Processing and mechanical properties of SiC reinforced cast magnesium matrix composites by stir casting process (original) (raw)
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International Journal of Surface Science and Engineering, 2012
Particle reinforced magnesium metal matrix composites (MMCs) and related manufacturing methods are among important research topics because of their low density, high specific stiffness, strength and wear resistance. SiC p /Mg composites are commonly used materials for fabrication of lightweight functional components. Magnesium powders with mean size of 69 μm were used as raw material while reinforcement material was selected as SiC p with the average particle size of 84 μm. Different amounts of SiC p (3, 6, and 9 wt. %) were added to the magnesium matrix and the composite materials were sintered in a vacuum furnace at 590°C. Structural characterisation of the produced composites was performed using several techniques such as scanning electron microscopy (SEM) and X-ray diffraction. The green density of the composite materials increased with SiC p addition. The hardness of the composites was found to be higher than the pure Mg. Reinforcement with 9 wt. % SiC p showed significant increase in the compressive strength of magnesium matrix composites.
A new semi-solid casting technique for fabricating SiC-reinforced Mg alloys matrix composites
Composites Part B-engineering, 2016
The capability of the newly developed rheocasting (RC) technique in combination with the RheoMetal process for producing SiC particulate-reinforced AM50 and AZ91D matrix composites (Mg-based MMCs) was investigated. The quality of the MMCs was studied by analyzing the fraction of casting pores, number density of SiC clusters and the uniformity of SiC particles. Solid fraction, particle size and oxidation of SiC particles had strong impacts on the overall quality of the MMCs. The MMCs produced by 40% solid fraction and oxidized micron-sized SiC particles exhibited an excellent casting quality. A low-quality MMC was obtained when non-oxidized sub-micron sized SiC particles were employed. The results showed the formation of various types intermetallic particles and carbides such as MgO, Mg 2 Si, Al 2 MgC 2 , Mg 2 C 3 , Al 4 C 3 as the interfacial reaction products of SiC/Mg alloy's melts. Mg hydride (a-MgH 2) was also identified in inter-dendritic regions of the MMCs for the first time.
Fabrication and Characterizations of Mg/SiC Composite Via Compo-Casting Technique
The present work deals with applying compo-casting technique for fabrication of magnesium matrix composite under an inert gas atmosphere. A 15 Micrometer average diameter size of -SiC particulate was used as a reinforcement material with different volume fractions. The effect of processing technique on SiC distribution within alloy matrix was investigated using light optical microscope and scanning electron microscope. Also, microstructural characterization studies conducted on the composites produced by compo-casting technique revealed a uniform distribution of SiC particulates (at the microscopic scale) and less porosity content. The mechanical properties of pure Mg and Mg-SiC composites have been evaluated. The results show a remarkable increasing in hardness value, tensile strength and 0.2% yielding strength. The increasing in overall mechanical properties revealed to SiC addition to base matrix. However, it is also evident that the strain to failure significantly decreased as the volume fraction of the particulate increased. Also, a good bonding between Mg matrix and SiC reinforcement material was observed in fracture surface SEM micrograph.
Processing, microstructure, and mechanical behavior of cast magnesium metal matrix composites
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, 1995
A. LUO Magnesium metal matrix composites (MMCs) have been receiving attention in recent years as an attractive choice for aerospace and automotive applications because of their low density and superior specific properties. This article presents a liquid mixing and casting process that can be used to produce SiC particulate-reinforced magnesium metal matrix composites via conventional foundry processes. Microstructural features, such as SiC particle distribution, grain refinement, and particle/matrix interfacial reactions of the cast magnesium matrix composites, are investigated, and the effects of solidification-process parameters and matrix alloys (pure Mg and Mg-9 pct AI-1 pct Zn alloy AZ91) on the microstructure are established. The results of this work suggest that in the solidification processing of MMCs, it is important to optimize the process parameters both to avoid excessive interfacial reactions and simultaneously achieve wetting, so that a good particle distribution and interfacial bonding are obtained. The tensile properties, strain hardening, and fracture behavior of the AZ91/SiC composites are also studied and the results are compared with those of the unreinforced AZ91 alloy. The strengthening mechanisms for AZ91/SiC composite, based on the proposed SiC particle/matrix interaction during deformation, are used to explain the increased yield strength and elastic modulus of the composite over the magnesium matrix alloy. The low ductility found in the composites is due to the early appearance of localized damages, such as particle cracking, matrix cracking, and occasionally interface debonding, in the fracture process of the composite.
Materials, 2019
In the present study, Mg nanocomposites with a high volume fraction (10 vol %) of SiC particles were fabricated by two approaches: mechanical milling and mixing, followed by the powder consolidation steps, including isostatic cold pressing, sintering, and extrusion. A uniform distribution of the high content SiC particles in a fully dense Mg matrix with ultrafine microstructure was successfully achieved in the mechanically milled composites. The effect of nano- and submicron-sized SiC particles on the microstructure and mechanical properties of the nanocomposites was evaluated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), and X-ray diffractometry (XRD) were used to characterize microstructures of the milled and mixed composites. Mechanical behavior of the Mg composites was studied under nanoindentation and compressive loading to understand the effects the microstructural modification on the strength and ductility o...
Advanced Production Process and Properties of Die Cast Magnesium Composites Based on AZ91D and SiC
Journal of Materials Engineering and Performance, 2009
The driving force behind the efforts to develop magnesium metal matrix composites (MMC) via high-pressure die casting is the requirements for advanced applications under severe operational conditions in terms of stress, temperature, and corrosion resistance. Therefore this study aims to explore the mechanical properties of die cast Mg-MMC in terms of hardness and strength, as well as its corrosion resistance. AZ91D was chosen as the most commonly used magnesium alloy. The choice as the reinforcement agent that has to be an economical and non-reactive addition was silicon carbide particles (SiC P ) with an average particle size of 10 lm. The challenge was production of high quality, homogeneous material with good mechanical properties and acceptable corrosion resistance. The results revealed the advantages of a die cast Mg-MMC as a new attractive alternative for advanced structural applications that can be used for mass production.
In the present study, rheocasting process was adopted to synthesise AZ91D composites reinforced with silicon carbide (SiC) particulates. Particle-matrix interfacial reaction, distribution of particles, hardness and mechanical properties of as cast and T4 heat-treated alloy-composites were reported. The rheocast composite materials reveal uniform distribution of SiC particulates. The composite materials show an increase in hardness and elastic modulus compared to unreinforced rheocast alloy. She ultimate tensile strength and ductility of composite materials were lower than those of the unreinforced alloy. 15 lm particles-composite shows significantly higher elastic modulus than the 150 lm SiC particles-composite.
Effect of SiC Reinforcement and Its Variation on the Mechanical Characteristics of AZ91 Composites
Materials, 2020
In this study, the processing of SiC particulate-strengthened magnesium alloy metal matrix composites via vacuum supported inert atmosphere stir casting process is presented. The effects of small variations in the SiC particulate (average size 20 µm) reinforcement in magnesium alloy AZ91 were examined. It was found that with the addition of SiC particulate reinforcement, the hardness improved considerably, while the ultimate tensile and yield strength improved slightly. The density and porosity of the magnesium alloy-based composites increased with the increase in the wt.% of SiC particulates. The tensile and compressive fracture study of the fabricated composites was also performed. The tensile fractures were shown to be mixed-mode fractures (i.e., ductile and cleavage). The fractured surface also disclosed tiny dimples, micro-crack, and cleavage fractures which increases with increasing reinforcement. For the compression fracture, the surface microstructural studies of AZ91 displa...
Journal of Mechanical Engineering Science and Technology ISSN 2580-0817, 2022
Al-SiC is a composite composed of AA6061 as a matrix and SiC as a reinforcement particle. The variation of mass added will affect the mechanical properties of the composite because Al-SiC is hardenable, which means that its mechanical properties can be improved by adding the reinforcement component. However, an excessive portion of SiC leads to a decrease in mechanical properties. The purpose of this study was to find the optimal composition of the addition of SiC into the aluminium matrix to gain maximum tensile strength and hardness. The mass fraction variation that would be used in this composite was the addition of 6%, 8%, and 10% SiC with the addition of 1% Mg as a wetting agent. The mixing process used the stir casting method. The process of adding SiC and Mg was carried out by melting the aluminium while stirring it for a certain time before it went to the furnace. The ASTM E8/E8M standard was used for observing the tensile strength of the specimens. Machining was carried out before testing. The specimens were also tested for hardness using the Rockwell hardness method. The result shows that the addition of SiC at the amount of 6%, 8%, and 10% SiC increased the ultimate tensile strength by154.10 MPa, 175.01 MPa, and 198.14 MPa, respectively. Similarly, the hardness also increased up to 30.1 HRF, 48.1 HRF, and 66 HRF, respectively. Microstructure observation also confirmed that a 10% SiC fraction results in less defect and good wettability. The addition of 10% SiC and 1% Mg resulted in maximum tensile strength and hardness and the best microstructure.