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POWDER METALLURGICAL FABRICATION OF CO REINFORCED CUNISI MATRIX COMPOSITES: MICROSTRUCTURAL AND CORROSION CHARACTERIZATION
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In this study, composite samples were produced by supplementing the CuNiSi powder mixture with Ti particles at different weight ratios using the powder metallurgy (PM) method. The prepared CuNiSi and Ti powder mixtures were turned into pellets by cold pressing under 500 MPa pressure. The pelletized samples were subjected to sintering in an atmosphere-controlled oven at 900 ℃ for 2 hours. Scanning electron microscopy (SEM-EDS), SEM-Mapping and corrosion experiments were performed to determine the microstructures of the produced samples. From the microstructure results, it was determined that Ti particles were distributed homogeneously within the structure. As the amount of Ti increased, the resistance of the composite to corrosion increased. In addition to that, as the amount of Ti increased, the resistance of the composite to corrosion decreased.
This study examined the effects of hot rolling on the microstructure, tensile strength, and corrosion behaviors of three different alloy steels made by powder metallurgy: Fe-0.55C, Fe-0.55C-3Mo, and Fe-0.55C-3Mo-10Ni. 700 MPa pressure was applied to press the particles. The cold pressed samples were sintered in a mixed-gas atmosphere (90% nitrogen, 10% hydrogen) at 5?C/min up to 1400?C for 2 hours. Then, the produced steels were hot rolled with a deformation rate of 80%. The microstructures show that deformed Mo and Mo-Ni steels have finer microstructures, better mechanical properties than undeformed Mo and Mo-Ni steels, and MoC, MoN, or MoC(N) was formed in the Mo-Ni steels. The highest mechanical properties were obtained in rolled steel samples containing Mo-Ni, followed by rolled Mo steel and rolled carbon steel samples, and then unrolled samples. Additionally, Tafel curve analysis demonstrated that alloy corrosion resistance rose as Ni concentration increased. It has also been observed that the hot rolling process improves corrosion resistance. The increase in the density value with the rolling process emerged as the best supporter of corrosion resistance.
Improving microstructural, mechanical, and thermal properties of Ni-Co-Bronze composites is crucial for various applications. In this study, five Ni-Co-Bronze (CuSn) + XTiC (0, 3, 7, 10, and 15 wt.%) composites were produced by using the hot pressing method. The effect of TiC reinforcement rate on each of their microstructure, wear, hardness, and thermal properties was investigated. Within the scope of microstructure analysis, the scanning electron microscope (SEM), electron dispersive spectrometer (EDS), and XRD analysis were employed. Thermal analyses were carried out for thermal differences between the samples. Furthermore, microhardness, impact, and wear tests were run to estimate mechanical behaviors of Ni-Co Bronze + XTiC composite. Experimental results indicated that TiC rate had an important effect on the microstructure, wear-resistance and microhardness of Ni-Co bronze composite. As the TiC reinforcement rate increased, the hardness of Ni-Co Bronze + XTiC composites varied between 180 HV and 450 HV. Consequently, microstructure analysis revealed that there was a serious interaction between reinforcement and matrix. Wear resistance increased with a TiC (7-10) wt. % rate but decreased at high TiC rates. It was clearly seen that the wear pattern was both oxidative and abrasive.
AlCuMg and its alloys are the most preferred composite materials in areas such as automotive, aerospace and aerospace industries due to their positive properties such as high corrosive properties, heat resistance, high strength and toughness. However, the inadequacy of these alloys in terms of wear and mechanical properties is one of the problems encountered in the industry. As a result of the literature review, it has been determined that there are almost no studies to improve the mechanical properties of these alloys. In this study, MoSi2 particles in different percentages were added to AlCuMg matrix and produced by powder metallurgy method. The aim is to improve the mechanical properties of AlCuMg matrix composite material and to perform characterization processes. Molten salt shielded synthesis/sintering process was used as a protective atmosphere environment for the produced samples to protect them from oxidation during sintering. In salt-protected synthesis, potassium bromide (KBr) was preferred as the salt. After the synthesis process, Scanning Electron Microscope (SEM), Energy Dispersion Spectroscopy (EDS), X-Ray Diffractometry (XRD) analyzes were applied respectively as characterization processes. In addition, microhardness test was performed to determine the mechanical properties of the produced composites. It has been determined that MoSi2 particles reinforced to AlCuMg alloy increase the mechanical properties of AlCuMg composite material because they have high values in terms of hardness and melting temperature.
The purpose of this study was to produce a metal matrix composite by adding TiC into a Ni-based matrix with the tungsten inert gas method and to measure the wear performance. TiC powder was added into the NiCrBSi alloy
powders. With increasing current values, decreases in the pore ratio and increases in the density of the eutectic structures and the thickness of the coating layer occurred. In addition, it was determined that increasing energy input improved the mechanical properties. According to XRD results, it was seen that Ni3B, γ-Ni, CrB, Cr2B, M23C6(Cr23C6), M3C(Fe3C), and TiC complex carbide and boride phases were formed in the coating and the hardness values of these phases increased in the range of 2–2.5 times. Wear tests showed that the hard carbide and borides in the structure caused an overall reduction in the coefficient of friction and weight loss values of the coating layers.
Due to the increasing demand for electrical energy in modern society, there is a huge requirement for conducting materials and, due to the development of electromobility, this demand is forecasted to grow each year. This is one of the reasons why copper and copper alloys manufacturing and processing industries tend to evolve and improve. One of the improvement paths is the design of new conducting materials for electrical power systems, electrical energy transmission, and energy storage systems. This paper presents a comparative study on obtaining high-strength copper magnesium alloys in terms of the alloy additive used during the metallurgical synthesis process, because this is a crucial, initial element in obtaining the final conducting product, such as wires. The obtained ingots were tested in terms of their chemical composition, and mechanical and physical properties. The provided results prove that there is a significant increase in the materials’ hardness (and thus the ultimate tensile strength), and a slight decrease in density, impact resistance, and electrical conductivity, as the Mg content increases. Scanning electron microscopy (SEM) and phase analysis were additionally conducted in order to determine the distribution and origin of Mg precipitations. Collectively, the results show that the CuMg alloys may successfully replace other alloys, such as CuNiSi or CuZn, as carrying and conducting materials because their properties are superior to those of the aforementioned materials.
In this study, microstructure and mechanical properties of nickel matrix B4C
reinforced functionally graded composites produced by powder metallurgy
method were investigated. Samples with Ni+5% B4C, Ni +10% B4C, Ni+ 15% B4C
and Ni+ 20% B4C compositions were sintered at 900 and 1050°C for 60
minutes. Microhardness and wear tests along with optical microscopy,
scanning electron microscopy with energy-dispersive X-ray spectroscopy
(SEM-EDX) and X-ray diffraction (XRD) analyses were carried out to determine
the mechanical properties, microstructure and phase composition of the
samples. The results indicated that hardness and wear resistance increased
with increases of B4C amount in nickel matrix.
In this article, the microstructures, mechanical properties, impact strength and corrosion behaviour of AA2024 matrix Al2O3- and SiC-reinforced hybrid composites obtained by using powder metallurgy (T/M) method, which is one of the production methods, were investigated. AA2024/Al2O3–SiC powder mixtures are prepared in different ratios and kept at 560ºC for 120 min and then compressed at 500 MPa pressure. In order to determine the microstructure and mechanical properties of the produced samples, microhardness, density, tensile, corrosion and free drop tests were performed with SEM, EDS and XRD images. According to the test results, the best tensile test result of AA2024/Al2O3–SiC hybrid composite materials was determined in hybrid composite materials with 2% reinforcement. The hardness values increased with an increasing reinforcement ratio. As the reinforcement ratio of the materials increases, the corrosion rates decrease, while the corrosion rates increase continuously after the 2% reinforcement ratio. The lowest corrosion rates were determined for hybrid composite materials reinforced with 2% (1.23 mpy). As a result of the drop test, hybrid composite materials with 2% (29.266 kJ m−1) reinforcement gave the highest value and drop test values decreased at higher reinforcement ratios.
The CuNiCoSi alloy is a promising precipitation strengthening Cu alloy, while the high content of alloy elements in it increases the difficulty of solid solution, thus it is essential to understand the evolutions of the alloy during solid solution. In this study, the cold-rolled CuNiCoSi alloy were precisely solid solution treated for 15-120 s and then partially aged, and the influences of solution time (ST) on the precipitates, microstructure and properties of the alloy were investigated. High density (Ni,Co)xSi precipitates, dislocations and deformation texture were found in the cold-rolled CuNiCoSi plate. Decomposition of the precipitates, elimination of the dislocations and grain recrystallization occur during the solid solution between 15 and 30 s. Then, the grain size grows with increasing ST but the residual precipitates change little. The strength of the solution treated specimens decreases with increasing ST, while that of the solution+aging treated specimens increases with increase of the previous ST, and both become almost stable after solution for over 30 s. It is demonstrated that recrystallization and precipitates decomposition of the cold-worked CuNiCoSi alloy occur within a short time at a high solid solution temperature, and sufficient decomposition of the precipitates with little grain coarsening can be achieved through reduce and precise control the ST, while prolonging the ST is negative to the strength and ductility of the alloy
Copper–nickel alloy has the potential in sustaining the recent demands in advanced marine engineering applications. It has been found advantageous over other copper alloys due to the unique properties and corrosion resistance they possess. However, the structure of Cu–Ni alloy alone is not sufficient to withstand many applications, as the structure cannot perform efficiently in an aggressive environment. The performance of this alloy inherently depends on carefully select alloying compositions, as the alloying elements are associated with the precipitation of intermetallic particles that will enhance mechanical properties and corrosion resistance when designing the component of Cu–Ni alloys. A combination of alloying elements has been conceptualized in the designing of copper–nickel alloy. This review described the role of alloying elements in modifying the microstructural features through phase transformation and how it affects the improvement of the mechanical and physical properties of Cu–Ni based alloys. The effect of alloying elements on the structure and properties of Cu–Ni alloys have been critically summarized based on surveying the works done by authors on this category of structural modification binary Cu–Ni alloy.
An in-depth exploration of the microstructure evolution and characterization of the dislocation density in Cu–Ni–Si–Co alloy was performed using X-ray diffraction electron backscattering diffraction, transmission electron microscopy, three-dimensional atom probe technique, and high-energy X-ray diffraction (HEXRD). The results reveal that the tensile strength and electrical conductivity of the alloy are 937.27 MPa and 45.57% IACS, respectively, and that it has good stress relaxation resistance. There are many dislocation tangles, dislocation lines, dislocation cells, and deformation twins in alloys processed by cyclic cryogenic rolling and low-temperature aging. The alloy contains both 300–600 nm coarse particle precipitates and 5–10 nm rod-like nano-precipitated phases composed of (Ni, Co)2Si. The average dislocation density is (35.967 ± 1.513) × 10¹⁴ m⁻², and the twin stacking-fault probability is 14.414 ± 0.333 × 10⁻³ in the alloy aged at 350 °C for 2 h.
The discontinuous precipitation (DP) was known to mechanically detrimental mechanism compared to normal precipitation (continuous precipitation, CP), while the DP has the higher conductivity because of low solute content in matrix. To get the optimum balance of strength and conductivity, the bimodal-structured Cu-4Ni-1Si alloy composed of two regions with CPs and DPs was fabricated. Bimodal-structured alloy occupied by 50% of each region shows remarkable high strength and conductivity combination (1088 MPa / 38%IACS) beyond the expected values which summated in alloys with fully CP or DP. The accelerated strengthening of bimodal-structured alloy is caused by uni-directional alignment and enhanced plastic deformation of DPs in alloy after cold-working.
High strength and high conductivity (HSHC) Cu alloys are widely used in many fields, such as high-speed electric railway contact wires and integrated circuit lead frames. Pure Cu is well known to have excellent electrical conductivity but rather low strength. The main concern of HSHC Cu alloys is how to strengthen the alloy efficiently. However, when the Cu alloys are strengthened by a certain method, their electrical conductivity will inevitably decrease to a certain extent. This review introduces the strengthening methods of HSHC Cu alloys. Then the research progress of some typical HSHC Cu alloys such as Cu-Cr-Zr, Cu-Ni-Si, Cu-Ag, Cu-Mg is reviewed according to different alloy systems. Finally, the development trend of HSHC Cu alloys is forecasted. It is pointed out that precipitation and micro-alloying are effective ways to improve the performance of HSHC Cu alloys. At the same time, the production of HSHC Cu alloys also needs to comply with the large-scale, low-cost development trend of industrialization in the future.
CuNiSi/Si3N4 is fabricated by using the stir casting method. Metal matrix composite developed is tested to study the adhesive wear behaviour on wear and friction apparatus under dry sliding state using Taguchi’s L27 orthogonal array. The process parameters were load (15,25,35N), sliding velocity (1,2,3m/s) and sliding distance (750,1250,1750m). In light of the outcomes, load applied is the most influencing variable on the wear loss abided by sliding distance and velocity. Scanning electron microscope analysis exposed serious delamination of specimen under high load and sliding distance. The developed copper composite can replace aluminium bearings, cylinder liners, radiators, connecters.
The trade-off between strength and ductility has been a dilemma in copper matrix composites. In this work, we introduce a way of strengthening copper matrix composites containing TiO2 nanoparticles with remarkable ductility. The Cu–8wt%TiO2 composites were fabricated using the powder metallurgy route with spark plasma sintering (SPS) for different holding times incorporating hot extrusion. The sintered composites for longer holding times showed an inhomogeneous distribution of large dispersed particles located mostly along the grain boundaries. However, tensile strength was improved compared with pure copper while ductility was reduced. In contrast, after hot extrusion, a homogeneous distribution of reinforcement particles and grain refinement concurrently triggered strong strengthening and enhanced ductility. The contribution of synergistic strengthening mechanisms, i.e. Hall–Petch strengthening, Orowan pinning, dislocation density and load transfer effect, was studied and the key strengthening mechanisms were elucidated. It was found that composite yielding was strongly affected by sintering time, particulate size and interparticle spacing so that [email protected] composite presented the excellent yield strength of 290 MPa, about 72% above pure copper.
The aim of this work was to study the microstructure and functional properties of CuNi2Si1 alloy. The material was prepared classically by melting, casting, hot rolling and cold rolling. The obtained strips were processed with combined operations of supersaturation, ageing and one of the intensive deformation method – repetitive corrugation and straightening. The efficiency of RCS operation in shaping of functional properties in precipitation hardened copper alloys depends not only on tool geometry and operating parameters but also on whether and at what stage of strip production the supersaturation operation was applied. Application of the supersaturation before RCS operation broadens the potential to shape the set of functional properties. Comparable functional properties of the precipitation hardened copper alloy strips can be reached without application of the supersaturation operation in their manufacturing processes. The process of RCS applied after annealing, and the potentially slightly lower mechanical properties would be compensated by higher electrical conductivity.