Homogeneous Distribution Of SiC Particles Research Articles

Effect of a Novel Al-SiC Grain Refiner on the Microstructure and Properties of AZ91E Magnesium Alloy

Spark Plasma Sintering (SPS) process was used to fabricate a novel Al-SiC master alloy for AZ91E magnesium alloys. The master alloy enabled homogeneous distribution of SiC particles in the alloy matrix. With an addition of 0.1 wt.% Al-SiC master alloy, the mean grain size decreased by 15 %. It is proposed that binary Mg-C carbides possibly provided heterogeneous nucleation sites for grain refinement. However, further additions of Al-SiC caused grain coarsening, where formation of the MgC carbides was inhibited by precipitation of undesirable AlCMn3 intermetallic particles. The grain refining and coarsening mechanisms were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (XEDS) and differential scanning calorimetry (DSC).

Effect of Mixing Method on Microstructure of SiCp/Al Composites

The fine and homogenous distribution of the SiC particles in Al metal matrix is basic prerequisite for improving the properties of the SiCp/Al composites. In this paper, the effects of high energy ball milling and ordinary ball milling on the spatial distribution of reinforcement of the SiCp/Al composites have been investigated. The result showed that high energy ball milling is the most effective method to get homogeneous distribution of SiC particles in Al matrix. There were many clusters of SiC particles in the composites fabricated by ordinary ball milling.

Effect of Hot Extrusion on Microstructure and Mechanical Properties of P/M Al/SiC<sub>p</sub> Composite

Distribution of SiC particles in powder metallurgy (P/M) Al/SiCp composite during hot extrusion were investigated in this paper. It has been shown that a homogenous distribution of SiC particles in as-extruded rods has been achieved. There was an order and directional distribution of SiC in the longitudinal direction, which was related to the stress state associated with hot extrusion. With a small extrusion ratio (11), many obvious interfaces among the powders remained existent since the extrusion stress was not large enough to achieve a metallurgical bond. The interfacial bonding strength of the composite can be enhanced with a higher extrusion ratio, and metallurgical interfaces were achieved with the extrusion ratio of 17. Ambient tensile tests demonstrate that the mechanical properties change along with the extrusion ratio’s increasing.

Interfacial microstructure of SiCp/Al composite produced by the pressureless infiltration technique

A SiCp/Al composite was fabricated by the pressureless infiltration of an Al–Mg–Si alloy into the pre-oxidized SiC preform at 1000 °C for one hour. The composite fully infiltrated and a homogenous distribution of SiC particles was confirmed. MgAl2O4 was found as the interfacial reaction product, its formation deriving from the reactions: 2Mg+SiO2=2MgO+Si and 2MgO+4Al+3SiO2=2MgAl2O4+3Si. The factors influencing the spontaneous infiltration process were also discussed.

Effect of equal channel angular pressing and torsion on SiC-particle distribution of SiCp–Al composites

Equal channel angular pressing and torsion (ECAPT) was applied to fabricate SiCp–Al composites from the mixture of 35% SiC (volume fraction) particles and 65% Al powder. Based on microstructure observation and the quadrat method, the distributions of SiC particles in different positions of the samples and in different forming stages were studied. And the particle distribution was contrasted with that in the samples fabricated by multi-pass equal channel angular pressing (ECAP). The results show that the shear strain influences the distribution of SiC particles significantly. The distribution homogeneity of SiC particles increases greatly from the compaction stage to the angular pressing stage during ECAPT. The improvement of the particle distribution homogeneity through single pass of ECAPT process is close to that through two passes of ECAP. The relative homogeneous distribution of SiC particles is obtained through ECAPT.

Effect of SiC‐Reinforcement and Equal‐Channel Angular Pressing on Microstructure and Mechanical Properties of AA2017

AbstractThis article deals with powder metallurgical production and modification of properties of a composite material based on an age‐hardenable Al–Cu alloy. The main objective is to improve the mechanical properties by particle reinforcement and equal‐channel angular pressing (ECAP). Our approach makes use of four hardening mechanisms: precipitation hardening, particle reinforcement, strain‐hardening, and grain boundary hardening associated with an ultrafine‐grained microstructure produced by ECAP. The main processing steps are high‐energy ball milling, hot‐isostatic pressing, extrusion, heat treatment, and a single ECAP pass. Microstructures are analyzed by optical microscopy, scanning electron microscopy, and scanning transmission electron microscopy. The mechanical properties are characterized by hardness measurements and quasi‐static tensile testing. Our experimental results show that the proposed processing route results in a nearly homogeneous distribution of SiC particles in the matrix. The combination of particle reinforcement and ECAP leads to an improvement of ultimate tensile strength by almost 300 MPa compared to the unreinforced alloy. A subsequent heat treatment leads to a further increase in hardness and strength that can be related to changes in the defect structure. Our study provides detailed information on how processing steps, microstructures, and mechanical behavior are interrelated in this technologically relevant class of materials.

Metal matrix composite production by means of laser dispersing of SiC and WC powder in Al alloy

The properties and processing parameters of the metal matrix composite (MMC) surface layers, obtained under conditions of the superposition of intense laser radiation with the kinetic effect due to gas-dynamically controlled particle injection, are investigated for the case of laser dispersing of the SiC and WC powders in the soft Al 6061 alloy. With substrate preheating above 600 K the nearly homogeneous distribution of SiC particles up to depths of about 1 mm, characterized by their content of about 35% by volume, is revealed by the scanning electron microscopes (SEM) inspection. In the microstructure the presence of the Al 4C 3 plates separated by the eutectic regions of Si–Al is observed and confirmed by the X-ray diffraction (XRD) and energy-dispersive spectrometer (XEDS) measurements. The surface layers (25 cm 2) consisting of parallel processing traces show the wear rate of about 3 × 10 −4 mm 3/N m which is markedly lower than that of the reference substrate. For WC under similar processing conditions the particle enriched layer of thickness of about 100 μm is covered by the alloy material. The experimental data confirm that laser dispersing combines the advantages of the soft matrix with these of the wear and corrosion resistant material, and results in the improvement of the properties of composite material.

Mechanical alloying process and mechanical properties of Cu–SiCp composite

A composite of copper powder and SiC particle reinforcement was prepared by mechanical ball milling and subsequent sintering. Proper choice of processing parameters ensured a homogenous distribution of SiC particles in the copper matrix. Microstructure, powder morphology and mechanical properties of the composite were investigated as a function of milling time. With increasing milling time, the dentritic copper powder became flattened, which subsequently became spherical shaped. Mechanical properties of the composites change with the distribution of SiC.

Microstructures and wear property of friction stir welded AZ91 Mg/SiC particle reinforced composite

The microstructures and wear property of friction stir welded AZ91 Mg alloy/SiC particle reinforced composite (AZ91/SiC/10p) were investigated. The initial microstructures of the AZ91/SiC/10p were composed of irregularly distributed β-phases (Al 12Mg 17) and agglomerated SiC particles, while the friction stir weld zone was characterized by the homogeneous distribution of SiC particles, the recrystallized grain structure and the dissolution of β-phase. Thank to the microstructural modification, an improvement in the hardness and wear property of the weld zone were observed as compared to those of the base metal. The hardness near the weld zone was a higher and more homogeneously distributed and the wear resistance within the weld zone, as evaluated by the specific wear loss, was superior, as compared with the base metal.

Preparation of Al2O3/SiC nanocomposites with in-situ formed SiC

Powder mixtures containing Al 2 O 3 , SiO 2 and carbon black were calcined at 1625°C to form nanoscaled SiC within Al 2 O 3 by means of the carbothermal reduction of SiO 2 . The prepared powders contained 5 and 10 vol. % SiC. These powders were densified by hot pressing, and composite ceramics with densities up to 99 % obtained. Microstructural analyses of the hot-pressed composites showed a homogeneous distribution of SiC particles with a particle size mainly under 100 nm. The fracture mode was intragranular. The fracture toughness determined by the ICL method using the Niihara approach for Palmqvist cracks was in the range of 5 MPa·m 0,5 . The fracture strength determined in a four-point bending test was around 540 MPa for the hot-pressed samples and around 630 MPa for the hot-pressed and post-annealed samples.

Processing of squeeze cast Al6061–30vol% SiC composites and their characterization

6061 aluminum matrix composites containing 30vol% SiC with mean mass particle size of 16 and 22 μm as the reinforcing phase were synthesized by squeeze casting route. The process consisted of fabricating of SiC preform followed by squeeze casting of 6061 aluminum alloy. The SiC preform was made by blending SiC particles with silica as a coal and sintering. The microstructural features, aging behavior, mechanical properties and wear characteristics of the composites were investigated. The results indicated that a homogenous distribution of SiC particles in the aluminum matrix, which is almost free of pores, can be obtained by squeeze casting method. Higher strength and lower wear rates were observed in the composite materials than the unreinforced aluminum alloy part. However, a marked decrease in ductility of the composites arising from adding of SiC particles was obtained. The aging behavior of the aluminum alloy was found to be influenced by the reinforced materials, i.e. the time to obtain the peak hardness in T6 treatment was lower for the composites than the unreinforced material. The fracture surfaces of the unreinforced and composite samples exhibited dimple surfaces. The wear resistance of the aluminum alloy was improved by reinforcing with SiC particles and it is comparable with unalloyed pearlitic cast iron. This article presents the effect of SiC particles on the aging behavior, mechanical properties and wear resistance of 6061 aluminum alloy made by squeeze casting method.

Microstructure Formations in Copper-Silicon Carbide Composites During Mechanical Alloying in a Planetary Activator

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Influence of microstructure and texture on mechanical properties of aluminium alloy 2124 + 5%SiC particulate composites

A study of texture, microstructure, mechanical properties, and crack propagation mechanisms was carried out on aluminium alloy 2124 reinforced with 5 vol.-%SiC particles (3 μm). Three fabrication techniques have been used to produce the composites. composite I wasfabricated by blending followed by hot isostatic pressing. composite II was fabricated by mechanical alloying followed by hot isostatic pressing. composite III wasfabricated by agglomeration of aluminium powder by mechanical alloying followed by blending with SiC and hot isostatic pressing. All three composites were hot rolled to nominally 12.5 mm thick plate. Similar textures were observed for all composites. A model of the observed texture is {001} (211), {111} (211), and {211} (111) for rolling, side, and transverse planes respectively. Composite I showed a homogeneous distribution of SiC particles. Transmission electron micrographs of composite I showed good interface bonding, stacking faults present in SiC particles, and segregation of aluminium, oxygen, copper, and magnesium to the interface. composites II and III showed an inhomogeneous distribution of SiC particles. The elastic modulus was slightly higher in the (211) direction than in the (111) direction. The fracture toughness of composite I was higher in the (211) crack direction whereas that for composite II and composite III was higher in the (111) crack direction. Secondary crack propagation modes follow the crystallographic orientations of {100} and {111} planes.

Al2O3─SiC Composites from Aluminosilicate Precursors

Al2O3 and SiC composite materials have been produced from mixtures of aluminosilicates (both natural minerals and synthetic) and carbon as precursor materials. These composites are produced by heating a mixture of kaolinite (or synthetic aluminosilicates) and carbon in stoichiometric proportion above 1550°C, so that only Al2O3 and SiC remain as the major phases. A similar process has also been used for synthesizing other composite powders having mixtures of Al2O3, SiC, TiC, and ZrO2 in different proportions (all compounds together or selective mixtures of some of them), as desired. The microstructure of hot‐pressed dense compacts, produced from these powders, revealed that the SiC phase is distributed very homogeneously, even occasionally within Al2O3 grains on a nanosize scale. The homogeneous distribution of SiC particles within the system produced high fracture toughness of the hot‐pressed material (KIC∼ 7.0 MPa · m1/2) and having Vicker's hardness values greater than 2000 kgf/mm2.

Low-temperature ductility of iron

6061 aluminum matrix composites containing 30vol% SiC with mean mass particle size of 16 and 22 μm as the reinforcing phase were synthesized by squeeze casting route. The process consisted of fabricating of SiC preform followed by squeeze casting of 6061 aluminum alloy. The SiC preform was made by blending SiC particles with silica as a coal and sintering. The microstructural features, aging behavior, mechanical properties and wear characteristics of the composites were investigated. The results indicated that a homogenous distribution of SiC particles in the aluminum matrix, which is almost free of pores, can be obtained by squeeze casting method. Higher strength and lower wear rates were observed in the composite materials than the unreinforced aluminum alloy part. However, a marked decrease in ductility of the composites arising from adding of SiC particles was obtained. The aging behavior of the aluminum alloy was found to be influenced by the reinforced materials, i.e. the time to obtain the peak hardness in T6 treatment was lower for the composites than the unreinforced material. The fracture surfaces of the unreinforced and composite samples exhibited dimple surfaces. The wear resistance of the aluminum alloy was improved by reinforcing with SiC particles and it is comparable with unalloyed pearlitic cast iron. This article presents the effect of SiC particles on the aging behavior, mechanical properties and wear resistance of 6061 aluminum alloy made by squeeze casting method.