Reinforced Iron Matrix Composites Research Articles

Preparation and formation mechanism of (W) WC/Fe bundle reinforced iron matrix composites

To address the issue of strength and toughness inversion in traditional metal matrix composites, which are reinforced by uniformly distributed ceramic particles, this research developed a novel space bundle configuration of reinforced iron matrix composite using tungsten wire (W) and tungsten carbide (WC). This composite was prepared using a lost foam casting process combined with in-situ reaction. Microstructural analysis revealed that WC particles are distributed along the tungsten wire, with larger particles at the center and smaller ones at the edges. The formation of the reinforcement occurs in two stages: first, a solid-liquid reaction between the solid tungsten wire and molten iron during the lost foam casting process, promoting WC formation at high temperatures and carbon potential; second, an in situ solid-solid reaction where Fe diffuses and Fe3W3C decomposes, forming a composite structure of WC and α-Fe. The composite obtained at 1100 °C for 9 h exhibited a compressive strength of 836.59 MPa and a fracture strain of 18.69 %, representing increases of 48.46 % and 48.69 % respectively compared to gray cast iron (GCI). The (W) WC/Fe bundle reinforcement effectively enhances the strength and toughness of the composite through the high volume fraction and gradient distribution of WC particles, combined with the synergistic effect of α-Fe. This research provides a new strategy for improving the mechanical properties of composite materials and resolving the issue of strength-toughness inversion.

Effect of temperature on the microstructure and mechanical properties of TiC/Fe matrix composites fabricated by spark plasma sintering

The effects of sintering temperatures on the microstructures and mechanical properties of titanium carbide particles reinforced iron matrix composites (TiC/Fe MCs) fabricated by the spark plasma sintering (SPS) process with pure element powders have been systematically investigated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron back scattering diffractometer (EBSD), and energy dispersive spectroscopy (EDS) have been conducted for microstructural analysis. The results show that with increasing sintering temperatures, the porosity of the composites initially decreases and then increases. Simultaneously, the grain size gradually diminishes while element diffusion becomes more uniform. Upon reaching a critical sintering temperature (1120 °C), the original grain size disappears and carbides undergo decomposition and reprecipitation to reach an equilibrium state, with which optimal comprehensive properties can be achieved (porosity decreases to a minimum of 3.85%, grain size of 2.69 μm, Vickers hardness reaches 595 HV0.5, bending strength is at 662 MPa, coefficient of friction is at 0.74, and wear loss to 0.21 mg). These property enhancements have been attributed to reduced porosity in the composites, decreased grain size, and improved anchoring effect of carbides within the matrix. Additionally, the primary fracture mechanisms and wear mechanisms of TiC/Fe MCs with different process parameters have been analyzed. When the temperature is below 1080 °C, intergranular fracture predominates, whereas transgranular and ductile fractures become predominant above this threshold. When the temperature is below 1120 °C, fatigue wear, oxidation wear, and abrasive wear are predominantly observed. Conversely, when the temperature exceeds 1120 °C, oxidation wear and abrasive wear become the primary mechanisms.

Formation mechanism of interface layer of ZTA particle reinforced iron matrix composite

ZTA particle modified by Ti–Ni powder(Ti–Ni@ZTAp) reinforced iron matrix composite (Ti–Ni@ZTAp-VCp/Fe45) was fabricated by powder metallurgy. The microstructure, scratch properties and formation mechanism of the interface were investigated. An interface layer of 10 μm–20 μm was formed between ZTAp and VCp/Fe45 matrix, which reduced the defects at the interface and played a good transition role. The phases in the interface layer were TiO, Ti6O11 and ZrO2. Metallized layer was formed on the surface of ZTAp after the vacuum sintering of Ti–Ni powder modified ZTAp at 1500 °C. Elemental diffusion occurred between the Ti–Ni powder and ZTAp, which resulted that the ZrO2 phase migrated from ZTAp to the coating layer and reacted with the Ti–Ni powder to form new phases of Ni3Ti, TiO and Ti6O11. The models of the formation mechanisms of the metallized layer, interface layer between ZTAp and VCp/Fe45 matrix were established. Ni3Ti in the metallized layer on the surface of ZTAp was further decomposed duing the vacuum sintering of Ti–Ni@ZTAp-VCp/Fe45 composite, and then the elements Ni and Ti diffused with elements Fe, Cr and V of the VCp/Fe45 matrix. The V element diffusing to the interface layer can further displaced the Ti element in ZTAp and realized the diffusion from iron matrix to ZTAp. The metallized layer on the surface of ZTAp was transformed into an interface layer between ZTAp and VCp/Fe45.

Microstructural evolution and performance analysis of WC-11Co reinforced iron matrix composites

This paper presents a new fabrication method utilizing lost foam casting as a processing technique to synthesize high-strength and ultra-wear-resistant particle reinforced iron matrix composites. The composite material incorporates large-sized WC-11Co reinforcement. The composite exhibits a multiphase microstructure composed of WC-11Co, α-Fe, and carbide precipitates that extend at different length scales. The precipitation of large-sized M3W3C (M = Fe, Co) type carbides at the WC-11Co/matrix interface is well controlled. A favorable reaction layer is formed between WC-11Co and the matrix. Nano-precipitates are pinned within the reaction layer, exhibiting a high degree of coherence with the iron matrix. The stress field at the interface is complex due to thermal stress, phase transformation stress, and microstress. The stress state between WC-11Co and the matrix consists of compressive residual stress-tensile residual stress-compressive residual stress, with compressive residual stress far exceeding tensile residual stress. The WC-11Co/Fe0.35C5CrMn composite exhibits outstanding compressive strength of 2.18 GPa and a fracture strain of approximately 24.6 %. Moreover, the composite demonstrates excellent wear resistance, with a threefold improvement compared to the matrix under severe wear conditions. The following mechanisms contribute to the enhanced mechanical properties: multiphase material system, coherent multiscale interfaces, grain refinement, dislocation strengthening, and residual stress strengthening.

WC-18Co reinforced Iron matrix composites: Microstructure and interface characteristics

Particle reinforced iron matrix composites have gained considerable attention as advanced structural materials. In this study, large-sized WC-18Co reinforced iron matrix composites were prepared using the casting infiltration method. We investigated the microstructure and interface characteristics of WC-18Co/FMC, analyzed the stress state at the interface, and tested the mechanical and tribological properties of the composite material. The research findings reveal that WC-18Co/FMC is a multiphase system composed of WC, M3W3C (M = Fe, Co), and precipitates. The strong interface reaction results in the formation of a thick transition layer between WC-18Co and the matrix. Grain refinement occurs around the reinforcing particles. During solidification, the difference in thermal expansion coefficients between WC-18Co and FMC induces thermal stress, leading to compressive residual stress on both sides of the interface. The compressive stress state inhibits crack initiation and propagation, enhancing the bonding strength. Alternating stresses at the interface enhance dislocation motion, grain slip, and twinning phenomena in the transition layer. Nanoscale compounds embedded in the transition layer impede dislocation slip, resulting in dislocation entanglement and pile-up. WC-18Co/FMC exhibits a 60.66% increase in hardness compared to FMC. Under impact energies of 1 J, 3 J, and 5 J, the wear resistance improves by factors of 2.985, 2.358, and 2.072, respectively. The significant improvement in the composite material's performance is attributed to strengthening mechanisms such as the multiphase system, grain refinement, nanoscale precipitates, and residual stress strengthening.

Research and prospect of particle reinforced iron matrix composites

Research and prospect of particle reinforced iron matrix composites

Effect of strength and toughness of ceramic particles on impact abrasive wear resistance of iron matrix composites

The wear resistance of ceramic particle reinforced metal matrix composites is closely related to the properties of ceramic particles. In this study, three kinds of ceramic particle (with 30 % volume fraction) reinforced iron matrix composites (Al2O3/Fe45, ZTA(Zirconia toughened alumina ceramic particles)/Fe45 and ZrO2/Fe45) were prepared by powder metallurgy method. The mechanical properties, impact abrasive wear resistance and impact abrasive wear mechanism of the composites were studied, and the phase transformation of ceramic particles in the composites was analyzed. The results show that the elastic modulus and hardness of ZTA/Fe45 composite are between Al2O3/Fe45 and ZrO2/Fe45, which are 248.5 GPa and 13.3 GPa, respectively. The ZTA/Fe45 composites exhibit a better impact wear resistance than the other two composites. The impact abrasive wear resistance of the three kinds of composites is positively correlated with the product value of fracture toughness and hardness (H·KIC) of ceramic particles. The wear mechanism of the Fe45 matrix of the composite is micro-furrow and plastic deformation. The brittle fracture and spalling of Al2O3 ceramic particles occur after impact abrasive wear, forming spalling pits and accelerating the wear of Al2O3/Fe45 composites. ZrO2 ceramic particles lead to easy removal from the Fe45 matrix due to lower hardness after impact abrasive wear. ZTA ceramic particles protruded from the surface of the Fe45 matrix after impact abrasive wear. On the surface of ZTA particle, the irregular protuberant steps morphology are formed by SiO2 abrasive impact and tangential wear. The ZTA and ZrO2 ceramic particles in the worn surfaces of the composites undergo t-ZrO2 to m-ZrO2 phase transformation during the impact wear, and the t→m phase transformation content is related to the impact energy. The amount of phase transition increases with the increase of impact energy, When the impact energy is higher than 2J, the amount of phase transition tends to be stable. Under the same impact energy, the amount of t→m phase transition in ZrO2 particles is much lower than that in ZTA. The t→m phase transformation increases the toughness of ZTA particle，improving the impact abrasive wear resistance of ZTA/Fe45 composite.

WC-reinforced iron matrix composites fabricated by wire arc additive manufacturing combined with gravity-driven powder feeding: particle transportation and size effects

Purpose A new wire arc additive manufacturing (WAAM) process combined with gravity-driven powder feeding was developed to fabricate components of tungsten carbide (WC)-reinforced iron matrix composites. The purpose of this study was to investigate the particle transportation mechanism during deposition and determine the effects of WC particle size on the microstructure and properties of the so-fabricated component. Design/methodology/approach Thin-walled samples were deposited by the new WAAM using two WC particles of different sizes. A series of in-depth investigations were conducted to reveal the differences in the macro morphology, microstructure, tensile performance and wear properties. Findings The results showed that inward convection and gravity were the main factors affecting WC transportation in the molten pool. Large WC particles have higher ability than small particles to penetrate into the molten pool and survive severe dissolution. Small WC particles were more likely to be completely dissolved around the top surface, forming a thicker region of reticulate (Fe, W)6C. Large WC particles can slow down the inward convection more, thereby leading to an increase in width and a decrease in the layer height of the weld bead. The mechanical properties and wear resistance significantly increased owing to reinforcement. Comparatively, samples with large WC particles showed inferior tensile properties owing to their higher susceptibility to cracks. Originality/value Fabricating metal matrix composites through the WAAM process is a novel concept that still requires further investigation. Apart from the self-designed gravity-driven powder feeding, the unique aspects of this study also include the revelation of the particle transportation mechanism of WC particles during deposition.

Study on cobalt coating on ZTA particles by electroless plating and impact-abrasive wear behavior of ZTAp reinforced iron matrix composite

The electroless cobalt plating modification of ZTAp (Zirconia toughened alumina particle) surface and the impact-abrasive wear behavior of ZTAp and NbCp(Niobium carbide particle) reinforced Fe60 matrix composites (ZTAp-NbCp/Fe60) were investigated. Cobalt was deposited on the ZTAp surface by electroless plating (modified ZTAp) to strengthen the interface bonding between ZTAp and matrix. Both composites reinforced with modified ZTAp and unmodified ZTAp were prepared through vacuum sintering, and their impact-abrasive wear performance testing under different impact energy were carried out with MLD-10 impact-abrasive wear tester. The results showed that the optimal conditions to coat cobalt on the ZTAp surface included of: initial pH value of plating solution was 9, the concentration of NaH2PO2.H2O, and C4H4Na2O6.2H2O was 0.25 mol/L and 0.8 mol/L respectively. The impact-abrasive wear-resistant performance of the modified ZTAp reinforced Fe60 matrix composite was significantly enhanced by more than 35% than the unmodified ZTAp reinforced composite under high energy impact condition. Cobalt and liquid iron had good wettability, and the interface strength significantly increased. During the sintering process, cobalt diffused at the interface, thus leading to a significant binding force between ZTAp and the iron matrix interface. This study suggested that the modified ZTAp could have a better and longer protective effect than unmodified ZTAp on the matrix.

Effect of sintering parameters on the microstructure and micromechanical properties of in-situ synthesized boride phases (Fe2B-FeB) in iron matrix composites reinforced with B4C particles

In this study, the influence of sintering parameters on the microstructure and micromechanical properties of ceramic reinforced iron matrix composites is investigated. Composites containing 5–10-20-30 vol% B 4 C were fabricated by in-situ powder metallurgy (IPM) and sintered at various temperatures and durations. Hot pressed powder mixtures were sintered at constant duration (60 min at 1000–1150-1300 °C) and constant temperature (1150 °C for 30–120 min) in a protective environment. The influence of these parameters is evaluated by investigating microstructural changes using SEM, XRD, EDX, and optical microscopy, density and porosity by Archimedes method, and finally, micromechanical properties by hardness determination. Results showed that while increasing reinforcement ratios of B 4 C particles caused reduced density in the green compacts, B 4 C particles under a certain size (<7 μm) were randomly distributed in the mixture and lead to the formation of iron borides. Additionally, increased hardness was witnessed for all temperatures with increasing reinforcement ratios until 20 vol% B 4 C, after which hardness was decreased. In fact, 20 vol% B 4 C showed excellent properties and was comparatively much sensitive to both, increasing sintering temperatures and duration. In-situ synthesized iron borides became the decisive factor in the increased hardness of the composites. • The properties of Fe-B 4 C composites were evaluated at various sintering parameters. • The iron boride phase was formed in different sizes and shapes as a result of the diffusion of boron from the B 4 C. • Composition of mixture powders and sintering time affected the dispersion of the boride phase. • The hardness of composites was significantly developed by in-situ synthesized boride phases. • Sintering time causes the phase formation in larger areas that enhanced the overall hardness.

Comparison of theoretical and experimental physio-mechanical properties of coal-fly ash (CFA) reinforced iron matrix composites

Comparison of theoretical and experimental physio-mechanical properties of coal-fly ash (CFA) reinforced iron matrix composites

Enhancing the strength-ductility synergy of Fe-based composites by changing interface bonding between matrix and TiCx with various stoichiometric ratios

The increase of strength in composites usually comes at the cost of ductility. This work proposed a strategy of design and synthesis of TiCx nanoparticles with controlled Ti/C stoichiometric ratios to adjust the microstructure and thus enhance the mechanical properties of the TiCx nanoparticles reinforced iron matrix composites. The changes of size and morphology of TiCx nanoparticles were investigated by self-propagating combustion synthesis (SHS) in the Fe–Ti–C reaction system. The influences of Ti/C stoichiometric ratios on the interface bonding and mechanical properties of Fe/TiCx were analyzed by lattice mismatch calculation. The results indicate that the morphology of TiCx nanoparticles changes from polyhedral to near-spherical sometimes accompanied by a few cubes with an increase in Ti/C stoichiometric ratios. The maximum yield strength (1525 MPa) compressive strength (2224 MPa) and microhardness (691.5 HV) of the TiCx/Fe composites are obtained when the C/Ti stoichiometric ratio reaches 1.0. The TiC0.8/Fe composites present a remarkable ductility up to 8.34%. Based on the lattice mismatch calculation, the good mechanical properties are mainly because the low lattice mismatch reduces the interfacial energy and thus leads to the higher mechanical properties. Effective design and control of the morphology of TiC particles and the interface bonding in Fe melt can maximize comprehensive performances and applications.

Interfacial bonding and abrasive wear behaviours of the iron matrix composites

Ceramic particles reinforced iron matrix composites attract considerable interest in the industrial engineering field due to the ceramic’s excellent fatigue and wear resistance. ZTA ceramic particle has been regarded as an ideal reinforcement phase. In this study, three-body abrasive wear behaviours and the mechanism of the ZTA/Fe composites and high chromium white cast iron Cr15 standard samples were investigated. The wear resistance of the ZTA/Fe composite was superior to the Cr15 standard sample under SiO2 abrasives. The extruded ZTA could protect the matrix surrounding ZTA ceramic particles. However, ZTA ceramic particles were cut together with the Cr15 matrix under SiC abrasives. The wear mechanism of the composites was a combination of the cutting and fatigue for SiC abrasives.

The effect of multi-arc ion plating NiCr coating on interface characterization of ZrO2–Al2O3 ceramics reinforced iron-based composites

The ZrO2–Al2O3 (ZTA) ceramic particles reinforced iron matrix composite was a novel wear-resistance material because of their excellent toughness and hardness. However, the poor interfacial bonding property restricted the application of ZTAP/Fe composites in the harsh service condition. A continuous and uniform Ni80Cr20 coating on the ZTA ceramic surface was successfully prepared by multi-arc ion plating. The influence of NiCr coating on the interfacial character of ZTAP/Fe composites was investigated. The interface characteristics and phase constitutions of ZTAP/Fe composites were also analyzed by electron probe microanalysis (EPMA) and transmission electron microscopy (TEM). The results showed that the Ni80Cr20 coating can significantly improve the interfacial layer bonding of composites without visible defects. The diffusion of Ni and Cr and the formation of a continuous transition layer ensure the metallurgical bonding between ZTA ceramic and iron matrix. The composite N1 acquired better wear resistance than that of composite N2 without Ni80Cr20 coating, and the relative wear resistance was 1.98 times at the 55 N applied load. The interface of composite N1 was closely bonded with a transition layer, which may prevent the ceramic particles peeling off from the iron matrix during the wear process.

The investigation on the fabrication and microstructure of a novel core-shell structure reinforced iron matrix composite

To make the steel/iron composites with better comprehensive mechanical properties, a novel iron matrix composite reinforced with three-dimensional core-shell structure (CS) reinforcing particulates is designed and fabricated via powder hot-pressing sintering process. Studies have shown that the CS consists of isolated soft W core and dense hard shell, that is, showing the structural characteristics of “inner soft and outer hard”. When the carbon content of the raw material powder Fe–W–C ternary system is 0, 0.5, 1.0, 1.5 and 2.0 wt%, the CS of W@(Fe7W6 + Fe2W), W@Fe3W3C, W@(W2C + WC + Fe3W3C)Ⅰ, W@(W2C + WC + Fe3W3C)Ⅱ, and W@(W2C + WC + Fe3W3C)Ⅲ is formed in the matrix, respectively. The formation of CSs with different characteristics is mainly due to the diffusion of Fe atoms and/or C atoms into the W lattice to undergo a diffusion-type solid state phase transformation to form corresponding compounds and the formation kinetics of different phases determined by different carbon concentrations. Furthermore, the results of nanoindentation and Vickers indentation show that the hardness of the shell layer is much greater than that of the metal W core and matrix, but its plastic deformation rate is much smaller than that of the metal W core and matrix. The metal W core and the iron matrix can significantly inhibit the length of the crack propagation, thereby improving the toughness of the composite. And the hard shell layer with high volume fraction can significantly improve the strength of the composite. Therefore, the iron matrix composite reinforced with three-dimensional CS reinforcing particulates is expected to obtain good toughness and excellent strength, and this work may provide a new strategy for the structural design of steel/iron materials.

Effects of active elements on adhesion of the Al2O3/Fe interface: A first principles calculation

The poor wettability of alumina surface greatly limits the interface binding between alumina and iron in alumina reinforced iron matrix composites. In this work, the active elements (Ti and Ni) additives are introduced into the interface to enhance the adhesion of the interface, and the activation mechanism is studied. Through the analysis of the embedding ability of activating elements Ti or Ni in Al2O3/Fe interface and their influence on adhesion of interfaces, it is revealed that Ti is prone to segregation at the interface and has a great improvement on the strength and stability of interface binding. However, Ni hardly enhances interface interaction and even causes interface deterioration. Electron structures analysis shows that 4 s, 3p, 3d coupling of Ti results in more electrons involved in the interface interaction, and the formation of Ti-Fe and Ti-O bonds essentially determines the increase of the work of adhesion. The activation mechanism of Ti and Ni well explains the experimentally reported different existence forms and action modes of Ti and Ni.

Microstructure evolution and in-situ-formed mechanism of dual-scale WC-Fe reinforced iron matrix composites

Dual-scale WC–Fe reinforced iron matrix composites were prepared by hot pressing sintering under a pressure of 10 MPa at 1250 ± 5 °C for 6, 10, and 14 h using low-cost ferrotungsten, graphite, and Fe powders as raw materials. The microstructure and in-situ-formed mechanism of composites were studied by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The mixed powders with ferrotungsten and graphite comprised W, Fe2W, Fe7W6, and Gr, which showed agglomeration after 48 h milling. When the hot pressing sintering time was prolonged from 6 h to 14 h, the W2C and Fe3W3C phases emerged as intermediate phases. The main composite phases included WC and α-Fe, where dual-scale WC-Fe reinforcements were distributed uniformly within the α-iron matrix. The average size of irregularly shaped WC particles in WC–Fe reinforcements totaled 5 μm, and the volume fraction of WC reached 76.40%. The amount of local liquid phase decreased with decreasing carbon content, improving the capillary driving force and promoting the Fe3W3C formation. Finally, sufficient carbon content ensured that the intermediate phases W2C and Fe3W3C transferred to WC completely.

Effects of manganese on diffusion and wear behavior of ZTA particles reinforced iron matrix composites in vacuum

Different volume fraction ZTA particles reinforced high chromium cast iron (HCCI) matrix composites were fabricated by liquid phase sintering (LPS) in vacuum of −0.1 atmospheric pressure. The influence of manganese on the microstructure, phase constituents and mechanical properties of the ZTA particles reinforced HCCI composites was investigated by means of SEM, XRD, and nanoindentation tests. The results demonstrated that the interfacial layer with a thickness of 25–35 μm was formed between ZTA particles and HCCI matrix, combined the effects of manganese additions. The elements in the interfaces layer are mainly Mn, Si, Zr and Al with a small amount of Fe. New phases formed by MnO acting on the surface of ZTA particles and the interfaces were MnO2·Al2O3, Mn2SiO4 and MnFe2O4. However, in the interfaces layer near the matrix, MnO was reduced by C to form Mn and Mn3C and dissolved in HCCI matrix. The hardness and modulus of the interfacial layer were 20.25 GPa and 294.7 GPa, respectively. The wear mass losses of Cr20 sample is about 4.7 times higher than that of 40 vol% ZTA particles reinforced iron matrix composites.

Preparation and mechanism of active Mo–Mn metallization on ZTA particles surface and interfacial bonding of reinforced iron matrix composite

ZrO2 toughened Al2O3 particles (ZTAp) have poor wettability with iron, and therefore some defects are easily formed at the interface between ZTAp and iron matrix, which may lead to material failure. This paper illustrates that the ZTAp were modified on the surface by the active Mo–Mn metallization, and thus, they were used as the reinforcing phases to prepare the iron-matrix composite (ZTAp/Fe composite). It is concluded that the sponge-like skeleton structure was formed on the surface of ZTAp after the metallization. The interface of ZTAp/Fe composite, which has been proved to have bearing and transitional capacity by scratch test, was formed by chemical bonding with elemental diffusion, besides mechanical bonding. The metallization mechanism of elemental diffusion can be explained by the migration of glass phase, and the elements diffusion between the interface and iron matrix is to form solid solution.

Simulation of stress distribution and evolution in SiC particle reinforced iron matrix composites

An Eshelby particle-compounded model was employed to investigate the stress distribution in the SiCp/Fe composites during straining in order to predict the stress-strain curves of the composites. Effect of the SiC volume content and aspect ratios on yield strength of the SiCp/Fe composites was studied by the simulation. The modeling results indicate that the stress in the iron matrix is much smaller than that in SiC particles as straining the composites, which means the strengthening mechanisms of the SiCp/Fe composites is determined by the load transfer mechanisms. The aspect ratios of the particles play a significant role in yield strength of the SiCp/Fe composites especially as the particle volume content is large. The stress in SiC particles has a stronger dependence on the aspect ratios of the particles only if the reinforcement volume content is small.