Experimental Studies on Mechanical Properties of Carbon Nanotube Reinforced Aluminum 7075 Composite Material

In the present work multiwalled carbon nanotubes were added as reinforcement to aluminum 7075 matrix at 0.5%, 0.75% and 1.25% by weight proportion through stir casting technique. The mechanical properties of the produced composite were studied. The composite has considerably good tensile and wear resistance properties and hence finds its best suited application in aircraft frame and wings structures. Microstructure analysis through SEM showed a uniform distribution of the reinforcement material in the matrix. XRD graphs were taken at selected points during microscopic studies to determine the chemical composition of the matrix alloy, the reinforcement and the composite. The experimental results showed that 1.25% reinforcement in the composite material exhibited a tensile strength of 560 N/mm2 and a compression strength of 649.6 N/mm2 as the highest among the compositions. Thus, the reinforcement addition at 1.25% improved the tensile and compression strength of the composite material.

The Effect of Tin Content on the Strength of a Carbon Fiber/Al-Sn-Matrix Composite Wire

The effect of tin content in an Al-Sn alloy in the range from 0 to 100 at.% on its mechanical properties was studied. An increase in the tin content leads to a monotonic decrease in the microhardness and conditional yield stress of the Al-Sn alloy from 305 to 63 MPa and from 32 to 5 MPa, respectively. In addition, Young’s modulus and the shear modulus of the Al-Sn alloy decreases from 65 to 52 GPa and from 24 to 20 GPa, respectively. The effect of tin content in the Al-Sn matrix alloy in the range from 0 to 50 at.% on the strength of a carbon fiber/aluminum-tin-matrix (CF/Al-Sn) composite wire subject to three-point bending was also investigated. Increasing tin content up to 50 at.% leads to a linear increase in the composite wire strength from 1450 to 2365 MPa, which is due to an increase in the effective fiber strength from 65 to 89 at.%. The addition of tin up to 50 at.% to the matrix alloy leads to the formation of weak boundaries between the matrix and the fiber. An increase in the composite wire strength is accompanied by an increase in the average length of the fibers pulled out at the fracture surface. A qualitative model of the relationship between the above parameters is proposed.

WEAR CHARACTERIZATION OF LM29 ALLOY WITH40 MICRON SIZED B4C REINFORCED METAL COMPOSITES

This paper deals with the fabrication and evaluation of wear properties by introducing40 micron size B4C particulates into LM29 alloy matrix. LM29 alloy based metal matrix composites were prepared by stir casting method. 3, 6 and 9 wt. % of 40 micron sized B4C particulates were added to the base matrix. For each composite, the reinforcement particles were pre-heated to a temperature of 600 degree Celsius and then dispersed in steps of two into the vortex of molten LM29 alloy to improve wettability. The Micostructural study was done by using Scanning Electron Microscope (SEM), which revealed the uniform distribution of B4C particles in matrix alloy, EDS analysis confirmed the presence of B4C particles in the LM29 alloy matrix.A pin-on-disc wear testing machine was used to evaluate the wear loss of prepared specimens, in which a hardened EN32 steel disc was used as the counter face. The results revealed that the wear loss was increased with increase in normal load and sliding speed for all the specimens. The results also indicated that the wear loss of the LM29-B4C composites were lesser than that of the LM29 matrix. The worn surfaces and wear debris were characterized by SEM microanalysis.

Production of high thermal conducting aluminum-graphite composite materials by the press-squeeze method utilizing porous graphite preforms and aluminum alloys

Consideration is given to the technological process of producing high thermal conducting aluminum-graphite composite materials by press-squeeze method utilizing porous graphite preforms and aluminum alloys. It is shown that the rate of press-squeeze process, aluminum alloy composition provide dense, defect-free and non-porous thermal interface between graphite and matrix alloy, it is noted the absence of crystal inclusions of third phases, such as SiC, Al4C3. An example of evaluation of thermal conductivity of the sample of composite material is given with consideration of graphite particles orientation and matrix-filler thermal interface heat conductivity.

Investigation of technology schemes for the production of cast composite functional materials

Obtaining and using ligatures, modifiers and deoxidizers to obtain structural alloys of a given composition and properties in metallurgy and foundry is an important production task. One of the existing developments in the field of technologies for the preparation of functional composites on a matrix basis for non-ferrous and ferrous alloys is the combination of solid filler with a melt of an active metal binder. At that, from the filler material, which is selected from the group comprising iron, nickel, titanium, silicon, boron, manganese, first a porous workpiece of a given geometric shape with a technological total pore volume is formed, then it is heated to a temperature corresponding to the liquidus temperature of the active binder, the heating being carried out in a gas inert medium, after which the heated workpiece is impregnated with the melt of this binder by forced infiltration of the melt into the pores of the workpiece under pressure, mainly by the method of liquid stamping. The task of the study was to expand the scope of use of composites, to create a single flexible universal, and at the same time, simplified technology that will provide an opportunity to obtain a wide range of diverse in composition and service characteristics of deoxidizers, modifiers and ligatures for non-ferrous and ferrous alloys. The developed technology, based on vacuum impregnation (suction) of the matrix alloy through porous filler, makes it possible to obtain new functional metal-matrix composite materials of a given composition for use as inexpensive ligatures, modifiers and deoxidizers in metallurgical processes, as well as to simplify and make their use safe. The proposed method for obtaining ligatures, modifiers and deoxidizers provides a possibility of their industrial serial production and is easy to perform, and also reduces the cost of the metallurgy product obtained with their application by increasing the effective content of active components and their more complete assimilation, which reduces the consumption of scarce and expensive materials.

On the Hardness and Elastic Modulus of Phases in SiC-Reinforced Al Composite: Role of La and Ce Addition

The use of silicon carbide particles (SiCp) as reinforcement in aluminium (Al)-based composites (Al/SiCp) can offer high hardness and high stiffness. The rare-earth elements like lanthanum (La) and cerium (Ce) and transition metals like nickel (Ni) and copper (Cu) were added into the matrix to form intermetallic phases; this is one way to improve the mechanical property of the composite at elevated temperatures. The α-Al15(Fe,Mn)3Si2, Al20(La,Ce)Ti2, and Al11(La,Ce)3, π-Al8FeMg3Si6 phases are formed. Nanoindentation was employed to measure the hardness and elastic modulus of the phases formed in the composite alloys. The rule of mixture was used to predict the modulus of the matrix alloys. The Halpin–Tsai model was applied to calculate the elastic modulus of the particle-reinforced composites. The transition metals (Ni and Cu) and rare-earth elements (La and Ce) determined a 5–15% increase of the elastic modulus of the matrix alloy. The SiC particles increased the elastic modulus of the matrix alloy by 10–15% in composite materials.

A Study On Effect of SiC And OFHC Cu-Fe29Ni17Co Reinforcement With AA7075 On Microstructure, Mechanical And Wear Rate of Hybrid Composites

The silicon carbide (SiC) reinforcement with aluminium alloy 7xxx series has been found to be limited value as per the mechanical properties and wear behaviour of previous studies. In order to improve limited mechanical properties of hybrid aluminium metal matrix composites, the SiC and OFHC Cu-Fe29Ni17Co reinforcement has been added with AA7075 alloy. Hence, the AA7075/SiC/Cu-Fe-Ni hybrid composites have been fabricated through a stir casting route under different weight percentages of SiC reinforcement. The mechanical properties such as hardness, compressive strength, tensile strength and wear rate have been investigated. The micro structure of hybrid composites found that the reinforcement particles in matrix alloy have been evenly spread. The silicon carbide and Cu-Fe-Ni alloy in aluminium solid solution has been found as well bonded interfacial reactions. The hardness, tensile strength, yield strength, compressive strength and wear rate were improved by 23.9 %, 48 %, 47 %, 15.3 % and 70 % for hybrid composite by adding 15 wt. %SiC and 15 wt. % Cu-Fe-Ni with AA7075 alloy, compared to matrix alloy.

Microstructure, Mechanical, and Corrosion Behavior of Al2O3 Reinforced Mg2Zn Matrix Magnesium Composites

Powder metallurgy (PM) method is one of the most effective methods for the production of composite materials. However, there are obstacles that limit the production of magnesium matrix composites (MgMCs), which are in the category of biodegradable materials, by this method. During the weighing and mixing stages, risky situations can arise, such as the exposure of Mg powders to oxidation. Once this risk is eliminated, new MgMCs can be produced. In this study, a paraffin coating technique was applied to Mg powders and new MgMCs with superior mechanical and corrosion properties were produced using the hot pressing technique. The content of the composites consist of an Mg2Zn matrix alloy and Al2O3 particle reinforcements. After the debinding stage at 300 °C, the sintering process was carried out at 625 °C under 50 MPa pressure for 60 min. Before and after the immersion process in Hank’s solution, the surface morphology of the composite specimens was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. With the hot pressing technique, composite specimens with a very dense and homogeneous microstructure were obtained. While Al2O3 reinforcement improved the mechanical properties, it was effective in changing the corrosion properties up to a certain extent (2 wt.% Al2O3). The highest tensile strength value of approximately 191 MPa from the specimen with 8 wt.% Al2O3. The lowest weight loss and corrosion rate were obtained from the specimen containing 2 wt.% Al2O3 at approximately 9% and 2.5 mm/year, respectively. While the Mg(OH)2 structure in the microstructure formed a temporary film layer, the apatite structures containing Ca, P, and O exhibited a permanent behavior on the surface, and significantly improved the corrosion resistance.

Microstructure and Mechanical Properties of Carbides Reinforced Nickel Matrix Alloy Prepared by Selective Laser Melting

Selective laser melting was used to prepare the ceramic particles reinforced nickel alloy owing to its high designability, high working flexibility and high efficiency. In this paper, a carbides particles reinforced Haynes 230 alloy was prepared using SLM technology to further strengthen the alloy. Microstructures of the carbide particles reinforced Haynes 230 alloy were investigated using electron microscopy (SEM), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM). Meanwhile, the tensile tests were carried out to determine the strengths of the composite. The results show that the microstructure of the composite consisted of uniformly distributed M23C6 and M6C type carbides and the strengths of the alloy were higher than the matrix alloy Haynes 230. The increased strengths of the carbide reinforced Haynes 230 alloy (room temperature yield strength 113 MPa increased, ~ 33.2%) can be attributed to the synergy strengthening including refined grain strengthening, Orowan strengthening and dislocation strengthening.