Reinforced Copper Matrix Composites Research Articles

Preparation, mechanical properties and strengthening mechanisms of T15 particles reinforced Cu matrix composites

High speed steel T15 particle reinforced copper matrix composites were prepared using powder metallurgy. A systematic investigation was conducted into the effects on the microstructure and mechanical properties of the composites of the sintering temperature, T15 hard particle content, and particle size. The results indicate that the grain size is efficiently refined by the addition of T15 hard particles. The decrease in grain size of 10 wt.% T15/Cu composite is from 6.87 μm to 1.34 μm at the same sintering temperature, and the grain size is proportional to both the sintering temperature and the size of hard particles. As the sintering temperature increases, the relative density and hardness of the composite gradually increase, while the yield strength initially increases and then declines. When sintered at 790 °C, the 10 wt.% T15/Cu composite achieved a maximum yield strength of 160.1 MPa, which is 178.9% and 30.6% higher than that of pure copper and 10 wt.% TiC/Cu composites, respectively. There are no visible cracks after compression, and a good balance of strength and toughness is achieved. Meanwhile, the primary contributions of strengthening mechanisms such as grain refinement, thermal expansion mismatch and load transfer to the mechanical properties of T15/Cu composites were analyzed. It is anticipated that this will establish a foundation for the preparation and application of high-performance copper matrix composites reinforced with metal particles.

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.

Enhanced mechanical and tribological properties of copper matrix composites reinforced by copper-coated graphite and Ti3AlC2

To solve the poor mechanical properties of graphite-reinforced copper matrix composite, the effect of Ti3AlC2 content on the mechanical properties and dry sliding properties of copper-coated graphite reinforced copper matrix composites was investigated. The results show that the in-situ TiCx-Ti3AlC2-Cu(Al) gradient interface is formed due to the decomposition of partial Ti3AlC2 particles, which can improve the interface bonding strength and enhance the mechanical properties of the composites. With the Ti3AlC2 content increasing, the hardness, yield strength, and tensile strength of the composites increase, while the elongation decreases. The composite reinforced by copper-coated graphite and 5 wt% Ti3AlC2 shows a higher yield strength and tensile strength, increased by 86.2% and 28.6% over the neat Cu, respectively. Besides, the composites exhibit better wear resistance compared with the neat Cu. The wear rate of the composites decreases as the increase of Ti3AlC2 content. The wear mechanism changes from delamination wear of pure Cu to adhesive wear, abrasive wear, and oxidative wear for the composites reinforced by copper-coated graphite and 10 wt% Ti3AlC2.

Engineering performance of tungsten network reinforced copper matrix composites synthesized by selective laser melting and infiltration

ABSTRACT To solve poor engineering performance of copper-tungsten alloys operated at high temperatures, 3D network tungsten frameworks were prepared using a selective laser melting (SLM) process, and then copper was melted and diffused into these tungsten network structures to form copper matrix composites with different copper contents (i.e. Cu-10vol%W and Cu-30vol%W). Their mechanical/electrical properties and arc ablation performance were characterized. Results showed the obtained CuW composites were dense with good interfacial bonding, and the connected Cu phases formed a heat conduction channel and improved electrical and thermal conductivities of the composites. Electrical conductivities of Cu-30W and Cu-10W composites were 44.7% and 80.3% IACS, and their thermal conductivities at 25°C were 247.5 and 375.4 W/(m·K), respectively. The W-skeleton grid structure in the composites showed enhanced effects on impact toughness and anti-friction/wear resistance. Tensile strengths of Cu-30W and Cu-10W composites measured at 300°C were 95 MPa and 135 MPa, and their impact toughness values were 11.25 and 15.25 J/cm2, respectively. For the arc ablation performance, the copper phase of CuW composite was identified as the key influencing phase, whereas the W skeleton effectively hindered the spread of arc spots, inhibited quick melting of copper phases, and played effective support and protection functions.

Reinforcing or weakening? Determined by the interfacial nanostructures in graphene reinforced copper matrix composites

Graphene reinforced copper matrix composites (Gr/Cu) has been intensively studied, however, precisely controlling interfacial structure, understanding the reinforcing or weakening mechanism at nanoscale are still scientific problems by experiment method. Using a molecular dynamics simulation method, we examined the intrinsic relationship between nanostructures and evolutions mechanisms of various Gr/Cu composites. It was found that reinforcement of the Gr/Cu composites interface was dependent on its nanostructures. Under compression loading, interface with Gr/Cu{100} was more likely to experience a plastic deformation comparing to Gr/Cu{111} and Gr/Cu{110} interfaces. Graphene could lubricate the atoms migration at the Gr/Cu{100} interface but hinder these process at the Gr/Cu{111} and Cu{110} interfaces. Dislocation analysis confirmed that Shockly (1/6 〈112〉) dislocation was a main factor affecting the interface evolutions and dislocation propagation was limited by graphene sheets at the interface. Besides, the face-centred cubic (FCC) to hexagonal close-packed (HCP) transition induced by formation of stacking faults were observed to dominate in plastic deformation under higher compression strains to some extent, and the graphene sheet in grain boundaries could reverse the transition direction, which kept the plastic deformations under high compression strain more stable. Our findings may provide more insight to understand the interface characteristics-deformation relation of the graphene reinforced copper matrix composites.

Defects induced the bilayer graphene-copper hybrid and its effect on mechanical properties of graphene reinforced copper matrix composites

Graphene/Cu composites have shown great potential in the fields of mechanical engineering, electronic devices and so on. In this study, the impacts of vacancies on the interlayer interaction of bilayer graphene (BLG) and the resultant influence of graphene interlayer bonding on the interfacial bonding, tensile strength, and slipping mechanism of the graphene/Cu composites are comprehensively investigated based on first-principles calculations. It was revealed that clustering of cross-layer vacancies (CV) can initiate the formation of distinct hybrid types (sp2 hybrid, sp3 hybrid) of interlayer bonds, resulting in enhanced interlayer bonding of BLG. Unlike the van der Waals interaction between graphene and Cu, vacancies cause the Cu atoms on the surfaces to be embedded in the BLG, forming the graphene-copper hybrid that can improve the combination of Cu and graphene. The notable hybridization between the 2p orbitals of the unsaturated C atoms neighboring the vacancies and the 4s, 3d orbitals of the Cu atoms on the surfaces drives this effect. BLG with interlayer bonds can substantially improve the interfacial bonding and mechanical properties of the composites. This research provides a novel outlook for the interface engineering research and innovative development of graphene/Cu composites by regulating the interlayer bonding of grapheme.

Exceptional dynamic compressive properties of bio-inspired three-dimensional interlocking graphene network reinforced copper matrix composites

Insights into the reinforcement spatial architectures and their fundamental effects on the dynamic mechanical behaviors are of great importance for designing shock-resistant metallic structures. In this study, we report copper matrix composites (CMCs) reinforced by three-dimensional interlocking graphene network (3D-IGN) with a unique bio-inspired “brick-bridge-mortar” structure. Our results demonstrate that the 3D-IGN/Cu shows simultaneously enhanced dynamic strength and ductility as compared to the uniformly-distributed RGO/Cu and pure Cu at the specific strain rate from 1000 s−1 to 8000 s−1. The interlocking network structure not only blocks dislocation movement and restricts grain boundary sliding, but also alleviates the heat-induced softening by improving the thermal conductivity in the horizontal direction. The finite element simulation results further confirm the important role of the graphene network on strain delocalization. This work offers a promising bottom-up tactic to fabricate CMCs with network architecture and superior dynamic properties for high-rate applications.

Microstructure and properties of TiC–Ti5Si3 reinforced copper matrix composites

In this study, Ti5Si3 single-phase and TiC–Ti5Si3 hybrid phases reinforced copper matrix composites with different volume fractions were prepared by melt reaction. The microstructures and mechanical properties of the composites were analyzed to investigate their wear and tensile mechanisms. The wear resistance of the composite materials exhibits a non-linear behavior with increasing load, initially decreasing and then increasing, reaching its lowest point at 7.35 N. At higher loads, such as 9.8 N, the composites form a more stable and effective wear-resistant layer, exhibiting the positive impact of the reinforcing phase on wear resistance. Furthermore, as the content of the reinforcing phase increases, the brittleness of Ti5Si3 also increases, along with the expansion of the interface between the reinforcing phase and the matrix. This results in a transition of the wear mechanism from delamination wear to abrasive wear and an increased likelihood of spalling under shear forces. Therefore, the composite material achieves optimal wear resistance when the Si content is at 1%. In addition, the TiC and Ti5Si3 phases within the Cu matrix not only effectively bear the load but also impede crack propagation, resulting in a shift in the fracture mode of the composites from ductile fracture to cleavage fracture or quasi-cleavage fracture as the reinforcement content increases. Finally, hot rolling proves to be an effective method for refining the reinforcement and improving its uniformity, leading to significant enhancements in tensile strength and ductility. However, the reinforcement causes a disruption in the continuity of the matrix, resulting in a reduced elongation in the composite material with a Si content of 1% after the hot rolling process.

Fabrication of graphite-Ti3AlC2 synergistically reinforced copper matrix composites

Copper-graphite composites find extensive application as electrical contact materials. However, their tribological properties are limited by the weak interfacial bonding. In this study, Ti3AlC2 was used to modify copper-graphite composites fabricated by vacuum sintering. The incorporation of Ti3AlC2 included both coated Cu and uncoated Cu. The hardness, relative density, tribological properties, and microstructure of the composites were thoroughly investigated. The results show that the addition of Ti3AlC2 coated with Cu was conducive to avoiding the agglomeration of Ti3AlC2 particles, and resulting in superior relative density, hardness, lubrication and wear resistance of the composites. Furthermore, the incorporation of Ti3AlC2 not only enhanced the presence of lubricating components in copper-graphite composites but also improved the interface bonding strength between the copper matrix and graphite. Specifically, Cu-graphite-Ti3AlC2 (Cu-coated) composites displayed a relative density of 92%, a hardness of 94.2 HV, a friction coefficient of 0.175, and a wear rate of 1.28 × 10−6 mm3/N·m.

In-situ synthesized graphene reinforced copper matrix composites with enhanced thermal properties and corrosion resistance

Graphene is expected to comprehensively improve the thermal conductivity and corrosion resistance of metals to satisfy the need of adverse electrochemical environments. However, there are some major concerns in the mixing methods such as, low quality of graphene, non-uniform dispersion, and poor interface bonding with the metal matrix. In this study, we propose an effective approach to fabricate Cu-graphene (Cu/G) nanocomposite by sintering in-situ growth of graphene on Cu nanoparticles. Results confirmed the firmly adhesive graphene on Cu surface, which closely linked Cu particles to building a bulk, particularly binding between Cu particles and graphene flakes is largely improved by the sintered progress. The as-prepared Cu/G heat spreader demonstrated higher thermal conductivity (376 W/(m·K) at room temperature and lower thermal expansion. Additionally, the short-time corrosion resistance showed that Cu/G can build a graphene network to avoid the penetration of active species and enhance the passivation layer. This work endows Cu/G integral materials possessing good thermal conductivity and corrosion inhibition, which can effectively serve as potential offshore materials.

Freeze-casted tungsten skeleton reinforced copper matrix composites

Copper-tungsten (Cu-W) composites with a copper content larger than 50 vol% are expected to have a good combination of electrical conductivity and mechanical properties. However, it is difficult to synthesize these types of composites using the conventional manufacturing routes. In this paper, W skeletons with a high porosity up to 80 ± 0.8% and well-aligned microstructures were prepared by directional solidification of aqueous slurries of W followed by ice sublimation and heat treatment. Tungsten reinforced copper matrix composites (e.g., Cu-15 vol% W composites) were fabricated by infiltration of Cu into the W skeleton structures, and their microstructure, electrical conductivity and mechanical properties were studied. The synthesized Cu-15 vol% W composites exhibited alternately patterned Cu and W microstructures and showed a good combination of electrical conductivity of 78 ± 2% IACS and hardness of 136 ± 6HV. The strengthening mechanisms of these Cu-15 vol% W composites were identified as the formation of tungsten network structures which support and strengthen the copper matrix. Residual pores in the W lamellae and weak interfaces of copper-tungsten caused the initiation and propagation of cracks, and the fracture mode of Cu-15 vol% W composite was polymerization induced ductile fracture.

Microstructure, properties and synergetic effect of graphene oxide-functionalized carbon nanotubes hybrid reinforced copper matrix composites prepared by DC electrodeposition

As the prospective carbon materials, graphene oxide (GO) and carbon nanotubes (CNTs) have attracted extensive attention in the fabrication of copper matrix composites (CMCs), but how their orientation and synergetic effect in Cu matrix affects the properties of composites has not been explored systematically. Herein, an efficient route to fabricate CMCs with GO-CNTs hybrid reinforcement had been reported, as well as the influence of different carbon reinforcement and different current densities on the texture orientation, microstructure and the comprehensive performance were investigated. From ultraviolet–visible results, it was found that one-dimensional CNTs bridge adjacent two-dimensional GO through π-π bonding to form an interconnected network structure. By adding GO-CNTs hybrid reinforcement to pure Cu sulfate, the preferred crystalline orientation of the GO-CNTs/Cu had been changed and a preferred orientation of (111) crystal plane was formed. Meanwhile, the EBSD results revealed that the GO-CNTs hybrid reinforcement had significant grain refinement effect and the average grain size of GO-CNTs/Cu composite reduced to 112 nm. According to TEM images, the lattice stripes between GO and CNTs indicate the formation of C–C covalent bonding. Owing to the synergistic effect and the C–C covalent bonding between GO and CNTs, the highest thermal conductivity reached to 527 W m−1 K−1, while, the highest hardness was up to 226.8 HV0.1, the friction coefficient reduced to 0.62and excellent corrosion resistance of the GO-CNTs/Cu composite were also achieved. This study suggested that the promising fabrication of high-oriented GO-CNTs/Cu composite may have the potential to obtain excellent performance.

Achieving excellent thermal stability in continuous three-dimensional graphene network reinforced copper matrix composites

The stabilization of ultrafine crystalline grains is a tough issue for developing high-performance copper (Cu) matrix composites towards the application in the electronic industries. In order to solve this problem, here we introduced the construction of a three-dimensional graphene network (3DGN) in the Cu matrix to boost the stabilization of both the bi-crystal grain boundaries and the triple junctions. Mechanical properties tests demonstrated that 3DGN/Cu possessed an excellent thermal stability up to 0.9Tm and high-temperature Vickers hardness, which are much higher than those of pure Cu and composites reinforced by two-dimensional (2D) reduced graphene oxides nanosheets. Microstructure characterization revealed that during the hot-rolling (HR) deformation, 3DGN had a strong pinning effect on the recrystallized Cu grains with high-angle grain boundaries and improved the intragranular dislocation density as well as the fractions of the low-angle grain boundaries thus resulting in retaining the equiaxed grain shape and ultrafine grain size. The experimental and molecular dynamics (MD) simulation results both indicated that the key point of attaining the high stability of the graphene/Cu composites lied in the effective restriction of the grain boundary triple junctions migration. These findings may provide guidance for promoting the thermomechanical properties of 2D nanomaterials/Cu composites.

Reinforced copper matrix composites with highly dispersed nano size TiC in-situ generated from the Carbon Polymer Dots

In order to uniformly disperse the ceramic reinforcements synthesized in situ in the copper matrix composites, this study used Carbon Polymer Dot (CPD) as the carbon source and Cu-1.0%Ti alloy powder as the matrix to supply the Ti source for manufacturing in situ synthesized TiC/Cu composites. The results showed that TiC nano-precipitate formed in the grains interior and grain boundaries, with particle sizes that were similar to the CPD size and maintained a uniform distribution state. Compared with the matrix, 0.3 wt% CPD/Cu composite displayed the best strength-plastic compatibility, the UTS had achieved to be 385 MPa accompanied with a corresponding EL of 21%. This was owing to the dislocation hindrance caused by nano-carbide and excellent interface bonding between nano TiC and the Cu matrix. The density function theory calculation had supported our experimental results, which showed a tighter and stronger interface contact. This paper presents a new approach for studying in situ carbide precipitates. To create the in situ synthesized nano-sized TiC/Cu composites, Carbon Polymer Dot (CPD) was used as the carbon source. Theoretical and experimental findings support the strong interfacial bonding between TiC and copper matrix. The proposed method of in-situ synthesized nano-scaled TiC demonstrates to be a novel way to construct high-performance Cu matrix composites with both enhanced strength and plasticity.

A Study of Silver Decoration on Carbon Nanotubes via Ultrasonic Chemical Synthesis and Their Reinforced Copper Matrix Composites.

The homogeneous distribution of carbon nanotubes (CNTs) in the Cu matrix and good interfacial bonding are the key factors to obtain excellent properties of carbon nanotube-reinforced Cu-based composites (CNT/Cu). In this work, silver-modified carbon nanotubes (Ag-CNTs) were prepared by a simple, efficient and reducer-free method (ultrasonic chemical synthesis), and Ag-CNTs-reinforced copper matrix composites (Ag-CNTs/Cu) were fabricated by powder metallurgy. The dispersion and interfacial bonding of CNTs were effectively improved by Ag modification. Compared to CNTs/Cu counterparts, the properties of Ag-CNTs/Cu samples were significantly improved, with the electrical conductivity of 94.9% IACS (International Annealed Copper Standard), thermal conductivity of 416 W/m·k and tensile strength (315 MPa). The strengthening mechanisms are also discussed.

Study on Sliding Wear Characteristics of Tungsten Carbide Particle Reinforced Copper Matrix Composites Under Electrical Contact

Tungsten carbide (WC) particles reinforced copper (Cu) composites (1⁓5 wt.% WC/Cu) were fabricated by a hot-pressed sintering process and their mechanical, electrical properties and sliding wear behaviors were studied. The results show that the relative density and electrical conductivity of the sintered composites decrease whereas the microhardness increase, with increasing the mass fraction of WC reinforcements. During the sliding wear tests without electrical current, the wear rate of the WC/Cu composites decreases with an increase of WC reinforcement mass fraction. The increase in the normal load leads to the increase of wear rate. The wear rate under electrical contact increases with the increase of electrical current density. The dominant wear mechanism under electrical contact sliding conditions is the combination of the abrasive wear and oxidations resulted from electrical currents. The WC/Cu composites are promising electrical contact materials to restrain spark/arc discharge during the electrical contact sliding.

In-situ synthesis of TiB2 particulate reinforced copper matrix composites with ultrasonic vibration treatment

In this paper, ultrasonic vibration treatment (UVT) was directly introduced into Cu-Ti-B melt through a Sialon sonotrode. The effects of UVT on the microstructures and properties of TiB2/Cu composite thus fabricated were investigated. The results indicate that with the application of UVT, the average size of the particle agglomerates in the as-cast composite reduced from 24.84 μm to 19.69 μm. Besides, the 3D morphology of the agglomerates changed from irregular to near-spherical under the effect of ultrasound cavitation. The acoustic streaming promotes the flow of the melt to realize a more uniform distribution of particles in the bulk. Dispersion of TiB2 particles alleviates the stress concentration caused by coarse agglomerates, resulting in the concurrent improvements in both strength and ductility of the composite.

Tribological, mechanical and thermal response of diamond micro-particles reinforced copper matrix composites fabricated by powder metallurgy

Copper/Diamond composites have gained a lot of attention in recent years due to their excellent thermal conductivity and their potential for use in high-power electronic devices. The current work targets on an experimental investigation of the tribological,mechanical, and thermal behaviour of copper diamond composite by using reinforced micro-diamond particles. Copper matrix composites with varying weight percentages of diamond particles were produced with the aid of the powder metallurgy. The wear tests were carried out on Pin-on-Disc wear test machine as per ASTM G99. The doping of an optimum amount of diamond particles (1% wt.) improved the overall wear performance by 51% under a normal load of 80 N. The doping had also showed a significant improvement in hardness by 26% and thermal conductivity by 1%. The primary wear mechanisms of Cu-Diamond composites appear to be a combination of brittle fracture, fragmentation of diamond-reinforced particles and ploughing in the Cu-alloy matrix.

Flow induced fiber orientation in short carbon fiber reinforced copper matrix composites

This study investigated the effect of a distinctive design of mold to align short carbon fiber in copper matrix composite produced via metal injection molding. The mold was designed to improve the fiber orientation during flow in the core region of test samples. The composite feedstocks comprising polymeric binder and Cu powder reinforced with 0, 5 and 10 vol. % carbon fiber, prepared in Z-blade mixer, were injection molded to fabricate green samples. Green samples were debound to remove the binder and sintered in sintering furnace at 1050 °C in Argon atmosphere. Dispersion of carbon fibers was examined in composite feedstocks and TGA was used to determine the degradation temperature of binder. Uniform dispersion of carbon fibers was observed in compounded feedstocks, green and sintered samples. Fiber orientation was quantified at various locations of skin and core of the green and sintered samples. Quantification of fiber orientation showed the best value of more than 90% of short fibers aligned in green test samples whereas sintered samples demonstrated just above 70% of fiber alignment in the flow direction in Cu-10%CF at section N. Overall, the results showed fiber alignment within ±22.5° in both green and sintered samples without significant skin-core effect. Moreover, the calculated mechanical properties increased with an increase in alignment of carbon fiber in the Cu matrix. Conclusively, fiber alignment can be improved by controlling flow of molten feedstock during molding with potentially high mechanical properties of composite.

Deformation and fracture mechanisms of selective laser melted tungsten skeleton reinforced copper matrix composites at varied temperatures

Tungsten skeleton reinforced copper matrix composites (TRC) were designed and fabricated using a selective laser melting (SLM) method followed by infiltration sintering. Deformation and fracture mechanisms were investigated at 25, 300 and 500 °C. Compressive and tensile tests of the tungsten skeletons showed brittle fracture mode, whereas tensile tests of the TRC exhibited a mixed mode of ductile and brittle fracture. Fracture mechanisms of the TRC were identified as cleavage of tungsten and separation between copper and tungsten at 25 °C. Whereas at 300 and 500 °C, its fracture mechanisms were identified as intergranular fracture of tungsten particles, tearing of copper and separation between copper and tungsten.