Effect Of Co Content Research Articles

Effect of Co content on microstructure and properties of TiCN-TiB2 cermets prepared by spark plasma sintering from a TiCN-B4C-Ti-Co system

Series of TiCN-TiB2 cermets were in situ prepared from the TiCN-B4C-Ti-Co system via spark plasma sintering (SPS). The effects of Co content on the densification, microstructure, mechanical properties, and wear resistance of TiCN-TiB2 cermets were investigated. The results showed that the Co addition had little effect on the phase composition of the sintered cermets, but had significant influences on the densification, microstructure and mechanical properties. Appropriate addition of metal Co could enhance densification and promote the grain growth of ceramic phases, but excessive addition resulted in a decrease in hardness and wear resistance. When the Co content was 10 wt.%, the cermet obtained the optimal comprehensive performance (a hardness of 1757 HV and a fracture toughness of 7.02 MPa•m1/2). Meanwhile, the cermets with 10 wt.% Co addition exhibited optimum wear resistance properties due to a good combination of hardness and toughness and moderate grain size. In addition, the formation process and strengthening mechanism in present system were discussed in detail. Results from this work could provide valuable references for the fabrication of TiB2 reinforced TiCN-based cermets.

The effect of CO content on CH4/CO/H2 rotating detonation wave propagation characteristics

Rotating detonation experiments were conducted using CH4/CO/H2 (methane/carbon monoxide/hydrogen) mixtures with varying CO contents, the modes of rotating detonation wave (RDW) propagation in the mixtures were analyzed, and the impact of CO content on the propagation characteristics of the RDW in the gas mixture was compared. Three propagation modes of RDW were observed: sawtooth wave mode, mixed mode, and single wave mode. An increase in the CO content resulted in an upward shift in the range of working equivalence ratios for different gas mixtures. Additionally, the propagation modes of the same gas mixture change with increased fuel flow rate. When the equivalence ratio is below 1.13, it is observed that the gas mixture with the lowest CO content exhibits the highest RDW velocity and the shortest time required to establish RDW. This was attributed to the higher content of oxygen-containing functional groups, such as OH (hydroxyl), HO2 (peroxyhydroxyl), and O (oxygen atom), which were present under lean combustion conditions, along with the highest mass content of H2 in the gas mixture with the lowest CO content. Conversely, for equivalence ratios above 1.13, it is observed that the gas mixture with the highest CO content exhibits the highest propagation velocity and the shortest time required to establish RDW. This was attributed to the lowest mass content of CH4 and H2 in the gas mixture with the highest CO content at the same equivalence ratio, along with the inhibitory effect of elevated CO content on CH4 consumption under fuel-rich combustion conditions. The increase in the CO content resulted in maximum propagation velocities of the detonation wave being achieved for the three gas mixtures at equivalence ratios of 0.91, 1.09, and 1.19, with corresponding velocities of 1136.7, 1108.7, and 1113.2 m/s, and the shortest times required to establish RDW were measured at 1.5, 1.1, and 0.8 ms for the respective mixtures.

Effect of Co content on precipitation behavior of γ′ phase strengthened CoNi-based alloys

The CoNi-based alloys with nano-precipitates exhibit significant advantages in high-temperature applications due to their excellent thermal stability. This study investigates the influence of Co content (0 at%, 22.5 at%, 45.0 at%) on the morphological evolution, coarsening kinetics of γ' phases, and γ/γ' lattice misfit. The results reveal that the γ/γ' lattice misfit increases with increasing Co content. The addition of Co not only increases the number density of γ' phases but also effectively suppresses the coarsening of precipitates. Moreover, the coarsening rate constant of the γ' phase decreases with increasing Co content, with the alloy containing 45.0 at% Co exhibiting the lowest coarsening rate at 1.04 × 10−28 m3/s. Additionally, the increase in Co content enhances the hardness of the alloy, primarily due to the increased volume fraction of the γ' phase. This study contributes to understanding the mechanism of Co content variation on the characteristics and thermal stability of precipitates, providing support for the design of CoNi-based alloys.

Effect of cobalt content on the microstructure, microtexture, and mechanical properties of W-Ni-Fe-xCo alloys during solid-phase-sintering and liquid-phase-sintering

Compared the effect of Co content on the microstructure, microtexture, and mechanical properties of W-Ni-Fe-xCo alloys during solid-phase-sintering and liquid-phase-sintering. The results indicated there is a non-uniform distribution of W and γ phases, accompanied by the presence of little voids during solid-phase-sintering at 1420 °C. Adding Co element enhances the wetting between the W and γ phases, and reduces the liquid-phase-sintering temperature, shrinking the size and quantity of pores. The W phase transforms into ball-shaped particles with completed liquid-phase-sintering at 1440 °C. With increased Co content, W grain size decreases, matrix fraction volume increases, and Cw-w continuity and dihedral angle decrease. The mechanical properties of the alloys improve with sintering temperature and Co content, the tensile strength and elongation reached 989 MPa and 13.7% due to the elimination of holes and the W content increased within γ phase. The relationship among W content in γ phase, strength, elongation, and microhardness with Co content were revealed. The solution strengthening effect increases, which drives the co-deformation of W and γ phases, thereby increasing the strength and elongation. The addition of Co element and the atomic diffusion at high temperature made the fibre microtexture more concentrated.

Effect of Co content on electrochemical hydrogen kinetics properties of single-phase BCC-type MgAlTiCoxNi high entropy alloys used as a negative electrode in basic and acidic electrolyte

In this report, the effect of Co content on the electrochemical hydrogen storage reaction kinetic of MgAlTiCoxNi (x = 1, 1.5 and 2) High Entropy Alloys (HEAs) as negative electrodes under basic (6 M KOH) and acidic (1 M H2SO4) electrolyte was studied. Empirical thermodynamic parameters were used to predict the formation of HEAs. The alloys were obtained after 8 h of high-energy ball-milling. The structural analysis showed the formation of a BCC structure and a reduction of the unit lattice with increasing Co content. At high temperatures, the structure changes from BCC-type to B2-type. The morphology and surface area of the MgAlTiCoNi, MgAlTiCo1.5Ni, and MgAlTiCo2Ni alloy powders are very similar. Electrochemical measurements show that alloys exposed to acidic solutions as negative electrodes exhibit higher discharge capacity and better electrochemical hydrogen storage kinetics properties. The increase in Co content in the alloys in both basic and acidic solutions reduced the discharge capacity. Furthermore, a high Co content in the electrodes exposed to an acidic electrolyte reduces the anticorrosion properties of the alloy. The MgAlTiCoNi HEA electrode achieved the best electrochemical performance with a discharge capacity of 465 mAh/g in an acidic electrolyte after a short galvanic charge (60 min). The concentration of Co in the HEAs revealed a direct relationship with the hydrogen diffusion rate, while the lattice parameter is associated with the discharge capacity.

Effect of Co Contents on Microstructure and Cavitation Erosion Resistance of NiTiAlCrCoxN Films

Effect of Co Contents on Microstructure and Cavitation Erosion Resistance of NiTiAlCrCoxN Films

Corrosion Behavior of As-Cast and Heat-Treated Al-Co Alloys in 3.5 wt% NaCl.

The present work evaluates the effect of Co content on the microstructure and corrosion performance of Al-Co alloys of various compositions (2-32 wt% Co), fabricated by flux-assisted stir casting. A preliminary investigation on the effect of heat treatment (600 °C, up to 72 h) on the microstructure and corrosion behavior of Al-20 wt% Co and Al-32 wt% Co was also conducted. The Al- (2-10) wt% Co alloys were composed of acicular Al9Co2 particles uniformly dispersed in an Al matrix. The Al-20 wt% Co and Al-32 wt% Co alloys additionally contained Al13Co4 blades enveloped in Al9Co2 wedges. Heat treatment of Al-20 wt% Co and Al-32 wt% Co led to a significant reduction in the volume fraction of Al13Co4 and a decrease in hardness. Al-Co alloys with high Co content (10-32 wt% Co) exhibited greater resistance to localized corrosion in 3.5 wt% NaCl, but lower resistance to general corrosion compared to the (0-5 wt% Co) alloys. Heat treatment led to a slight increase in the corrosion resistance of the Al-Co alloys. The microstructure of the produced alloys was analyzed and correlated with the corrosion performance. Finally, corrosion mechanisms were formulated.

Effect of co on mechanical and electrochemical properties of powder synthesized cellular Ti-Al alloy

ABSTRACT This work describes the effect of Co content on the compressive and electrochemical behaviour of cellular Ti4AlxCo (x = 2%, 4%, 6% and 8 wt%) alloy. Cellular products were prepared through powder metallurgy route by adding 70 v% of ammonium bicarbonate as space holder in Ti4AlxCo powder mixture. Relative density of the final products slightly upsurged due to increment of Co amount and it was found in the range of 0.32–0.35. Microstructure represented the interconnecting pores which will be advantageous to circulate the body fluid, if used as a bone implant. Plastic collapse stress of Ti4Al8Co was about 45% higher than Ti4Al2Co. Also, the elastic modulus was under the range of modulus of natural bone (11 ± 1 GPa). In Tafel plot, value of corrosion current density shifted from 8 μA/cm2 to 15 μA/cm2 by increasing the Co content from 2 wt% to 8 wt% which indicates the hampering of corrosion resistance. Corrosion rate followed the linear relationship with Co content. Best fitted electrochemical circuit showed the double layer oxide formation during corrosion. Micrographs of corroded cellular samples also represent that the surface of material is more prone to corrosion containing higher amount of Co.

Effect of Co content on microstructure and mechanical properties of maraging steel

Effect of Co element on the microstructure and mechanical properties of maraging steel is studied and summarized. The microstructure and mechanical properties of five different compositions of maraging steels were characterized and tested in three heat treatment states, with the heat treatment schemes of homogenization treatment at 1300 °C × 10h, solution treatment at 800 °C × 2h, and aging treatment at 480 °C × 5h. The research has discovered that increasing the Co content in three different heat treatment states can lead to a reduction in the size of the original austenite grains and the width of martensite laths. In the aged state, higher Co content causes the precipitation phase to transform from an ellipsoidal Mo-rich phase to a needle-like Ni3(Mo, Ti) phase. These changes in the size, shape, and density of the precipitated phases result in a more pronounced effect of precipitation strengthening, leading to a significant increase in the material's strength.

Correlation between stress relaxation induced anisotropy, magnetic domain, and permeability of Co-doped FeCuSiBNbMn alloys

The effect of Co contents on the permeability, magnetic anisotropy, and structure has been investigated for FeSiBNbCuMn amorphous alloys during annealing with and without tensile stress. Large stress relaxation-induced anisotropy (Ku) of 482.0–1485.4 J/m3 is observed with an easy axis perpendicular to the direction of tensile stress (i.e., ribbon axis), which results in constant permeability of 1–2.8 × 103 at 1 kHz − 1 MHz. Different from the irregular domain structure in the samples annealed without tensile stress, stress annealing generates regular domains and 180° straight walls, and domain width increases with the increases of Co contents. Besides, the correlation between permeability, induced anisotropy, and domain width is established. These results could provide a good guide for improving the frequency stability of permeability by adjusting anisotropy and domain structure.

Effect of Co content on mechanical properties of laser cladded WC coatings: Insights from first-principle calculation and machine learning

Effect of Co content on mechanical properties of laser cladded WC coatings: Insights from first-principle calculation and machine learning

Effect of Co content on the microstructure, mechanical properties and corrosion behavior of Zr alloys

The microstructure, mechanical properties and corrosion properties of Zr-xCo (x = 0, 2, 4, 6, 8, 10 at.%) binary alloys have been systematically studied. The microstructure of the alloy was analyzed by optical microscope, X-ray diffractometer, scanning electron microscope, transmission electron microscope and electron probe, and the existence of Zr3Co phase was found. The mechanical properties of the alloy were analyzed by compressive stress-strain test and Vickers hardness test. It was found that the addition of Co improved the strength of the alloy, and the ductility of the alloy was the best when the content of Co reached 6 at.%. Through electrochemical experiments, the corrosion properties of the alloy were analyzed, and it was found that the addition of Co had an active influence on the corrosion resistance of the alloy, which made the passivation film formed by the sample denser, and effectively alleviated the corrosion behavior of the alloy. Surface potential analysis was performed with atomic force microscope. Through X-ray photoelectron spectroscopy analysis of passive film, it is revealed that passive film mainly consists of ZrO2, Co3O4, Co(OH)2 and Zr2O3.

Effect of Co Content on the Microstructure and Corrosion Behavior of Al0.3CoxCrFeNi High Entropy Alloys

Effect of Co Content on the Microstructure and Corrosion Behavior of Al0.3CoxCrFeNi High Entropy Alloys

Ductile Ni-based bulk metallic glasses at room temperature

In this work, a series of new Ni76-xCoxNb4P16B4 (x = 5, 10, 15, in at.%) bulk metallic glasses (BMGs) with the maximum diameter in the range of 1.2–1.6 mm were prepared by combining fluxing and J-quenching technology. The effects of Co content on glass forming ability (GFA), thermal stability, mechanical properties, serrated-flow behaviors and corrosion performance of the present Ni-based BMGs were systematically investigated. The ranges of Tg and ΔTx are 664–668 K and 21–31 K, respectively. Uniaxial compressive tests revealed that the present Ni-based BMGs have the compressive plastic strain (εp), yield strength (δy), and fracture strength (δf) that range from 16% to 27%, 2.1–2.6 GPa, and 2.2–3.6 GPa, respectively. The unprecedented mechanical properties originate from more icosahedral-like clusters (ILCs) and crystal-like clusters (CLCs) in the present Ni-based BMGs. It is found that the serrated-flow behaviors of the present Ni-based BMGs transition self-organized critical state (SOCs) into chaotic state (Cs) as plasticity decreases. The stick-slip dynamics were used to calculate the average shear-band velocity (ASBV), which shows an increasing trend as the Co content rises from 5 at.% to 15 at.%. Electrochemical measurements in 3.5 wt.% NaCl solution showed that the Ni71Co5Nb4P16B4 BMG has a self-corrosion current density of 3.30 × 10−8 A/cm2 and significantly stronger corrosion resistance than austenite 316L and 304L stainless steel. The present Ni-based BMGs have excellent comprehensive performance, which has great potential for industrial applications.

Effect of Si/Al addition on magnetic properties of Fe-Co alloy

Fe-Co alloys are promising materials for high power density motors, since they have higher Bs than Fe-Si steels which are most commonly used as the motor cores. It is known, however, that the Fe-Co alloys generally have poor workability due to an existence of the brittle phase, ordered B2. In this study, effects of Co content and Si/Al addition with the Fe-Co alloys on the workability and magnetic properties were investigated. The neutron diffraction measurements of the Fe-Co alloys with different Co contents of 5, 18, 27, and 49 mass% were first conducted to know the existence of the ordered B2 phase. The result showed that the B2 phase was observed in the Fe-Co alloys with Co contents of 27 and 49 mass%, while the alloys with 5 and 18 mass% did not contain it, which suggests the latter two alloys have the better workability. Then, we checked the effect of Si/Al addition on the magnetic properties of the 82Fe-18Co alloy, and found that the co-addition of Si/Al reduce the coercivity, Hc to about 60 A/m and iron loss to less than 170 W/kg while maintaining a high B value at 30 000 A/m above 2.2 T.

Effect of Co Content and Microcracks on Laser Shock Resistance of WC Nozzle

Effect of Co Content and Microcracks on Laser Shock Resistance of WC Nozzle

Effects of Co on microstructure evolution of a 4th generation nickel-based single crystal superalloys

For further composition optimization, the microstructure evolution of the fourth-generation nickel-based single crystal superalloys, which contains different Co (Cobalt) additions, is studied at three thermal exposure temperatures. Based on Lifshitz, Slyozov and Wagnerz (LSW) theory and trans-interface diffusion-controlled (TIDC) theory, the effects of Co content and aging temperatures on coarsening rate of γ′ phase are investigated in detail. The results show that the diffusion coefficient of solute is accelerated, but the γ/γ′ interfacial energy decreases with the addition of Co, thus changing the coarsening rate. Furthermore, the thermodynamic equilibrium solubility difference of elements between γ′ and γ, and the segregation of elements at the γ/γ′ interface are alleviated with increase of Co, resulting in the suppression of TCP phase after long-time thermal exposure, which guides the economical design of nickel-based single crystal superalloys.

Twinning damping interface design and synergistic internal friction behavior in FeMnCrCo high-entropy alloys

Vibration and noise reduction has always been important problem to be solved in the fields of rail transit, aerospace, marine engineering, and so on. In this paper, a novel Fe65-XMn20Cr15CoX (X = 5, 10, 15, 20) dual-phase high-entropy damping alloy with excellent properties were prepared by vacuum melting. The dependence of the alloy damping behavior on the twin interface, magnetic properties and phase interface was emphatically analysed. The effects of Co content on its microstructure, damping behavior and magnetic properties were investigated. The results show that with the increase of Co content, ε martensite gradually transforms to γ austenite, and the number of twins increases gradually. The peak damping (Q−1) increased from 0.0442 to 0.0595, an increase of 34.6%. The coupled effects of magneto-mechanical hysteresis, twin interface motion, and phase interface motion provide the alloy's excellent damping properties. The alloy has a higher damping internal friction peak of around 200 °C, which is due to the phase transition from ε to γ at the temperature. By adjusting the Co content, the phase content and twinning and other microstructures of the alloy can be regulated, and multiple damping mechanisms can be coupled to achieve higher damping performance.

The Effect of Co Content and Annealing Temperatures on the Resistivity in Ag-Co Films.

Ag-Co films with ultra-high resistivity were prepared on polyimide by magnetron sputtering. The effect of Co content and annealing temperatures on the resistivity and microstructure of Ag-Co films has been thoroughly investigated and the relation between resistivity and microstructure has been discussed. Results show that thicker Ag-Co films without annealing present lower resistivity due to better crystallinity. However, thin Ag-Co films (≤21 nm) annealed at 360 °C present ultra-high film resistivity because of the formation of diffusion pits on the film surface which blocks the transmission of electrons in films to increase film resistivity. Inversely, the resistivity of thick Ag-Co films (≥45 nm) annealed at 360 °C is much less than that annealed at lower than 260 °C owing to no diffusion pits. Furthermore, the addition of Co inhibits the growth of Ag grains and limits the migration of electrons in Ag-Co films further, also resulting in the increase of Ag-Co films’ resistivity.

Atomistic insights on the deformation mechanisms of Cox(CrNi)100-x multicomponent alloys: The effect of Co content

CoCrNi multicomponent alloys with equiatomic and non-equiatomic concentrations are promising for achieving an excellent balance of strength and ductility. However, the correlations between elemental concentrations and deformation mechanisms of this alloy family need to be uncovered for further targeted alloy design. In this work, atomistic molecular dynamics simulations were performed to study the effects of Co concentration on the mechanical behaviors and underlying deformation mechanisms of single-crystal Cox(CrNi)100-x (x = 13, 23, 33.3, 50 at. %) alloys. Atomic-scale microstructural evolution with increasing the compressive strain was revealed in each specimen with different Co concentrations. The results suggest that the yield stress and elastic modulus are enhanced with increasing the Co content. Atomic pairs containing Cr exhibit the lowest cohesion energy among all pair types, and therefore Cr atoms participate most actively in dislocation nucleation. Although dislocation slip comes into play in all specimens, the primary deformation mechanism changes from the multilayering of stacking faults (SFs) to the formation of primary-secondary twin pairs with the increase of Co content. Further, the twinnability of these alloys was estimated using a theoretical model based on the generalized stacking fault energy (GSFE) curves. The results indicate that the Co50Cr25Ni25 alloy owns the highest twinning tendency among the probed alloy variants, which promotes the formation of secondary deformation twins and leads to high deformability. This work provides guidelines for the design of non-equiatomic CoCrNi multicomponent alloys with proper Co content for desirable mechanical properties.