Addition Of SiCp Research Articles

Microstructure evolution and mechanical response of hetero-induced SiCp addition in Al-6061 under high strain rate compressive loading

Al/SiC composites having a high-volume fraction of SiC are eye-catching materials in the automobile and aerospace industries. However, their behavior under stringent environments i.e., under high strain rate compression is much different than quasi-static compression. For such conditions, the morphology, interfacial bonding, and the fraction of the SiC play a decisive role in achieving the high performance of the Al/SiC composites. Here, in this study, we reported that a transitional effect of de-bonding and intergranular crack in SiC has occurred in Al–SiC composites having SiC particle size >0.7 μm. Below the 0.7 μm, the diffusion of the Al dislocations is characterized on the boundary of SiC along with the strong interfacial bonding. To prove it, we have fabricated an Al6061/30 vol% SiC composite through powder metallurgy route and subsequently subjected to compression in the range of strain rate 0.001–2100 s−1. In support of our observations, the microstructure was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction, electron backscattered diffraction, and transmission electron microscopy analysis. The result also revealed a positive strain rate sensitivity up to a strain rate of 1800 s−1, while for 2100 s−1, the flow stress decreased, which is the cause of adiabatic temperature rise, dynamic recrystallization in Al, and massive cracks and deboning in coarse SiC particles. We also characterized that the SiC having particle size 1–4 μm showed stacking fault and dislocation induced in the SiC due to strong interfacial bonding. A quantitate analysis of dislocation was also established by using the Williamson-Hall technique which further confirmed the dislocation activity and dynamic recrystallization in 2100 s−1, characterized by EBSD and TEM. Thus, this study enables our understating that using the fine SiC particles is promising for achieving the high performance of the Al/SiC composites for use in stringent environments.

Interfacial microstructure of dual-scale SiCp/A356 composites investigated by in situ TEM tensile testing

Silicon carbide particle (SiCp) reinforced Al matrix (SiCp/Al) composites have broad application prospects in high-end equipment manufacturing fields such as aerospace and automotive nowadays. The volume fraction and size of SiCp reinforcement play a decisive role in the physical and mechanical properties of the composites. Herein, we have prepared the dual-scale SiCp/Al composites through the powder metallurgy method. The interfacial microstructure and crystal orientation relationship at the interface was observed and analyzed. And then we have investigated the fracture behavior of the SiCp/Al interface by employing the in situ TEM tensile experiment. The results of the in situ TEM tensile testing show that when there exists a MgAl2O4 interface layer with thickness of 100 nm in the prepared SiC/Al composite, the microcracks are formd preferentially at the MgAl2O4/Al. And the interface bonding strength of the SiC/MgAl2O4 is higher than that of MgAl2O4/Al. Moreover, the microcracks are formed firstly at the sharp corners of micron SiCp and the interface. With the increaing load, the microcracks propagate along the micron SiCp and the interface. With the further increase of the load, connections and mergers will occur between the formed microcracks, which will eventually lead to the breakage of the specimen. Besides, the addition of the dual-scale SiCp can improve the yield strength of the A356 obviously.

The investigation of strength-ductility mechanism of bimodal size SiCp/Mg–Zn matrix composite

Mg–Zn–Al matrix composites reinforced with bimodal-size SiCp (average size of ∼8 μm and ∼60 nm) are fabricated by semi solid stirring casting process and extrusion process. The influence of bimodal size SiCp on microstructure and texture evolution, mechanical properties as well as work hardening behavior of Mg–Zn–Al matrix composites are investigated. The results reveal that the area fraction of unrecrystallization (unDRX) region decreases from 12.8 % of matrix alloy to 5.2 % of 9 wt% m-SiC+1 wt% n-SiC/Mg–6Zn–3Al-0.5Ca(M9N1) composite, and the average grain size (AGS) is reduced sharply with addition of SiCp, which decreases from 7.3 μm of matrix alloy to 0.9 μm of M9N1 composite. The addition of micron SiCp (m-SiCp) promotes the generation of nano precipitates, and the precipitate size is reduced further after the addition of nano SiCp (n-SiCp). The intensity of basal texture decreases firstly and then increases with the addition of m- and n-SiCp because of the pinning effect from n-SiCp and nano precipitates for grain boundary. The bimodal-size SiCp particles have been observed to significantly enhance the strength of the composite. The M9N1 composite demonstrates exceptional performance, and its yield strength and ultimate tensile strength is 322 MPa and 360 MPa, respectively. The exceptional strength of the composite can be attributed to various strengthening mechanisms, including grain refinement, precipitate strengthening, dislocation strengthening, and the load transfer effect.

Simultaneously improved modulus, thermal expansion coefficient and wear resistance of a Mg–6Zn–1Gd–0.3Ca matrix composite by adding high volume fraction SiC particles

In this paper, three sizes (5, 20 and 50 μm) SiC particles (SiCp) were selected, and the SiCp/Mg–6Zn–1Gd-0.3Ca (SiCp/ZG61X) composites with ∼50 vol.% were successfully prepared by squeeze casting. The effect of particle size on the properties of the composites was studied, while the wear resistance and the wear mechanism of composites were investigated. The results showed that compared with the matrix alloy, the addition of SiCp can significantly improve the properties of the composites, in which the strength increased from 175.2 to 326.5 MPa and the modulus increased from 45.0 to 159.6 GPa. At the same time, the coefficient of thermal expansion and friction were significantly reduced. In addition, the smaller the particle size, the higher the strength and modulus of the composite. However, for the coefficient of friction and thermal expansion, the larger particle size was conducive to the reduction of the two coefficients. The analysis of friction and wear behavior showed that the wear mechanism of the matrix alloy was mainly abrasive wear and adhesive wear, while the wear mechanism of the composites was abrasive wear and layered wear.

Effect of SiCp on the microstructure and tensile properties of the Mg–3Y magnesium alloy

Magnesium matrix composite is another competitive light metal matrix composite following aluminum matrix composite, with excellent application prospects in the aerospace and automotive fields. In this paper, the Mg - 3Y – xSiCp (x = 0, 1, 3, 5 wt%) composites are fabricated by stir casting with ultrasonic vibration followed by extrusion. The microstructure of the alloys is investigated by means of scanning electron microscopy (SEM) imaging and electron backscatter diffraction (EBSD) techniques. The results reveal that the composites have a finer grain size due to the particle promoted nucleation (PSN) mechanism. When the SiCp content is 3 wt%, the grain size is the smallest (0.76 μm), and the refinement rate is about 16.7%. Moreover, the addition of SiCp can inhibit the transformation from low-angle grain boundaries (LABGs) to high-angle grain boundaries (HABGs), thus hindering the dynamic recrystallization (DRX) of the alloy, which decreases from 55.7% to 15.4%. The reduction in the proportion of recrystallized grains in the composite leads to increasing the maximum intensity of the texture. In addition, the tensile properties and the strengthening mechanism of the alloys are investigated. The results show that the composites have higher ultimate tensile strength (UTS) and yield strength (YS) due to the combination of grain refinement and dislocation strengthening. When the SiCp content is 5 wt%, the UTS (291 MPa) and YS (283 MPa) increase by ∼12.7% and ∼17.1%, respectively, over the matrix alloy. However, the addition of SiCp causes more oxides and holes in the alloys, which leads to a fracture strain (δ) decrease in the composites.

The corrosion resistance and discharge performance of as-extruded AZ91 alloy synergistically improved by the addition of submicron SiCp

In order to reveal the influence of submicron SiCp on the corrosion and discharge behaviors of extruded AZ91 alloy, the extruded AZ91 alloy and 0.5 μm SiCp (0.5 vol.%)/AZ91 composite were subjected to immersion, electrochemical, and Mg-air battery tests. The results show that the introduction of submicron SiCp not only reduces the weightless corrosion rate of the extruded AZ91 alloy from 3.09 mm/y to 2.18 mm/y, but also increases its discharge voltage and stability at current densities ranging from 2.5 mA cm−2 to 40 mA cm−2. The improvement of corrosion resistance and discharge activity are attributed to the refined grains and precipitates, as well as the weakened basal texture owing to the addition of the minor submicron SiCp. Extruded AZ91 alloy has a coarse and unevenly distributed Mg17Al12 phase and strong basal texture. The coarse phase and more grains with basal texture as cathode lead to the local corrosion of magnesium in the corrosion process and the local dissolution of magnesium in the discharge process. After adding 0.5 vol.% submicron SiCp, the Mg17Al12 phase is fined and evenly distributed, and the basal texture is weakened, which not only weakens the galvanic corrosion but also promotes the uniform corrosion of magnesium. As a result, the corrosion resistance is improved. In addition, the discharge activity benefits from refined grains and the easily dissolving discharge product resulting from uniform dissolution of magnesium. This work provides new ideas for achieving the synergistic improvement of corrosion resistance and discharge performance of magnesium alloy.

Recrystallization Behavior of a Mg-5Zn Alloy Influenced by Minor SiCp during Hot Compression

The influence of minor SiCp on the dynamic recrystallization (DRX) and dynamic precipitation behaviors of the Mg-5Zn matrix were investigated through the hot compression test. The results showed that the addition of SiCp improved the DRXed ratio of Mg-5Zn matrix, but the recrystallized grains in 1 vol.% 5 μm SiCp/Mg-5Zn material were mainly formed by the "bulging" nucleation of the grain boundary at a low compressive strain (~0.05, ~0.1 and ~0.35), and PDZ (particle deformation zone) around SiCp had little effect on the recrystallization nucleation. However, the fine recrystallized grains appeared around the particles when the compressive strain reached ~0.7, which was attributed to the promotion effect of PDZ on recrystallization nucleation. This shows that PDZ around particles can promote DRX nucleation under large strain. Meanwhile, compared to the Mg-5Zn alloy, the volume fraction and size of the secondary phase in the SiCp/Mg-5Zn material increased due to the influence of SiCp on the recrystallization behavior of Mg-5Zn matrix.

Oxidation performance of particle-reinforced Ti750 matrix composites

This study used SiCp, SiCw, B4C, and GPLs as reinforcements for Ti750 matrix alloy and composites synthesized by spark plasma sintering. The oxidation performances of the composites were then evaluated at 800 °C. 5 vol.% SiCp reinforced Ti750 composite recorded the least oxidation weight gain of 3.80 mg.cm−2, about 41.8% of the base alloy. The average oxidation rates K + of the five materials at 800 °C were less than 1 g.m−2.h−1, indicating all materials were within the anti-oxidation grade with excellent anti-oxidation performance. The oxidation products of the samples contained TiO2, Al2O3, and SiO2. 5 vol.% SiCp reinforced Ti750 composite had significantly flatter and denser oxide film, which was well bonded with the matrix thus having a better protective effect than the matrix material. With the addition of SiCp, the thickness of the oxide film decreased, and the resistance of the material significantly improved its high-temperature oxidation performance.

Influence of micron and nano SiCp on microstructure evolution and mechanical properties of laser metal deposition AlSi10Mg alloy

In this work, laser metal deposition (LMD) technique was applied to fabricate SiCp/AlSi10Mg composites. Innovatively, the effect of SiCp of different scale (micron, submicron and nano scale) on the microstructure and mechanical properties was studied. With the decrease of SiCp size, the reaction between SiC and aluminum matrix was more intense, and the volume fraction of Si precipitates and grain boundary Al-Si eutectic phase increased. Few micro-SiCp and agglomerated nano-SiCp were all unevenly distributed in the aluminum matrix, which caused the bimodal distribution of grain size in varying degrees. The mechanisms of defect formation, phases evolution and mechanical property enhancement were also discussed. Due to the agglomeration of nano-SiCp and its decomposition under laser irradiation, the seriously uneven microstructure of nano-SiCp/AlSi10Mg limited the mechanical properties. Moreover, the addition of SiCp increased the Marangoni flow instability of molten pool, leading to the high porosity and reducing the tensile strength of composites, which was more prominent in the samples containing micron and nano SiCp. Submicron-SiCp/AlSi10Mg presented uniform equiaxed crystals and the best comprehensive mechanical properties (microhardness 118.37HV, wear rate 1.60 ×10−3 mm3N−1m−1 and UTS 269.08 MPa). Based on the experimental results, adding multi-scale reinforcements will be more conducive to the performance optimization of composites. This study provides theoretical guidance for the engineering application of SiCp/Al composites.

The corrosion properties of AZ91 alloy improved by the addition of trace submicron SiCp

In this work, the 0.5 μm SiC particles (0.5, 1, 2 vol.%)/AZ91 composites were prepared by ultrasonic-assisted semi-solid stirring casting. The effect of submicron SiC particles (SiCp) on the microstructure and corrosion behavior of AZ91 alloy was studied. It indicated that the introduction of submicron SiCp induced the β-Mg17Al12 phase to preferentially form by wrapping the SiCp, which breaks the semi-continuous network structure of the β-Mg17Al12 phase in the alloy. Interestingly, the formation of lamellar (α-Mg+β-Mg17Al12) structures and fine β-Mg17Al12 phase was promoted by adding trace submicron SiCp (0.5 vol.%) into the alloy. During corrosion process, the lamellar (α+β) structure can act as corrosion barrier and fine β-Mg17Al12 phase can be shed. In addition, the potential difference between α-Mg and β-Mg17Al12 decreased. These can explain this phenomenon that the weight loss corrosion rate of the alloy was reduced from 8.85 mm/y to 1.23 mm/y by adding trace submicron SiCp (0.5 vol.%). However, the precipitation of granular β-Mg17Al12 phase increased with the increase of SiCp content, which inhibits the formation of lamellar (α+β) structure. Concurrently, the content of Al in the matrix reduced gradually, which makes the matrix potential decrease gradually. Consequently, the corrosion resistance of composites decreased gradually with the increase of SiCp content.

Synergistic Effect of Sic Particles and Whiskers on the Microstructures and Mechanical Properties of Ti(C,N)-Based Cermets.

The microstructure and mechanical properties of Ti(C,N)-based cermets with the addition of the SiC particles (SiCp) and SiC whiskers (SiCw), were systematically studied in this work. Firstly, the effect of SiCp on the cermets was investigated independently to determine the considerable total amounts of additives, and the results showed that 2.0 wt.% SiCp would lead to optimal properties of the cermet. Then, the influence of SiCp and SiCw additions with the variable ratio on the cermets was studied. The results indicated that when 1.5 wt.% SiCp and 0.5 wt.% SiCw were added; the cermets appeared with the best comprehensive properties, and the transverse rupture strength, hardness, and the fracture toughness of the cermets reached 2520.8 MPa, 88.0 HRA, and 16.56 MPa·m1/2, respectively. This was due to the synergistic strengthening and toughening effect afforded by the reasonable SiCp and SiCw addition, from which the smallest grain size, as well as the most uniform, and completed core-rim structure of the cermets, were achieved.

Enhanced Mechanical Properties of SiCw/ SiCp-Reinforced Mg Composites Fabricated by Spark Plasma Sintering

This study aims to fabricate SiC whisker (w)/ particle (p)-reinforced magnesium (Mg) composites with enhanced mechanical properties using spark plasma sintering (SPS) methods. It has been confirmed that dispersing state of SiCw can be improved by addition of SiCp. However, due to presence of voids and cracks between the oxide layers, surrounding SiCw/p, and Mg matrix in the composites, SiCw with SiCp cannot contribute to enhance the bending strength of Mg matrix. This issue can be tackled by adding low melting point metals such as Sn into the composites to fill the defects in the composites.

Enhancement of mechanical properties of SiCw/ SiCp-reinforced magnesium composites fabricated by spark plasma sintering

This study aims to fabricate SiC whisker (w)/particle (p)-reinforced magnesium (Mg) composites with enhanced mechanical properties using spark plasma sintering (SPS) methods. It has been demonstrated that dispersing state of SiCw can be improved by addition of SiCp, while voids and cracks between the oxide layers near SiCw/p, and Mg matrix can degrade bending strength of the composites. This issue can be tackled by adding low melting point metals such as Sn to fill the defects in the composites.

Hot deformation behavior and dynamic recrystallization mechanism of an Mg-5wt.%Zn alloy with trace SiCp addition

The influence of trace (3 vol%) silicon carbide particle (SiCp) addition on the hot deformation behavior of the Mg-5wt.%Zn (Mg–5Zn) alloy was studied through the hot compression test. The activation energy of the Mg–5Zn alloy is decreased by the addition of trace SiCp, which is due to the high dislocations density in particle deformation zone (PDZ) around SiCp stimulates the pipe diffusion. Moreover, the activation energy of the composite also decreases with the increase of the size of PDZ (dPDZ). Additionally, the optimum deformation condition of 3 vol% 20 μm SiCp/Mg–5Zn composite is 693 K and 0.1–0.01s−1 according to the processing map. The instability region of the processing map at 543 K and 1 s−1 disappears with the increase of strain, which is associated with the inhibitory effect of trace SiCp on {101¯2} extension twins and promoting effect on the dynamic recrystallization (DRX) within {101¯1} contraction twins and {101¯1}-{101¯2} double twins by introducing flow localization. Moreover, the DRX behavior of the 3 vol% 20 μm SiCp/Mg–5Zn composite was analyzed by EBSD technology. The DRX mechanisms of the composite at 543 K and 1 s−1 are continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN) and twining dynamic recrystallization (TDRX). With the increase of temperature, the DRX mechanisms are discontinuous dynamic recrystallization (DDRX) and PSN.

Effect of SiCp reinforcement on mechanical properties of Al 6061 by Powder Metallurgy

Silicon carbide reinforced aluminium have been developed since past 3 decades for many structural and automotive applications especially for manufacturing gears due to their excellent characteristics such as light weight, high strength, good wear resistance and other mechanical properties. Gears are transmission components that requires high wear resistance as well as self-lubrication properties while performing the needed operations. The present research elucidates the addition of particle reinforcement with Al6061 with particle size 50 µm and different weight percentages of Silicon carbide (SiCp) such as 3, 6 and 9 for gear blank application. The addition of SiCp with Al6061 enhance its properties and provides prolonged use of gear for many applications. In this study, the gear blank has been produced via traditional powder metallurgy method by adding Zinc stearate as binding agent. The compacted green part was further processed with sintering process with 500°C in muffle furnace. The sintered gear blank was examined for mechanical properties such as hardness and surface roughness according to ASTM standards. The influence of SiCp with Al6061 were evaluated by incrementing the SiCp. It was seen that there was an increase in the hardness showing the dispersion of hard particles SiCp throughout the structure. Further, the surface roughness varied depending on the process and heat treatment of compacted composites. This study gives better understanding about the effect SiCp reinforcement on mechanical properties of Al6061 metal matrix.

Tensile and compression behaviour, microstructural characterization on Mg-3Zn-3Sn-0.7Mn alloy reinforced with SiCp prepared through powder metallurgy method

In this research paper, Mg-3Zn-3Sn-0.7Mn/SiC composite is developed by reinforcing various weight fractions of SiCp in Mg-3Zn-3Sn-0.7Mn alloy through powder metallurgy route. The weight fraction of SiCpusage is varied from 3% to 15% in Mg-3Zn-3Sn-0.7Mn alloy (i.e., in Mg-3Zn-3Sn-0.7Mn/xSiC; the sample values are varies for x is 3, 6, 9, 12 and 15%). The effect of SiCp addition got tested against its tensile strength, compression behavior, hardness, microstructure, alloying nature and porosity. This study shows better grain refinement with improved properties while reinforcing Mg-3Zn-3Sn-0.7Mn alloy with 6 wt% SiC composites. It was observed that the grain refinement occurred while adding up to 6 wt% of SiC particles in the composite and thereafter increase in SiC caused little grain refinement effect. Hardness is getting increased with the increase of SiC weight fraction and reached maximum to 133 HV at 12SiC/ Mg-3Zn-3Sn-0.7Mn. Higher UTS of 293 MPa obtained from the sample prepared with 12%SiC for 0.0533 s−1 strain rate. The highest UCS of 341 MPa is obtained from the sample made with 15%SiC inclusion for 0.0.0533 s−1strain rate. From the SEM fracture analysis, the Mg-3Zn-3Sn-0.7Mn alloy and Mg-3Zn-3Sn-0.7Mn/SiC composite exhibit the almost same type of fracture called quasi-cleavage regardless of the % addition of SiC reinforcement. It was observed that the increase of SiC weight fraction increases the UCS because of its increased load-bearing capacity and reduction in cleavage facets.

Hot tensile behavior and deformation mechanism of Mg–5Al–2Ca alloy influenced by SiC particles

Multiple physical and metallurgical influences exerted by SiC particles (SiCp) still make it difficult to understand that how the addition of SiCp affects the hot tensile deformation behavior of Mg matrix alloy. A deformation mechanism analysis method developed in this study is promising to find a reasonable answer on this problem, via the comparison of SiCp/Mg–5Al–2Ca composite (SiCp/AC52) and Mg–5Al–2Ca alloy (AC52). The effects of SiCp on the constitutive description, deformation mechanism, strain hardening and softening behavior are specially investigated based on the microstructure evolutions, true stress-strain behaviors and fracture characteristics of the uniaxial tensile tests under the deformation temperatures of 290–350 °C and strain rates of 8.3 × 10−4-1.67 × 10−2 s−1. The grains exhibit different growth levels during the hot tensile deformation, and it becomes more evident with the decrease in the strain rate and the increase in the temperature. The addition of SiCp restrains grain growth and leads to a refined and homogeneous grain microstructure. The flow stress at low strain rate is increased with the addition of SiCp, while, which is decreased by SiCp when the strain rate over 8.3 × 10−3 s−1. The addition of SiCp leads to the tress exponent value n and the activation energy value Q increasing from 1.56 and 90.33 kJ/mol to 2.94 and 110.77 kJ/mol, respectively. The dominating deformation mechanism is altered corresponding to the strain rate. The addition of SiCp causes the local stress/strain redistribution, restrains the grain boundary sliding and facilitates the dislocation climb creep in the hot tensile deformation. Moreover, such addition stimulates the generation and coalescence of previously-induced small voids or dimples, while inhibits its extension and enlargement. As a result, the fracture morphologies exhibit an intergranular ductile fracture combined with micro-dimple growth and coalescence.

The Effect of Micro-SiCp Content on the Tensile and Fatigue Behavior of AZ61 Magnesium Alloy Matrix Composites

AZ61 magnesium alloy metal matrix composites (MMCs) with different weight percentages (0, 1 and 2) of micro-silicon carbide particles (SiCp) were fabricated using stir casting method. Effects of SiCp on the microstructural distributions, mechanical and fatigue properties, and fracture surfaces have been investigated. The microstructural observations of as-cast MMCs unveil the existence of primary α-Mg phase and the presence of large amount of β-Mg17Al12 secondary phase at grain boundary. The specimens are subjected to homogenization heat treatment at 410 °C for 24 h; the β-Mg17Al12 phases are significantly dissolved in the matrix grain boundaries which enhance the ductility and decrease the hardness compared with the as-cast materials. The addition of SiCp reinforcement led to improved yield strength (YS) and ultimate tensile strength (UTS) of AZ61/SiCp composite compared to the unreinforced alloy. The maximum values of YS and UTS have been attained at AZ61/1wt%SiCp composites. The enhancement of YS and UTS was due to the presence of a uniformly distributed reinforced SiCp, which depends on grain refinement of the matrix and strong interfacial bonding between the matrix and reinforcement. In the case of fatigue test results, the addition of SiCp reduced the fatigue life and strength of AZ61 alloy composite. However, addition of 1wt%SiCp showed good mechanical and fatigue properties compared to pure AZ61 magnesium alloy and AZ61/2wt%SiCp composite. Furthermore, the effects of addition of SiCp on the mechanical and fatigue properties of the composite were confirmed by using the scanning electron microscope observation of fracture surfaces.

Improved workability of an Mg-5 wt.%Zn alloy by the addition of trace SiCp

The influence of trace SiCp (1 vol%, 5 μm) on the workability and processing map of an Mg-5 wt.%Zn (Mg–5Zn) alloy over a temperature range of 543–693 K and strain rate range of 0.001–1 s−1 was investigated. The results indicated that the workability domains in the processing map of the Mg-5Zn alloy were effectively expanded by the addition of trace SiCp. The addition of trace SiCp refined the initial grain size (from ∼60 μm to ∼20 μm) of the Mg-5Zn alloy, so the flow stress of the alloy was reduced at 543–593 K. The opposite situation was observed at 643 and 693 K because of the resistance of trace SiCp to dislocations. The critical strain, constitutive equation, and processing map were investigated based on the flow stress. The addition of trace SiCp led to an earlier occurrence of dynamic recrystallization (DRX) by reducing the critical strain of the Mg-5Zn alloy. The power constitutive equation was demonstrated to be the most suitable constitutive relation for the Mg-5Zn alloy and SiCp/Mg-5Zn composite. Moreover, the activation energy Q of the Mg-5Zn alloy decreased from 170.3–126.4 kJ/mol by the addition of trace SiCp.

Preparation, mechanical properties, and toughening mechanisms of SiCw/SiCp‐reinforced zirconia‐toughened alumina ceramics

ABSTRACTZirconia‐toughened alumina (ZTA) ceramics with high mechanical properties were sintered by hot‐pressing method using SiC particles (SiCp) and SiC whiskers (SiCw) as the reinforcing agents simultaneously. The influences of sintering temperature, SiCp, and SiCw contents on the microstructure and mechanical properties of ZTA ceramics were investigated. It was found that both SiCp and SiCw could contribute to grain refinement significantly and promote the mechanical properties of the ceramics. However, the excess addition of SiCp or SiCw led to the formation of pores with large sizes and degraded the mechanical properties instead. When 13 wt% SiCp was introduced, the maximum flexural strength of 1180.0 MPa and fracture toughness of 15.9 MPa·m1/2 were obtained, whereas the maximum flexural strength of 1314.0 MPa and fracture toughness of 14.7 MPa·m1/2 were achieved at 20 wt% SiCw. Interestingly, the simultaneous addition of SiCp and SiCw could further improve the mechanical properties, and the highest flexural strength of 1334.0 MPa and fracture toughness of 16.0 MPa·m1/2 were achieved at a SiCw/SiCp ratio of 16/4. The reinforcement mechanisms in the ceramics mainly included the phase transformation toughening of ZrO2, the crack deflection and bridging of SiCp and SiCw, and the pull‐out of SiCw.