdiffusion occurred between K-52 ASS and the Ni 45Ti filler metal during brazing until they completely formed a solid solution without phase interfaces, which resulted in the formation of the TiC reaction layer adjacent to Al 2 O 3 along the liquid–solid interface. • Ni–45Ti (wt.%) filler metal was fabricated to braze Al 2 O 3 workpieces and K-52 ASS under vacuum. • The featured interfacial microstructure of Al 2 O 3 /K-52 ASS joints brazed at 1350 °C for 30 min were investigated. • The mechanism of Al 2 O 3 / K-52 ASS-brazed joint formation was thoroughly discussed. • The fracture morphology of the Al 2 O 3 /K-52 ASS and K-52 ASS/K-52 ASS brazed joints were analysed.

Brazing of graphite and stainless steel with Ag-Cu-Ti filler: Effects of brazing process parameters on microstructure and mechanical properties

Using Ag-Cu-Ti solder (an active filler alloy) system, the graphite and stainless steel substrates were successfully connected by vacuum brazing. The phase composition, microstructure results show the solder is completely melted during the temperature form 850–1000 °C, and part of the Ti has reacted in the matrix. It forms a reaction layer with the graphite layer to form TiC, and a TiFe diffusion layer with the stainless steel layer. The composition of the joint was found to be graphite/TiC/Ag(s,s)+Cu(s,s)+Ag-Cu eutectic/TiFe/stainless steel by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). As the brazing temperature gradually elevated in the range of 850–1000 °C, TiC reaction layer on graphite side and TiFe reaction layer on stainless steel side became thicker. Moreover, brazed joints showed the first increase and later decrease variation trend in terms of their shear strength, which peaked at the temperature of 950 °C. Besides, as holding time extended from 10 to 30 min at 950 °C, the thickened reaction layers of TiC and TiFe were observed, and the joint resistance showed the first increase and later decrease trendwhile. When holding time extended from 30 to 60 min, the holding time made no significant difference to shear strength. The temperature of 950 °C and 10 min holding time were determined as the optimal brazing temperature and holding time, and joints were dense and crack-free with shear strength of about 27.4 MPa and contact resistance of about 42.5 mΩ. It has excellent electrical conductivity while ensuring the high mechanical strength of the connection strength.

TZM/graphite interface behavior in high-temperature brazing by Ti-based brazing filler materials

Graphite was successfully brazed to TZM alloy using the Ti-56Ni, Ti-8.5Si, Ti-33Cr and Ti-30V-3Mo brazing filler materials, respectively, and the corresponding brazing temperatures ranged from 1300 to 1700 °C. The results show that the microstructure of TZM/graphite braze metal was composed of NiTi and Ni3Ti compounds when using Ti-56Ni brazing filler, and the discontinuous TiC compounds were found at the Ti-56Ni/graphite side. When using the Ti-8.5Si, Ti-33Cr and Ti-30V-Mo brazing fillers, the metallurgical combination was obtained due to the formation of the Ti-Mo solid solution at the TZM/brazing filler side and the TiC reaction layer at the graphite/brazing filler side. The fracture was occurred at the interface of TiC/graphite during shear test, which indicated the poorer bonding strength between the graphite and granular TiC.

In-situ TiC reinforced Al-4Cu matrix composite: Processing, microstructure and mechanical properties

Al-4Cu alloy matrix composites reinforced in-situ by TiC particulates were prepared by microwave heating (MH) and conventional heating (CH). The samples were heated up to 1273 K in vacuum induction melting furnace and vacuum microwave heating furnace, respectively. The thermodynamics and dynamics associated with the two systems were discussed and the activation energy related to two heating methods was also calculated. The influence of microwave heating on chemical reaction was analyzed. The results showed that Al reacted with Ti to form TiAl3 and carbon atom then displaced Al in TiAl3 to form TiC. The activation energy of TiC reaction generated by MH and CH were 41.4 kJ/mol and 270.0 kJ/mol, respectively. The ultimate tensile strength increased with the increase of TiC volume fraction. In addition, the ultimate tensile strength of the composite prepared by MH was higher than that of the sample prepared by CH.

Nature-inspired nacre-like Ti6Al4V-(Ti2AlC/TiAl) laminate composites combining appropriate strength and toughness with synergy effects

Nacre, a biomimetic model system with multiscale architectures and adjustable components, has always inspired researchers to create novel materials with advantages such as light-weight, exceptional strength and toughness. Inspired by nature, nacre-like bionic Ti2AlC/TiAl–Ti6Al4V laminated composite sheets had been designed and fabricated by spark plasma sintering technology using commercial Ti6Al4V as the toughening layers and Ti–Al–TiC reaction system as the composite layers. The phase compositions and structural characteristics of the composite sheets were characterized by XRD, SEM and EDS. In addition, the mechanical properties at room temperature were also measured. The results indicated that a Ti3Al interfacial layer was formed between the composite layer and the toughening layer, meanwhile the compositions of the composite layer were composed of TiAl, Ti3Al, Ti2AlC and a small amount of TiC. It's noteworthy that the Ti2AlC/TiAl–Ti6Al4V laminated composite sheets showed a significant increase in toughness while maintaining or improving strength even with holes in the sheets, in comparison with monolithic TiAl. When the loading direction was perpendicular to the laminated structure, the flexural strength and fracture toughness of the composite sheet with 20 wt% Ti2AlC reached good comprehensive values, which were up to 564.86 MPa and 39.15 MPa m1/2, respectively. The particles-reinforced composite layers and laminated structure design not only affected the crack propagation, but also cooperated with each other leading to a complex deflection and expansion behavior, which consumed the fracture energy and improved the overall mechanical properties of the composite sheets.

Interface design of lead-free free-cutting titanium reinforced graphite brass composites and its effect on mechanical properties and cutting performance

Graphite (Gr) is used as a substitute element for lead to avoid environmental pollution and human hazards due to its solid lubrication and chip breaking similar to lead in brass. However, the mechanical properties of brass would be reduced due to non-wetting and weak interfacial bonding between Gr and brass matrix. Based on the preparation of graphite brass composites by powder metallurgy (P/M), the strength of the matrix is expected to be enhanced by solution and precipitation strengthening of titanium (Ti), and the interface bonding between Gr and brass matrix is improved by interfacial reaction of Ti with Cu and Gr to form intermetallic compounds. The results show that the addition of Gr can significantly improve the cutting performance of brass, but it is at the expense of mechanical properties. With the introduction of Ti, the formation of submicron Cu2Ti4O particles and nano Ti clusters effectively improves the mechanical properties of brass matrix. Meanwhile, TiC reaction layer formed on the interface significantly strengthens the interfacial bonding between graphite and the matrix, which is the basis of ensuring the good cutting performance of brass. The original graphite/brass non-reactive interface is transformed into graphite/reaction layer/brass and brass/precipitates/brass dual-interface structure. This study lays a research foundation for the development of lead-free free-cutting brass composites.