scholarly journals MICROSTRUCTURE AND MECHANICAL CHARACTERIZATIONS OF LM6-AL/AL2O3 METAL MATRIX COMPOSITES PRODUCED BY STIR CASTING TECHNIQUE

2021 ◽  
Vol 83 (5) ◽  
pp. 27-34
Author(s):  
Essam R. !. Mahmoud ◽  
A. Shaharoun ◽  
S. Z. Khan ◽  
F. O. Elmahroogy ◽  
H. Almohamadi

LM6-aluminum alloy based-metal matrix composites (MMC) reinforced with Al2O3 ceramic particles were fabricated through stir casting. Al2O3 particles with different weight content (5, 10, and 15%) were dispersed into the LM6 Al-Si alloy. The macro and microstructures, mechanical properties, fracture surface, hardness, and impact toughness of the resulted MMCs together with the plain LM6 alloy were evaluated. The results showed that the added 5 wt.% Al2O3 was distributed homogenously with good wettability. The addition of Al2O3 refined the constituents of the LM6 alloy; Al-Si dendrites and the α-Al grains. At 10 wt.% Al2O3, some localized clusters appeared with some granular cracks. Increasing the Al2O3 addition to 15 wt.% resulted in particle agglomerations with multiple cracks and porosity. Both the tensile strength and the 0.2 % proof strength of the produced MMCs were improved up to 10 wt.% Al2O3 and then reduced. The fracture surface of 5 wt.% MMC was brittle-ductile mixed-mode fracture dominated by brittle fracture. The other percentages were almost brittle fracture. The hardness of the produced MMCs was remarkably improved. The hardness value reaches to about 86 HV at 10 wt. % Al2O3 addition. The impact toughness of the resulted composite materials was decreased notably at higher addition of Al2O3.

Author(s):  
Pardeep Saini ◽  
Pradeep K. Singh

Abstract Aluminium metal matrix composites (AMCs) have become quite popular for light weight, low cost, and good workability. The present work reports the impact of silicon carbide (SiC) reinforcement on the physical, microstructural, and mechanical characteristics of Al-4032/SiC composites with 4, 6, 8% of SiC (particle size 54μm) fabricated through bottom pouring stir casting. Density and porosity measurements of all three AMCs have been performed using the rule of mixture. The microstructure of the AMC samples has been analyzed using an optical microscope (OM), x-ray diffraction analysis (XRD), and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The mechanical properties, in terms of the ultimate tensile strength (UTS), elongation, micro-hardness, and impact toughness of the AMCs have also been obtained according to American society for testing and materials (ASTM) standards. A maximum 1.52% increase in theoretical density, while a maximum 2.92% decrease in experimental density has been recorded for 8% reinforcement. The UTS, microhardness, and impact toughness of the AMC have been found to improve significantly owing to the addition of ceramic particles. The uniform distribution of SiC particles all over base Al-4032 matrix material has been noticed by SEM and OM for AMCs up to 6% reinforcement.


2013 ◽  
Vol 592-593 ◽  
pp. 614-617 ◽  
Author(s):  
Konstantinos Anthymidis ◽  
Kostas David ◽  
Pavlos Agrianidis ◽  
Afroditi Trakali

It is well known that the addition of ceramic phases in an alloy e.g. aluminum, in form of fibers or particles influences its mechanical properties. This leads to a new generation of materials, which are called metal matrix composites (MMCs). They have found a lot of application during the last twenty-five years due to their low density, high strength and toughness, good fatigue and wear resistance. Aluminum matrix composites reinforced by ceramic particles are well known for their good thermophysical and mechanical properties. As a result, during the last years, there has been a considerable interest in using aluminum metal matrix composites in the automobile industry. Automobile industry use aluminum alloy matrix composites reinforced with SiC or Al2O3 particles for the production of pistons, brake rotors, calipers and liners. However, no reference could be cited in the international literature concerning aluminum reinforced with TiB particles and Fe and Cr, although these composites are very promising for improving the mechanical properties of this metal without significantly alter its corrosion behavior. Several processing techniques have been developed for the production of reinforced aluminum alloys. This paper is concerned with the study of TiB, Fe and Cr reinforced aluminum produced by the stir-casting method.


Author(s):  
Naseem Ahamad ◽  
Aas Mohammad ◽  
Kishor Kumar Sadasivuni ◽  
Pallav Gupta

The aim of the present study is to investigate the effect of alumina (Al2O3)–carbon (C) reinforcement on the properties of aluminium matrix. Aluminium matrix reinforced with Al2O3–carbon (2.5, 5, 7.5 and 10 wt.%) in equal proportion was prepared by stir casting. Phase, microstructure, EDS, density, hardness, impact strength and tensile strength of prepared samples have been investigated. X-ray diffraction reports the intermediate phase formation between the matrix and reinforcement phase due to interfacial bonding between them. Scanning electron microscopy shows that Al matrix has uniform distribution of reinforcement particles, i.e. Al2O3 and carbon. Density decreases due to variation of reinforcement because ceramic reinforcement has low density. Hardness decreases due to variation of carbon since it has soft nature. Impact strength was found to increase with addition of reinforcement. Hybrid composite of Al and 5% Al2O3 + 5% carbon reinforcement has maximum engineering and true ultimate tensile strength. It is expected that the present hybrid metal matrix composites will be useful for fabricating stock screws.


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