Microstructure and Mechanical Properties of Al-Mg-Si Hybrid Composites Reinforced with SiC/TiO2

The current work aims to investigate the influence of adding different weight percents of TiO2 and SiC 1.5:0,3:0, 4.5:0, 0:1.5, 0:3, 0:4.5, 1.5:1.5, 3:3, 4.5:4.5 particulate reinforcement on mechanical and microstructure characters of base alloy Al-Mg-Si. The base alloy and composites as hybrid were set via method of stir casting. The mechanical characters of base alloy and composites as hybrid were detected by using hardness and tensile tests. The electron microscope as scanning (SEM) and spectroscopy of dispersive energy (EDS) were utilized for inspection of the topography of fracture surfaces. The results were showing that the strength of tensile as ultimate, strength of yield, and hardness,elevated with elevating the weight reinforcement percentage to 4.5% of TiO2/ SiC. In contrast, the rate of elongation is decreased. The optical microscope inspection represents that the particles distribution in the matrix is uniform without any voids. The X-Ray diffraction manifested the presence of different phases and inter metallic compounds Mg5Si6, Mg2Si, Al2O3, Mg6Si3.3., Al3Mg2 and Al3Ti.


Introduction
The composites of the aluminum metal matrix have been extensively utilized in numerous sectors, including consumer devices, sports and the automobile industryDue to its best properties for corrosionresistant, low density, optimal thermal and electric conductivity, and improving precipitation strength the alloys are more active [1].Aluminum metal composites have either carbides or oxides in the aluminum matrix which have unique features, rather than the Al-alloys matrix (SAM), (SiC,ALN,B4C,TiC,Si3N4,TiO2,TiO2).Increased drift resistance, abrasion resistance , excellent strength and stiffness-to -weight ratios, and size stability are required [2]. Composites of aluminum matrix provide superior mechanical properties and wear power in contrast of steel, regardless of slipping intensity and load. This is primarily because the harsh particles like Al2O3, WC and SiC, etc, when dispersed into the matrix, limit and improve the temperature of the base alloys [3].
Most of the composite materials reinforced with particles by liquid metallurgy method (or so-called vortex method) have the advantage over the traditional techniques as simple, inexpensive, good binding to the matrix, more comfortable to control the composition of the mixture, flexibility, and application for larger production quantities.
Numerous studies and researches have been published in this field. Ashok et al.[4] proved the best wear parameters of Aluminum6061-T6 reinforced by adding 15wt%Al2O3 and 15 wt% SiC particulates having a particle size of 37 μm. The results represent that the incorporation of Al2O3 and SiC prefers to an increasing the erosion resistance of the hybrid compounds. Kenneth et al. [5] studied Al-Mg-Si's rice husk ash and silicone carbohydrate wear and corrosion component .Mixed in weight ratios 0:1, 1:0 1:3, 1:1, and 3:1 rices, ash and silicone carbide were also added.The findings demonstrate that the erosion tolerance of mixed composites is higher than the alloy Al-Mg-Si matrix that is just filled with silicon carbide.In addition, a corrosion resistance improved by 3.5 percent naphthon solution, enriched with rice peel and silicone carbide. Kataiah et al. [6] studied the effect of TiO2 with particles size 30-50 µm additions by different weight percentage 0% to 20% on mechanical characteristics of Al-Mg-Si base alloy.The production of compounds using vortex methods. Results showed that the ultimate strength and hardness increased, but the flexibility decreased as the weight percentage of strengthening increased. Alaneme et al. [7] investigatedAl-Mg -Si alloy enriched with alumina and bamboo leaf ash (BLA) for corrosion and wear. The reinforcement powder consists of 0:10, 2:8,3:7, and 4:6 theleaf ash of the bamboo and alumina weight percentage one after the other.The corrosion and wear test to assess the composite resistance in 3,5 NaCl solution.The wear of the single-and hybrid fiber, which has been researched using 25 N, was used at 5 Hz level for 1,000 seconds.The results represent that the corrosion resistance of the composites decreased to 3.5 % NaCl when added BLA, but wear rates for hybrid composites with 4% BLA were shown to be higher than composites. PSYCHOLOGY AND EDUCATION (2021)  In this research, we used two types of particles (SiC and TiO2) with particle size (<75µm) as a reinforcement phase embedded in Al-Mg-Si as a matrix phase, the table(1)Show alloy chemical composition. Figure (1)& (2) represent the SEM and EDS examination of powders.The alloy Al-Mg-Si was made in an aluminum sink in the electric oven at temperature 700oC and then poured in 250oC into the prepared base alloy in the pre-heated steel mould. The composites have been prepared by stir casting method where the base alloy melted over a temperature of the fluid in an electrical furnace at 750 °C.For homogenization chemical composition the fusion was held at this temperature for approximately 15 min, then added flux(1%wt.). In addition to a mechanical stirrer, gradually added reinforcement materials (silicone carbide and titanium oxide) have been added to the moulded alloy, which have been preheated with 1.5:0.3:0,4.5:0,0:1.5,0:3,0:4.5,1.5:1,5,3:3,4.5:4.5 wt percent by aluminum foil for 1 hour to remove humidity and to enhance stability by melting Al-Mg-Si alloy af, pre-heated to 550°F.The wettability between base metal and reinforcement was increased by adding magnesia (1wt percent).Then grinding is carried out in the pre-heated mold and the composite material is filled with SiC and TiO2 pieces.After the preparation of all samples of the base alloy and composites, it has been done a machining process(turning) for castings according to the standard dimensions required for each test.

3-1 Microstructure examination
The alloy cast and composite hybrid samples from Al-Mg-Si (15x10), is cut in measurements. By grinding and polishing, the samples were then grated with 1 %HF.A metallurgical microscope with an Optical digital camera was used to study the microstructure for the preparations. Electron Microscopy Scanning and Spectrometer Energy Distribution (EDS)detector have been used type of (VEGA 3 LM)to research the topographical structure and the micro-chemical structure of reinforcements and tensile specimens. The resulting phases of basic alloy and composites have been tested for X-ray diffraction.

3-2 Tensile test
After being prepared as (ASTM E8) standard (figure 3), the tensile test was carried out using the machine Instron(DWD-200E) for the samples..

3-3 Hardness test
The Vickers research tester has been used for the calculation of strength of the base material and composites.The applied load was(200g) for dwell time(15sec). And five readings of hardness value were taken in each sample to more accuracy.

4.Results and discussion
4.1 SiC and TiO2 additives influence on al-Mg-Si alloy microstructure alloy The best uniform dispersion of ceramic reinforcement particles is the most important factor to achieve a homogeneous property of discontinuously reinforced composite material. Figure (4 to 7) Figure demonstrates the almost nodulous microstructure and distribution of it in the matrix in a business with particle coalescence throughout the grain boundaries and within the grain partly uniform. The contact between ceramic reinforcing particles and aluminum melt is anticipated to produce an interaction layer that enhances the wettability of the base alloy and ceramic particles. The interface between the metal matrix and strengthening in the base alloy reaction is extremely important because the high interfacial connection allows the load from the matrix to be transferred and distributed to the support. Figures (8 to17) highlighted findings for X-ray diffraction indicating the precipitation -Al phase and different intermetallic compound such as Mg5Si6, Mg2Si, Al3Mg2, Mg6Si3.3, Al3Ti and Al2O3. Figure 18 refers to the link between strengthening and yield strength, final strength and elongation in weight percentages. The ultimate strength and yield increased with the proportion weight of support, while the elongation rate fell.This nature because of attributed to the tight connection between particles and matrix of existence of hardened ceramic objects [9]. The X-ray showed the presence of different intermetallic compounds, such as (Mg5Si6, Mg2Si3.3, Al3Mg2, Mg2Si., Al3Ti, and Al2O3). The differences in the matrix and ceramic particles in the thermal expansion coefficient led to the decrease in the density of the matrix[10].In going through the dislocations of the scattered particulates in a matrix, these particles are used as an obstruction to twisted base alloy because the high resistance inter-facial bonding process enabling process transmission between matrix and the active coherence between the reinforcing part and base alloy (TiO2 and SiC particles).Also, the elongation decreases due to increasing brittleness of ceramic particles. Fig(19 www.psychologyandeducation.net scanning electron microscope. A bimodal array of dimples is primarily the fracturing surface of substances supported by TiO3 and SiC particulate matter. In the other hand, tenside composites fragmented in a fragile manner with no visible neck structure and a few good dicks are related to the ductile fracturing of the matrix.It could be because of the growth of the void nucleation, and coalescence occurred quickly. In addition, local tension concentration positions at the arming and matrix interface are responsible of the expression of a local crack activation and enhanced embrittlement effect. Result   Fig(30)manifeststhe relation between basic alloy, composite and hybrid composite hardness values. The increased weight percentage of reinforcing particles as grains of composite material are refined, has shown that composite hardness increases.The improvement in composite stiffness is attributed to its strong toughness, hence rising power by the Hall Petch equation, which represents The link between durability and the size of grain which obstructs the dislocation movement also demonstrates a higher hardness than the single composite in the composite hybrid.Resistance to locally deformed plastic is that due to the fact that particles are an obstacle to dislocations and that Mg6Si3.3 is also known to be the most powerful intermetallic compound precipitate such as Mg2Si, Al3Mg2, Al3Ti and Al2O3.The further pottery particles applied to the mixture, the greater the inter-particulate difference between TiO2 and SiC hard particles, the greater the dislocated row. One of the great benefits of this dispersal enhancing effect is its conservation even for long periods and high temperatures. Fig shows also that the composite hardness increases resistance to dislocation [11].The improvement in composite toughness is attributed to the strong hardening particles, to increase in resistance to localized plastic deformation because of dislocation impairments in particulate matter and because of the needle shaped β "Mg2Si process which is also called the most effective hardening precipitate also, Mg2Si3.3, Al3Mg2, Mg2Si, Al3Ti and Al2O3 precipitated intermetallic solution [12,13]. The reduction in the inter-particulate gap between hard TiO2 and SiC particles contributing to an rise in dislocation piles owing to introduction of more ceramic particles to the compounds. The great benefit of this dispersion strengthening impact is its durability even at high temperatures for long periods of time. Fig(28)demonstrated that silicon carbide composite reinforcement has a stronger hardness than tianium oxide composite because SiC is tougher than TiO2 and has a lower composition [13,14].

Conclusions
1-Improve the base metal microstructure by incorporating titanium oxide and carbides in silicone particles where the arrangement varies approximately from dendrites to the configuration of the parallel axes. 2-With the weight of TiO2 and SiC additions decreased, the stiffness improved. 3-Additional voltage and power of TiO2 and SiC are rising by weight. 4-The elongation decreases for one and mixed compositeswith TiO2 and SiC increasing in weight percentage.