A. Fathy

Effect of iron addition on microstructure, mechanical and magnetic properties of Al-matrix composite produced by powder metallurgy route

Abstract The effect of iron addition on the microstructure, mechanical and magnetic properties of Al-matrix composite was studied. Mechanical mixing was used for the preparation of 0, 5%, 10% and 15% Fe–Al composites (mass fraction). Mixtures of Al–Fe were compacted and sintered in a vacuum furnace at 600 °C for 1 h. X-ray diffraction (XRD) of the samples containing 5% and 10% Fe indicates the presence of Al and Fe peaks, while sample containing 15% Fe reveals Al and Al 13 Fe 4 peaks. The results show that both densification and thermal conductivity of the composites decrease by increasing the iron content. The presence of iron in the composite improves the compressive strength and the hardness. The strengthening mechanism is associated with the grain refinement of the matrix and uniform distribution of the Fe particles, as well as the formation of Al 13 Fe 4 intermetallic. The measured magnetization values are equal to 0.3816×10 −3 A·m 2 /g for 5% Fe sample and increases up to 0.6597×10 −3 A·m 2 /g for 10% Fe sample, then decreases to 0.0702×10 −3 A·m 2 /g for 15% Fe sample. This can be explained by the formation of the diamagnetic Al 13 Fe 4 intermetallic compound in the higher Fe content sample detected by XRD analysis.

Microstructure, mechanical and wear properties of Cu–ZrO2 nanocomposites

ABSTRACT Cu–ZrO2 nanocomposites were produced by the thermochemical process followed by powder metallurgy technique. Microstructure development during fabrication process was investigated by X-ray diffraction, field emission scanning electron microscope and transmission electron microscope. The results show an improved distribution of zirconium dioxide (ZrO2) nanoparticles (45 nm) in the copper matrix, which resulted in the improvement of mechanical properties of Cu–ZrO2 composites. The nanocomposite with 9 wt-% ZrO2 possesses the highest hardness (136.5 HV) and the superior compressive strength (413.5 MPa), resulting in an overall increase by 52 and 25%, respectively. The wear rate of the nanocomposites increased with increasing applied loads or sliding velocity.

Fabrication of Copper-Alumina Nanocomposites by Mechanochemical Routes

Nanostructure composites of Copper-Alumina were successfully produced by new mechanochemical method using two different routes. First, route A was carried out by addition of coarse copper to aqueous solution of aluminum nitrate, and second, route B was also carried out by addition of coarse copper to aqueous solution of aluminum nitrate and ammonium hydroxide. In both routes, the mixtures were heated in air and milled mechanically to get the oxides powders of CuO and Al2O3. The CuO was reduced in preferential hydrogen atmosphere into fine copper. The composite powders have been cold pressed into briquettes and sintered in hydrogen atmosphere. The structure and characteristics of powders as well as sintered composites produced from both routes were examined by XRD, SEM, EDS, TEM and metallographic techniques. The results showed that, in both routes, nano-sized particles of alumina were formed and dispersed within the copper matrix. The structure revealed the formation of CuAlO2 spinel structure at copper alumina interface. Nanocomposites produced by route-B showed finer alumina particles of 30 nm compared to 50 nm produced by route-A resulting in improved properties in terms of relative density, macro and microhardness values.

Production and properties of Cu-ZrO2 nanocomposites

In the present study, Cu–3, 6, and 9 wt.% of ZrO2 nanocomposites were prepared by an in situ reactive synthesis of copper nitrate Cu(NO3)2 and zirconium oxychloride ZrOCl2. The structure and characteristics were examined by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The results showed that the nanosized ZrO2 particles with about 45 nm was successfully formed and dispersed within the copper matrix. The effect of ZrO2 nanoparticles content on relative density, Vickers hardness, specific electrical resistivity, and coefficient of thermal expansion was evaluated. The pin-on-disc test was also performed to determine dry sliding wear behavior of specimens under different wear conditions. Hardness and specific electrical resistivity increased and density of Cu-ZrO2 nanocomposites decreased with increasing amount of ZrO2 in Cu matrix. The coefficient of thermal expansion significantly increased with increasing temperature but decreased with increasing ZrO2. The wear rate and friction coefficient of the developed surface composite was found decreasing with respect to increase in the dispersion of ZrO2. Amongst the copper surface composite, specimen with 9 wt.% of ZrO2 has shown the least wear rate with low coefficient of friction.

Evaluation of mechanical properties and microstructure of Al/Al–12%Si multilayer via warm accumulative roll bonding process

In this study, accumulative roll bonding (ARB) process was used to produce Al/Al–12%Si multilayered composites at 300℃. Microstructure and mechanical properties of the composites were studied durin...

The effects of nano-silica/nano-alumina on fatigue behavior of glass fiber-reinforced epoxy composites

This paper presents an experimental and statistical study of the fatigue behavior of unidirectional glass fiber-reinforced epoxy composite rods manufactured using pultrusion technique and modified with nanoparticles of alumina (Al2O3) and silica (SiO2) at four different weight fractions (0.5, 1.0, 2.0 and 3.0 wt.%). Tensile test was performed to investigate the influence of nanoparticles. Addition of alumina nanoparticles up to 3 wt.% increases the tensile strength by 54.76% over the pure glass fiber-reinforced epoxy specimen. For silica nanoparticles, there is an increase in the tensile strength of 31.29% for the content of 0.5 wt.% over the pure glass fiber-reinforced epoxy specimen. As the silica nanoparticles’ content increases over 0.5 wt.%, there is a decrease in the tensile strength. Rotating bending fatigue tests have been conducted at five different stress levels. Fatigue life of glass fiber-reinforced epoxy composite rods modified with alumina nanoparticles increases as the content of the nanoparticles increases. The effect of adding silica nanoparticles on the fatigue life of glass fiber-reinforced epoxy composite rods is relatively insignificant with a small improvement in the content of 0.5 wt.% silica above the pure glass fiber-reinforced epoxy specimens. Two-parameter Weibull distribution function was used to statistically analyze the fatigue life data.

Effect of Some Manfacturing Parameters on Machining of Extruded Al-Al2O3 Composites

A wide range of particulate metal matrix composites (PMMCs) of alumina and aluminum powders was formed using powder metallurgy techniques followed by extrusions at various extrusion ratios. The machining characteristics of the extruded PMMC were investigated. Results showed significant effects of weight fractions of reinforcement and extrusion ratios on tool wear and surface integrity of machined surface. The wear rate of cutting tool decreased rapidly with increasing the cutting parameters: cutting speed, feed, and depth of cut, however cutting speed is shown to be more effective. Sudden breakage of tool inserts occurred when the experiment started at high cutting speed. Wear rate has also decreased by decreasing volume fraction of reinforcement particles. Coating carbide tools have significantly improved the tool life. Coated tools showed 5% decrease in flank wear size compared to uncoated tools. This was valid within tested range of weight fractions and extrusion ratios. The surface finish of machined surfaces deteriorated when coated carbide tools were used. However, surface finish did not change significantly when volume fractions or extrusion ratios were altered.

Evaluation of mechanical properties of 1050-Al reinforced with SiC particles via accumulative roll bonding process

Accumulative roll bonding was successfully used as a severe plastic deformation method to produce Al–SiC composite sheets. The effect of the addition of SiC particles on the microstructural evolution and mechanical properties of the composites during accumulative roll bonding was studied. The Al–1, 2 and 4 vol.% SiC composite sheets were produced by accumulative roll bonding at room temperature. Monolithic Al sheets were also produced by the accumulative roll bonding process to compare with the composite samples. Field emission scanning electron microscopy revealed that the particles had a random and uniform distribution in the matrix by the last accumulative roll bonding cycles, and strong mechanical bonding takes place at the interface of the particle matrix. This microstructural evolution led to improvement in the hardness, strength and elongation during the accumulative roll bonding process. It is also shown that by increasing the volume fraction of particles up to 4 vol.% SiC, the yield and tensile strengths of the composite sheets increased more than 1.2 and 1.3 times the accumulative roll-bonded aluminum sheets, respectively. Field emission scanning electron microscopy observation of fractured surface showed that the failure broken of composite was shear ductile rupture.