Cu-TiB2 Composites Research Articles

Microstructure and properties of Cu-TiB2 composites prepared by mechanical stirring-assisted double-melt in-situ reaction

Microstructure and properties of Cu-TiB2 composites prepared by mechanical stirring-assisted double-melt in-situ reaction

Effect of Fe Element and Ultrasonic Vibration on the Microstructure and Mechanical Properties of the Cu-TiB2 Composites

Cu-(Fe-Ti)-TiB2 composites were prepared by in situ reaction and vacuum casting with and without ultrasonic vibration. The evolution of the microstructure and mechanical properties of the composite with the variation in Fe element was analyzed. The import of Fe elements could purify the matrix after in situ reaction and the formation of a nanoprecipitated phase, thus improving the strength of Cu-Fe-Ti-TiB2 composites. Meanwhile, compared with the traditional casting process, the Cu-Fe-Ti-TiB2 composites with ultrasonic vibration treatment exhibit uniform TiB2 particle distribution and better properties. The tensile strength and uniform elongation of the composite with a Fe content of 0.7 wt.% reached 511 MPa and 6.02%, increasing by 14.3% and 318% compared to the unalloyed composite, respectively. The tensile strength and uniform elongation of Cu-0.7Fe-Ti-TiB2 composite with ultrasonic vibration treatment increased to 533 MPa and 7.16%, respectively. The TiB2 microscale particles and Fe2Ti nanoscale precipitates with uniform distribution effectively impeded dislocation movement and recrystallization, which improved the tensile strength and stability at elevated temperatures.

Effect of ultrasonic vibration treatment on microstructure evolution and mechanical properties of Cu-TiB2 composites

The distribution of second-phase particles is crucial to the mechanical properties of particulate reinforced copper matrix composites (PRCMCs). Ultrasonic vibration treatment (UVT), as an effective technique to disperse second-phase particles in metallic melts, has been extended to treat PRCMCs using a SiAlON sonotrode. In this study, systematic experiments have been conducted to explore the effect of UVT on the microstructures and mechanical properties of in situ Cu-TiB2 composites. The results indicated an optimal duration of UVT for 3 min, featured by an improved distribution of TiB2 particles and superior mechanical properties of the as-cast composite. The ultimate tensile strength, yield strength, and elongation exhibited significant increases of 15.7%, 18.1%, and 36.1%, respectively, compared to the as-cast Cu-TiB2 composite without UVT. Furthermore, these experimental composites were subject to rolling deformation. The results once again demonstrated that the as-rolled Cu-TiB2 composite, treated with UVT for 3 min, stood out as the best. The ultimate tensile strength, yield strength, and elongation of the as-rolled Cu-TiB2 composite were 459 MPa, 422 MPa, and 7.0%, respectively. Based on the microstructural observation, the mechanism underlying the UVT-induced enhancement of mechanical properties was discussed in terms of the non-linear effects of ultrasound cavitation on liquid metals. This work can provide a strategy for producing high-performance PRCMCs through UVT.

Investigations on microstructure and mechanical properties of Mg-5wt.% Cu-TiB2 composites produced via powder metallurgy route

Magnesium alloy matrix composite reinforced with constant weight fraction of 5% Cu and various weight fractions of (0%, 5%, 10%, 15%) titanium diboride (TiB2) fabricated by Powder Metallurgy route. In this work, the mechanical properties like hardness, impact strength, compression strength, and wear rate of the Mg-Cu alloy and fabricated composites were investigated. The results showed that the addition of weight percentage of 15% TiB2 increased the hardness value about 58.56 HV, due to better bonding between the Mg-Cu and TiB2. Further, impact and compressive strengths improved, as the weight percentage of TiB2 increased. Uniform distribution of reinforced particles enhanced the impact strength and the work hardening effect improved the compression strength. Moreover, the wear rate decreased about 0.0112 mg by the addition of weight percentage of 15% TiB2. X-ray diffraction (XRD) analysis was carried out for each composition. Optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tests were conducted to study the characterization of the base alloy and the prepared new composite.

Quantitative Analysis of TiB 2 Particles and Properties of Cu-TiB 2 Composite Prepared by in Situ Reaction

Cu-TiB2 composites were prepared by combining in situ reaction and hot-pressing at different temperatures after ball-milling of the mixture powders of Cu, Ti and B. The reaction process of Cu-Ti-B system was discussed. By means of XRD, SEM, EDS and XPS, it is determined that TiB2 nano-particles are generated by in situ reaction in Cu-matrix. According to the calibration curve of TiB2 and Cu by XRD, the concrete synthesis rate of TiB2 in Cu-matrix at different sintering temperatures by external standard method was confirmed. The results show that in certain temperature range, the higher the temperature is, the higher the synthesis rate is, and the best synthesis rate of TiB2 is 99.27% at 1000 °C. Cu-1.5wt%TiB2 prepared at 1000 °C has the best properties, Its Vickers hardness (HV), electric conductivity (EC), flexure strength (FS), thermal expansivity (TE) and thermal conductivity (TC) at 100 °C are 125.68 MPa, 80.1% IACS, 755.2 MPa, 9.3×10−6 K−1 and 260 W/(m·K), respectively.

Study of enhanced dry sliding wear behavior and mechanical properties of Cu-TiB2 composites fabricated by in situ casting process

In this work, TiB2 particulate reinforced copper matrix composites were fabricated by casting method, based on in situ precipitation reaction between B and Ti elements to form TiB2 particles in molten copper. The microstructures of the Cu-TiB2 composites were characterized using SEM and TEM. The results show that TiB2 particles are successfully formed in the copper matrix and the interfaces between these particles and the matrix are clean and well bonded. The friction and wear characteristics of the Cu-TiB2 composites were determined by carrying out dry sliding tests on pin-on-disk machine under varying loads, sliding speeds and sliding distances. A comparison between the volume wear losses of the composites under different conditions shows a significant improvement in wear property of the composites with respect to the pure copper. Furthermore, the mechanical properties of the composites with different TiB2 levels were also investigated. Both tensile strength and hardness are significantly improved with the increasing amount of TiB2 in copper matrix, while compromises of the elongation and electrical conductivity nevertheless occur in all cases.

Preoblikovalnost Cu-TiB2 predoblik izdelanih z metalurgijo prahov med hladnim kovalnim preizkusom

An investigation was carried out to find the workability behaviour of a Cu-TiB2 composite under triaxial stress-state conditions. Initially, the TiB2 powder was prepared by using a self-propagating high-temperature synthesis (SHS) technique and the same was added to a Cu matrix in order to make Cu-TiB2 composites. Cylindrical preforms with three different TiB2 weight percentages (2 %, 4 % and 6 %) with aspect ratios of 0.50, 0.75 and 1 were prepared using a uniaxial load. Then the preforms were pressureless sintered in a tubular furnace with a continuous flow of pure argon gas at 950 °C for a period of 1 h. The cold upsetting test was carried out on the sintered specimens. The relationships between the various stresses, strains and the relative density were determined. The results for the various stress-ratio parameters, namely ( / eff) and ( m/ eff), the formability stress index ( ) under triaxial stress-state conditions were systematically analysed. The formability stress index was found to increase with the increase in preform fractional density and it decreased with the aspect ratios. This was because the preform contains more pores and the porous bed height is high. A statistical fitting method was performed on the curve drawn between the axial strain and the stress-formability index. The compacts with a higher value of the aspect ratio and the initial preform density showed a very high fracture strain.

Effect of La addition on the particle characteristics, mechanical and electrical properties of in situ Cu-TiB2 composites

In situ Cu-TiB2 composites can be synthesized via metallurgical process by mixing Cu-B and Cu-Ti master alloys before casting. In this paper, La, as a rare earth element was added to the composites to improve the comprehensive properties and the effects of its addition on the microstructures, mechanical and electrical characteristics of Cu-TiB2 composites were investigated. Results show that addition of La significantly diminishes the average size and facilitates a homogeneous distribution of TiB2 particles in the copper matrix. As a result, an improvement in mechanical properties was achieved. In particular, a remarkable change in the conductivity of the composites appears with the variation of La content. The mechanisms of particle refinement and improvements in properties by La alloying were analyzed.

A Survey on Electrode Materials for Electrical Discharge Machining

This work screens electrode materials used in EDM and proposes some potential electrodes for future industrial applications. Traditional graphite, W, and Mo EDM electrodes have low TWR due to their high melting points; while, Zn, brass, and Cu often experience too much tool wear. As to some newly developed alloy and composite materials, their machining performances depend on not only their melting points but also their microstructures. Cu-W alloy has high wear resistance but it is susceptible to shape loss due to its internal porosity. By contrast, Cu-graphite, Cu-ZrB2 and Cu-TiB2 composites show good capabilities of removing material with little wear loss and therefore could be promising for future usages.

In-situ processing of TiB2 nanoparticle-reinforced copper matrix composites

In order to produce the composite powder analyzed in this paper, two prealloys were melted and afterwards gas atomized. The obtained TiB2-reinforced copper powder was consolidated by hot isostatic pressing (HIP). Since it is known that a decrease in the size of the reinforcing phase can cause an increase in hardness of composites, the main aim of the experimental work was to obtain as small particles of the dispersed phase as possible by using standard powder metallurgy techniques. Microstructure and microhardness of the ascast prealloys, as-atomized powder and HIP-ed compacts were examined. The results of these examinations revealed that TiB2 particles about 10 nm in size were in-situ formed and homogenously dispersed in the copper matrix. As a consequence of the TiB2 formation, the microhardness of Cu-TiB2 composite was significantly improved.

Microstructural Study on the Wear Behavior of Cu-TiB<sub>2</sub> Composites for Electrical Contact Materials

We have studied on the wear behavior of Cu-TiB2 composites, produced by thermal extraction, as a function of dispersed particle sizes and volume fractions of TiB2. The depth of subsurface zone was increased with applied loads from 25 μm with 20 N to 25 μm with 80 N. From the analyses results of the formation of wear debris generated by cracks between work hardened layer and matrix, wear mechanism is changed from abrasive wear to adhesive wear with increasing loads from 20 N to 80 N. The formation of sub-grains in the region of subsurface was clearly observed from the sample tested over 60 N loads. We attribute the formation of sub-grains to the plastic lubricant effect of TiB2 which gives arising from the contact stress and local heat generated during wear test.

Investigation of In situ Cu-TiB2 Composite on the Copper Using Laser Melting Synthesis

A surface composite layer reinforced with TiB2 particles was produced on copper by use of the laser remelting in situ synthesis. The microstructure, electrical conductivity, and sliding wear behavior of the in situ Cu-TiB2 composite were investigated. The experimental results show that the size of reinforcing TiB2 particles is about 800 nm and the microhardness of composite layer reaches HV 210. Although the electrical conductivity of the composite layer is reduced with increasing TiB2 volume fraction, the decrease of the integrated conductivity of the samples containing composite layer and copper substrate is insignificant. The wear resistance of composite layer is 10 times better than that of the copper sample.

Effect of High-Energy Ball-Milling and TiB<sub>2</sub> Content on Microstructures and Properties of Cu-TiB<sub>2</sub> Composites Sintered by SPS

The microstructure and properties of Cu-TiB2 composites produced by high-energy ball-milling of TiB2 powders and spark-plasma sintering (SPS) were investigated. TiB2 powders were mechanically milled at a rotation speed of 1000rpm for short time in Ar atmosphere, using a planetary ball mill. To produce Cu-xTiB2 composites( x = 2.5, 5, 7.5 and 10wt.% ), the raw and milled TiB2 powders were mixed with Cu powders by means of a turbular mixer, respectively. Sintering of mixed powders was carried out in a SPS facility under vacuum. High-energy ball-milling resulted in refinement of TiB2 particles. XRD patterns of milled TiB2 powders indicated broader TiB2 peaks with decreased intensities. After sintering at 950 for 5min using the raw and milled TiB2 mixture powders, the sintered density decreased with increasing TiB2 content regardless of milling of TiB2. In the case of raw TiB2, hardness rapidly increased from 4 to 44 HRB with increasing TiB2 content. The electrical conductivity changed from 95.5 to 80.7 %IACS. For mixtures of Cu powders with milled TiB2 powders, hardness increased from 38 to 67 HRB as TiB2 content increased, while the electrical conductivity varied from 88% to 51 % IACS. When compared to compacts sintered with raw and milled TiB2 powders, the electrical conductivity of specimens with raw TiB2 powder was higher than that of specimens with milled TiB2 powder, while hardness was slightly lower.

Observation on the microstructures of Cu-TiB2 composites with wear behavior

Observation on the microstructures of Cu-TiB2 composites with wear behavior

Properties of Cu-TiB<sub>2</sub> Composites Fabricated by In-Situ Liquid Melt Mixing Process

A Cu-TiB2 composite was successfully fabricated by in-situ liquid mixing process, and its microstructure, mechanical properties as well as electrical conductivity were evaluated. For Cu-2vol.%TiB2 composite, the hardness was as high as 5GPa and the Young’s modulus was 130GPa. And hardness and Young’s modulus of Cu-6vol.%TiB2 composite was 5.6Gpa and 138GPa, respectively. With the increase of the TiB2 content, hardness and Young’s modulus of Cu-10vol.%TiB2 composite were 20 and 12%, respectively, which was higher than that of Cu-2vol.%TiB2 composite. Young’s modulus of the Cu-TiB2 composite in this paper was in good agreement with the prediction by Hashin-Shtrikman (H-S) model. Furthermore, the electrical conductivity of the Cu-TiB2 composite showed its maximum value of about 78%IACS and decreased with the increase of the TiB2.

The characteristics of wear resistance of Cu-TiB2 composites reinforced by TiB2 powders

In this study the effect of the content of <TEX>$TiB_2$</TEX> on wear properties was investigated. <TEX>$Cu-TiB_2$</TEX> composites have been fabricated by hot extrusion. Sliding wear tests were peformed by a pin-on-disk type wear test machine under dry condition and loads varied with from 20N to 80N at sliding speed 3.5Hz. The test results showed that the wear losses and the friction coefficients decreased with increasing <TEX>$Cu-TiB_2$</TEX> volume fraction and increasing the size of <TEX>$Cu-TiB_2$</TEX> particle. Wear property of <TEX>$10{\mu}m,\;5 vol\%\; TiB_2$</TEX> specimen was excellent all of the wear specimens. It is thought that the increase of plastic flow resistivity due to uniform distribution of <TEX>$10{\mu}m,\;5 vol\%\; TiB_2$</TEX> wear specimen would improve wear property. The worn surface and wear debris were examined by optical microscope and scanning electron microscope.

A Study on the Wear Behavior of the Cu-TiB2 Composites

The titanium <TEX>$diboride(TiB_2)$</TEX> has high strength(750MPa), high melting point <TEX>$(3225^{\circ}C)\;and\;10\%$</TEX> IACS electrical conductivity. On this account, the dispersion hardening <TEX>$Cu-TiB_2$</TEX> composites(MMCs) are a promising candidate for applications as electrical contact materials. MMCs for electrical contact materials can reduce material cost and resource consumption caused by wear, due to its good mechanical and electrical property. In this study, we attempt to prepare MMCs with various volume fraction and particle size of <TEX>$TiB_2$</TEX> by means of hot extruded and cold drawn process. Dry sliding wear tests were performed on a pin-on-disk type wear tester, sliding against SM45C under the different applied loads. After wear testing, the microstructures of the worn surfaces were observed by SEM and the microhardnesses of the subsurface zone were measured.

The Influence of TiB2 Particle on the Mechanical Property of Cu-TiB2 Composites

The mechanical and electrical properties of <TEX>$Cu-TiB_2$</TEX> composites prepared by hot extrusion and cold drawing according to the variation of <TEX>$TiB_2$</TEX> contents and the size of <TEX>$TiB_2$</TEX> particle have been studied. The experimental results showed that the electrical conductivity was decreased with increasing the <TEX>$TiB_2$</TEX> content, and their tensile strength and hardness increased inversely. In the case of the same content of <TEX>$TiB_2$</TEX> particle, the smaller <TEX>$TiB_2$</TEX> particle, the higher their mechanical properties. The electrical conductivity of <TEX>$Cu-TiB_2$</TEX> composites showed more than 70%IACS. Their yield strength and hardness were more than 120 MPa and HRB 60～70, respectively.

Strengthening mechanism of a spray-formed Cu-TiB2 composite

Cu-TiB2 composite has been manufactured by spray forming process. The microstructures of over-sprayed powder, spray-formed billet, and extruded rod have been characterized by optical microscopy and x-ray diffractometry. The tensile strength of extruded rod was measured by tensile testing. TiB2 particles were formed in a Cu melt of 1500°C by chemical reaction between Ti and B. The TiB2 volume fraction within the spray-formed billet varied by the density difference between TiB2 and Cu melt. The strengthening of Cu-TiB2 alloy was well described by dislocation pile-up model. The results indicate that yielding of this composite was subject to reinforced particle fracture by local stress concentrations caused by dislocation pile-up between obstacles. Reinforcement fracture also has an effect to decrease the work hardening rate with the increase of reinforcement volume fraction during plastic deformation. We believed that this is because of the strengthening loss due to the increase of fractured particles with increasing TiB2 volume fraction.