Synthesis of Copper Metal Matrix Hybrid Composites Using Stir Casting Technique and Its Mechanical,Optical and Electrical Behaviours

New kind of MMCs have been developed using the economical stir casting technique, where pure copper is taken as matrix and alumina (Al₂O₃) of grade 6, zirconia (ZrO₂), tungsten carbide (WC) and chromium (Cr) are utilized as reinforcements. The developed hybrid composites are characterized through HR-SEM, XRD to identify the phases of the materials. However, EDAX is done to reveal the atomic and weight percentage of reinforced elements present in the composites. Brinell hardness, compressive strength and tensile strength of the Al₂O₃ based developed hybrid composites show much better results compared to ZrO₂ based hybrid composites and its matrix. This is attributed to the particle strengthening and load transfer effect of harder Al₂O₃. Overall electrical property of the developed hybrid composites decreases on reinforcement, which is measured by a four-probe technique. Optical properties are investigated through FTIR, UV–VIS-NIR and fractured surfaces are analysed by SEM.     

Comparison in the Oxidation and Corrosion Behavior of Aluminum and Alumina-Reinforced Ni/Ni-Co Alloy Coatings

In this study, a comparison in the oxidation and corrosion behavior of Ni/Ni-Co aluminum and alumina-reinforced electrodeposited composites has been made. The developed coatings were characterized for the morphology, structure, microhardness, oxidation, and corrosion resistance. It was found that the incorporation of Al particles in NiCo matrix is higher (9 wt pct) compared to Ni matrix (1 wt pct). In the case of aluminum oxide particles, about 5 and 7 wt pct had been obtained in Ni and NiCo matrices respectively. The difference in the surface morphology was observed with respect to metallic (Al) and inert ceramic (Al₂O₃) particle incorporation. X-ray diffraction studies showed the presence of predominant Ni (200) reflection in the coatings. Also, peaks corresponding to Al and Al₂O₃ particles were present. The Ni/NiCo-Al coatings exhibited higher microhardness values at 1273 K (1000 °C) compared to alumina-reinforced coatings, indicating better thermal stability of the former coatings. The NiAl coating showed one and two orders of magnitude improved oxidation resistance compared to NiCoAl and Ni/NiCo-Al₂O₃ coatings, respectively. It was observed that the Ni-Al composite coating exhibited poor corrosion resistance in 3.5 pct NaCl solution compared to the other coatings studied.     

Internal friction in AlCu-Al2O3 metal-matrix composites

In metal-matrix composites (MMCs), the metal matrix is exposed to plastic deformation and damage accumulation in the region close to the reinforcements, following mechanical or thermal stress. In this connection, Al-4 wt pct Cu-based MMCs reinforced with 20 vol pct Al₂O₃ fibers were characterized by internal friction (IF) measurements. The IF measurements as a function of the vibration amplitude present a solid friction peak connected with the loosening of metal-fiber interfaces, while plastic deformation was associated with a high amplitude IF background. On this basis, IF measurements allowed us to identify the distribution of internal stresses and damage accumulation at matrix-fiber interfaces or plastic flow in the matrix in different thermomechanical conditions. Furthermore, IF measurements allowed damage accumulation consequent to mechanical fatigue to be followed.     

Preparation of Aluminum Metal Matrix Composite with Novel In situ Ceramic Composite Particulates, Developed from Waste Colliery Shale Material

A novel method is adapted to prepare an in situ ceramic composite from waste colliery shale (CS) material. Heat treatment of the shale material, in a plasma reactor and/or in a high temperature furnace at 1673 K (1400 °C) under high vacuum (10^?6 Torr), has enabled in situ conversion of SiO₂ to SiC in the vicinity of carbon and Al₂O₃ present in the shale material. The composite has the chemical constituents, SiC-Al₂O₃-C, as established by XRD/EDX analysis. Particle sizes of the composite range between 50 nm and 200 μm. The shape of the particles vary, presumably rod to spherical shape, distributed preferably in the region of grain boundaries. The CS composite so produced is added to aluminum melt to produce Al-CS composite (12 vol. pct). For comparison of properties, the aluminum metal matrix composite (AMCs) is made with Al₂O₃ particulates (15 vol. pct) with size <200 μm. The heat-treated Al-CS composite has shown better mechanical properties compared to the Al-Al₂O₃ composite. The ductility and toughness of the Al-CS composite are greater than that of the Al-Al₂O₃ composite. Fractographs revealed fine sheared dimples in the Al-CS composite, whereas the same of the Al-Al₂O₃ composite showed an appearance of cleavage-type facets. Abrasion and frictional behavior of both the composites have been compared. The findings lead to the conclusion that the in situ composite developed from the colliery shale waste material has a good future for its use in AMCs.     

Synergistic effects of wear and corrosion for Al2O3 particulate-reinforced 6061 aluminum matrix composites

Wear corrosion of alumina particulate-reinforced 6061 aluminum matrix composites in a 3.5 wt pct NaCl solution with a revised block-on-ring wear tester has been investigated. The studies involved the effects of applied load, rotational speed, and environments (dry air and 3.5 pct NaCl solution) on the wear rates of materials. Also various specimens with Al₂O₃ volume fractions of 0, 10, 15, and 20 pct were employed in this work. Electrochemical measurements and electron micrographic observations were conducted to clarify the micromechanisms of wear corrosion in such metal matrix composites. Experimental results indicated that the wear rate of monolithic 6061 Al in either dry wear or wear corrosion was reduced by adding alumina reinforcements. However, the effect of volume fraction on wear rate is only minor in dry wear, while it is significant in the case of wear corrosion. Wear-corrosion tests also showed that the corrosion potential shifted to the active side and the current density for an applied potential increased with the decrease of Al₂O₃ volume fraction in the materials and the increase in applied load and rotational speed. Although the incorporation of reinforcement in these aluminum matrix composites was deterimental to their corrosion resistance, the influence on wear corrosion was favorable.     

Processing copper and silver matrix composites by electroless plating and hot pressing

A simple process was developed to fabricate ceramic-reinforced copper and silver matrix composites by electroless plating and hot pressing at 873 K and 300 MPa, in air. Composites were produced containing 10 to 40 vol pct ceramic reinforcements of different sizes and shapes including silicon carbide whiskers (SiC _w ), alumina particles (Al₂O_3p ), carbon short fibers (Carbon _sf ), and Saffil short fibers (Saffil _sf ) (3.8 pct SiO₂-96.2 pct Al₂O₃) uniformly distributed within the matrix. The hardness and bending strength of the composites were much higher than those of the pure matrices. The electrical conductivity, measured by a four-point probe method, was similar to that of traditional CdO/Ag electrical contact materials. The surface morphologies and cross-sectional microstructures of the arc-eroded Al₂O_3p /Ag composites were similar to those of conventional CdO/Ag and SnO₂/Ag and exhibited a good arc-erosion resistance. These composites combine the high strength and elevated-temperature stability of the ceramic reinforcements with the good electrical and thermal conductivity of the two metallic matrices.     

Interfacial reactions in aluminosilicate short fiber-reinforced aluminum matrix composites

Aluminosilicate short fibers are one of the less expensive reinforcements used for the fabrication of metal matrix composites (MMCs). The present investigation evaluates the interfacial characteristics of Al-7Si-0.4Mg (356) alloy reinforced with 10 wt pct aluminosilicate short fibers using optical microscopy, electron microscopy, and X-ray analysis. The fibers used are standard- and zirconiagrade aluminosilicate short fibers. The interfacial analysis has shown the formation of MgAl₂O₄ and Si in both grades of fibers. In addition, ZrAl₃ formation is observed in the zirconia-grade fiber because of the interaction between the matrix and the dispersoid. The zirconia-grade fiber is more susceptible to interfacial reaction than the standard-grade fiber because of the presence of the highly reactive ZrO₂ phase and a lower amount of the Al₂O₃ phase, which provides resistance to the reaction.     

Study of 6061-Al2O3p composites produced by reciprocating extrusion

A reciprocating extrusion process was developed to consolidate 6061-Al₂O_3p composites from mixed powders. The 6061 alloy powder was first dehydrated in a vacuum chamber at 450 °C and then mixed with 12.5 μm Al₂O₃ powder in various volume fractions: 0, 5, 10, 20, and 30 pct. The mixed powders were hot pressed at 300 °C under a pressure of 300 MPa and finally extruded reciprocatingly 14 times at 460 °C. The results show that the composites were fully densified, with no sign of pores or oxide layers observable in the optical microscope. The Al₂O₃ particles were distributed uniformly in the matrix. As compared with 6061 alloys, the composites demonstrated a smaller precipitation hardening and elongation, but exhibited a higher Young’s modulus and a larger work hardening capacity. The degradation of precipitation hardening was due to the loss of Mg, which reacts with Al₂O₃ to form MgAl₂O₄. The large work-hardening capacity is attributable to the incompatibility between Al₂O₃ and the matrix, which possibly generates more dislocations to harden the matrix. The composites had much higher friction coefficients and greater wear resistances than the 6061 alloy against steel disc surface. The friction coefficient of the 6061-30 vol pct Al₂O_3p composite was double that of the 6061 alloy and the wear resistance was 100-fold. As compared with similar composites reported previously, these composites possessed much higher elongation at the same strength level. A 30 vol pct Al₂O_3p still displayed an elongation of 9.8 pct in the T6 condition. All of these improvements are attributed to the merits, including full densification of the bulk, uniform dispersion of the Al₂O₃ particles in the matrix, and strong binding between the Al₂O₃ particles and the matrix resulting from reciprocating extrusion.     

Fabrication of Dense ZrO2/CNT Composites: Influence of Bead-Milling Treatment

Highly concentrated zirconia-carbon nanotube (CNT) water suspensions were prepared using an advanced milling technique. The bead-milling operation parameters were optimized for this system and used to prepare zirconia-stabilized water-based suspensions with different CNT contents. The effects of different milling conditions were studied. The particle dispersion was evaluated by SEM observations on dried suspension. Green’s density and SEM observations of compacts were used to follow the colloidal dispersability of the composites. Materials of tetragonal zirconia and CNTs were prepared with a high concentration of CNTs (1, 5, and 10 wt pct CNT). The homogeneous dispersion and distribution of the fibers in the bulk material after slip casting of the suspension were examined. The samples were sintered using spark plasma sintering (SPS) at 1473 K (1200 °C) and finally, fully dense materials were obtained. The mechanical properties were evaluated using the Vickers indentation technique.     

Coating of 6028 Aluminum Alloy Using Aluminum Piston Alloy and Al-Si Alloy-Based Nanocomposites Produced by the Addition of Al-Ti5-B1 to the Matrix Melt

The Al-12 pctSi alloy and aluminum-based composites reinforced with TiB₂ and Al₃Ti intermetallics exhibit good wear resistance, strength-to-weight ratio, and strength-to-cost ratio when compared to equivalent other commercial Al alloys, which make them good candidates as coating materials. In this study, structural AA 6028 alloy is used as the base material. Four different coating materials were used. The first one is Al-Si alloy that has Si content near eutectic composition. The second, third, and fourth ones are Al-6 pctSi-based reinforced with TiB₂ and Al₃Ti nano-particles produced by addition of Al-Ti5-B1 master alloy with different weight percentages (1, 2, and 3 pct). The coating treatment was carried out with the aid of GTAW process. The microstructures of the base and coated materials were investigated using optical microscope and scanning electron microscope equipped with EDX analyzer. Microhardness of the base material and the coated layer were evaluated using a microhardness tester. GTAW process results in almost sound coated layer on 6028 aluminum alloy with the used four coating materials. The coating materials of Al-12 pct Si alloy resulted in very fine dendritic Al-Si eutectic structure. The interface between the coated layer and the base metal was very clean. The coated layer was almost free from porosities or other defects. The coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages (1, 2, and 3 pct), results in coated layer consisted of matrix of fine dendrite eutectic morphology structure inside α-Al grains. Many fine in situ TiAl₃ and TiB₂ intermetallics were precipitated almost at the grain boundary of α-Al grains. The amounts of these precipitates are increased by increasing the addition of Al-Ti5-B1 master alloy. The surface hardness of the 6028 aluminum alloy base metal was improved with the entire four used surface coating materials. The improvement reached to about 85 pct by the first type of coating material (Al-12 pctSi alloy), while it reached to 77, 83, and 89 pct by the coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages 1, 2, and 3 pct, respectively.     

Microstructures and Tensile Properties of Hot-Extruded Al Matrix Composites Containing Different Amounts of Al4Sr

In this investigation, the effect of hot extrusion process has been studied on the microstructure and tensile properties of aluminum matrix composite containing different amounts (10, 15, and 20 wt pct) of Al₄Sr intermetallic phase. Microstructural examinations assessed by scanning electron microscopy revealed that hot extrusion breaks large Al₄Sr particles and reduces their length tremendously. It was also found that although the addition of Al₄Sr content in the composite reduces ultimate tensile strength and elongation values, hot extrusion improves tensile results significantly. Remarkable result of this study was concerned with significant improvement in the toughness of hot-extruded Al-10 wt pct Al₄Sr composite in which elongation values raised up to 22 pct. Therefore, optimum amount of Al₄Sr intermetallic in the composite was found to be 10 wt pct. Fractographic examinations revealed that hot extrusion encourages ductile mode of fracture by introducing homogeneous distribution of fine dimples on the fracture surface of the composites.     

Tribological Behavior of A356/Al2O3 Surface Nanocomposite Prepared by Friction Stir Processing

Surface A356 aluminum alloy matrix composites containing micro and nanosized Al₂O₃ are prepared by a new approach utilizing high-velocity oxy-fuel spraying and friction stir processing (FSP). Optical and scanning electron microscopy, microhardness, and wear tests were used to characterize the surface composites. Results indicated that, the presence of Al₂O₃ in matrix can improve the mechanical properties of specimens. The microhardness of surface composites containing micro and nanosized Al₂O₃ were 89.8 ± 2.6 HV and 109.7 ± 2.5 HV, respectively, which were higher than those for the as-received (79.6 ± 1.1 HV) and the FSPed A356-T6 with no alumina powder (66.8 ± 0.9 HV). Surface composites revealed low friction coefficients and wear rates, which were significantly lower than those obtained for substrate. The wear mass losses of the as-received, the FSPed, and surface micro and nanocomposite specimens after 500-m sliding distance were 50.5, 55.6, 31, and 17.2 mg, respectively. Scanning electron microscopy tests revealed different wear mechanisms on the surface of the wear test specimens.     

Combustion synthesis of YAG:Ce phosphors via the thermite reaction of aluminum

Cerium-doped yttrium aluminum garnet(YAG:Ce) as a yellow phosphor for white light-emitting diodes(LEDs) was synthesized via a facile combustion method using Y_2 O_3, CeO_2, Al_2 O_3, Al,and NaClO_4 as raw materials. The combustion synthesis approach utilizes the strong exothermic oxidation of aluminum to realize a self-sustaining reaction. In this study, we investigated the effects of the ratios of Al_2 O_3 to AI,fluxes, and coprecipitated materials as raw materials on the luminescence properties of the synthesized YAG:Ce phosphors. When the amount of Al_2 O_3 x is varied, the combustion reaction proceeds at x ≤ 1.8,with x = 1.725 being the optimum condition for producing a high-performance product. When 5 wt%BaF2 is added, the luminescence intensity is significantly improved owing to a decrease of YAP(YAlO_3)formation with improved uniformity. However, the addition of CaF_2 and NaF does not improve the luminescence properties. To suppress the segregation of CeO_2, we used the coprecipitated material Y_2 O_3-CeO_2 as a raw material. Unlike with separate addition of Y_2 O_3 and CeO_2, Ce ions are uniformly distributed in the coprecipitated material, resulting in improved luminescence properties. The combination of BaF_2 and coprecipitated material significantly improves the internal quantum efficiency to83.0%, which is close to that of commercial phosphors.     

The apparent solubility of aluminum in cryolite melts

The apparent solubility of aluminum in cryolite melts saturated with A1₂O₃ has been determined by titration with electrolytically generated O₂. The results may be expressed by wt pct Al = − 0.2877 + 0.0268 (NaF/AlF₃ wt ratio) + 2.992 × 10⁻⁴ (temp °C) − 0.00192 (% CaF₂) −0.00174 (% Li₃AlF₆) −0.00288 (% NaCl) with a standard deviation of ±0.017. Ranges covered were ratio 0.8 to 2.3, temperatures 969° to 1054°C, CaF₂ ≤ 14 pct, Li₃AlF₆ ≤ 20 pct, and NaCl ≤ 10 pct. There was no significant effect of adding 0 to 38. pct K₃A1F₆ or 0 to 10 pct MgF₂. It was found that solubility was approximately proportional to activity of aluminum when Al-Cu alloys were used. Possible mechanisms of solution are discussed. Monovalent aluminum is ruled out on the basis of the variation of solubility with NaF/AlF₃ ratio and a_Al. The favored, but not proven, mechanism involves formation of both sodium atoms and a colloidal dispersion of aluminum.     

Effect of Al2O3 and CaO/SiO2 on the Viscosity of Calcium-Silicate–Based Slags Containing 10 Mass Pct MgO

The effect of Al₂O₃ and CaO/SiO₂ on the viscosity of the CaO-SiO₂-10 mass pct MgO-Al₂O₃ slags was studied at fully liquid temperatures of 1773 K (1500 °C) and below. At fixed CaO/SiO₂ between 0.8 and 1.3, higher Al₂O₃ content increased the slag viscosity due to the polymerization of the aluminate structures. At fixed Al₂O₃ of 15 and 20 mass pct, increasing the CaO/SiO₂ from 0.8 to 1.3 resulted in lower viscosity due to the depolymerization of the aluminate structure.     

Effect of Sulfur in Steel on Transient Evolution of Inclusions During Calcium Treatment

In the current study, the effect of S content in the molten steel on inclusions during calcium treatment was studied using an induction furnace. The calcium in steel decreased from 48 to 2 ppm, and the sulfur in steel changed a little with time. When sulfur content in steel was as low as 25 ppm during calcium treatment, inclusions shifted from CaO-Al₂O₃-CaS to Al₂O₃-CaO with about 35 pct CaO. When the sulfur increased over 90 ppm, more CaS-CaO formed just after the addition of calcium, and then the CaS content decreased from over 45 pct to lower than 15 pct and inclusions were mostly Al₂O₃-CaO-CaS and Al₂O₃-CaO with a high Al₂O₃ content. Thermodynamic calculation predicted the variation of the composition of inclusions, indicating good agreement with the measurement, while a certain deviation existed, especially for heats with 90 and 180 ppm sulfur. A reaction model was proposed for the formation of CaO and CaS, which considered the reaction between calcium vapor bubbles in the zone and the dissolved oxygen and sulfur in the molten steel, as described by a Langmuir-type adsorption isotherm with a reaction occurring on the remaining vacant sites. The variation of transient CaS inclusions was discussed based on the thermodynamic calculation and the morphology evolution of typical inclusions containing CaS.     

On Development of Functionally Graded Material Through Fused Deposition Modelling Assisted Investment Casting from Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/SiC Reinforced Waste Low Density Polyethylene

The recycling of packaging materials such as low density polyethylene (LDPE) into useful product is one of the challenging tasks. Since waste LDPE has some issues like low mechanical strength and thermal degradation; some studies have been reported in recent past to improve these properties with ceramic/metallic reinforcements. In this work reusability of LDPE has been ascertained as functionally graded material (FGM) through aluminum (Al) matrix based investment casting (IC). This study highlights the use of SiC and Al₂O₃ as reinforcement in LDPE for IC applications as a novel method for development of FGM. The master patterns for IC were prepared from reinforced LDPE based feed stock filament (prepared on conventional screw extruder) on open source fused deposition modelling setup. The in-house prepared filament wire was subjected to mechanical and thermal testing to ensure recyclability and stability of the material. The photo micrographs and SEM images were collected to ensure the dispersion of SiC and Al₂O₃ reinforcements in Al based FGM.     

Nanostructure Particle-Reinforced Transient Liquid Phase Diffusion Bonding: a Comparative Study

Particle-reinforced aluminum–metal matrix composites (Al-MMCs) are used in many engineering applications, because they provide significant advantages when compared to monolithic aluminum alloys. However, there still exists the need to identify a suitable joining process for these materials, which minimizes particulate disruption and retains the strength of the MMC within the joint region. This study presents a comparison between joint qualities achieved when a monolithic interlayer is used vs when a nanoparticle-reinforced composite interlayer is used during transient liquid phase diffusion bonding of Al-6061 alloy containing 15 vol pct of Al₂O₃ particles. Examination of the joint region using scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS), and X-ray diffraction (XRD) showed the formation of eutectic phases such as Al₃Ni, Al₉FeNi, and Ni₃Si within the joint zone. The results indicate that the addition of nanoparticle reinforcements into the interlayer can be used to improve joint strength and minimize particle segregation.     

Interfacial Reaction Between CaO-SiO2-MgO-Al2O3 Flux and Fe-xMn-yAl (x = 10 and 20 mass pct, y = 1, 3, and 6 mass pct) Steel at 1873 K (1600 °C)

This study investigated the interfacial reaction kinetics and related phenomena between CaO-SiO₂-MgO-Al₂O₃ flux and Fe-xMn-yAl (x = 10 and 20 mass pct, y = 1, 3, and 6 mass pct) steel, which simulates transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) steels at 1873 K (1600 °C). It also examines the effect of changes in the composition of the steel and slag phases on the interfacial reaction rate and the reaction mechanisms. The content of Al and Si in the 1 mass pct Al-containing steel was found to change rapidly within the first 15 minutes of the reaction, but then it remained relatively constant. The content of Al and Si in the 3 to 6 mass pct Al-containing steels, in contrast, changed continuously throughout the entire reaction time. In addition, the content of Mn in the 1 mass pct Al-containing steels initially decreased with increasing time, but the content did not change in the 3 to 6 mass pct Al-containing steels. Furthermore, the mass transfer coefficient of Al, k _Al, in the 1 mass pct Al-containing systems was significantly higher than that in other systems; i.e., the k _Al can be arranged such that 1 mass pct Al systems >> 3 mass pct Al systems ≥ 6 mass pct Al systems. The compositions of the final slags were close to the saturation lines of the [Mg,Mn]Al₂O₄ and MgAl₂O₄ spinels when the slags reacted with 1 mass pct Al and 3 to 6 mass pct Al-containing steels, respectively. These results, which show the effect of Al content on the reaction phenomena, can be explained by the significant increase in the apparent viscosity of the slags that reacted with the 3 to 6 mass pct Al-containing steels. This reaction was likely caused by the precipitation of solid compounds such as MgAl₂O₄ spinel and CaAl₄O₇ grossite at locally alumina-enriched areas in the slag phase. This analysis is in good accordance with the combination of Higbie’s surface renewal model and the Eyring equation.     

Combined Effect of Micro Fillers on the Mechanical and Fracture Behavior of Polyamide 66 and Polypropylene (PA66/PP) Blend

The combinative effect of Micro fillers on the 80/20 wt% of Polyamide 66 and Polypropylene blend (PA66/PP) is studied. Three composites prepared by reinforcing micro fillers of Molybdenum disulphide (MoS₂) (PA66/PP/MoS₂), Silicon carbide (SiC) (PA66/PP/MoS₂/SiC) and Alumina (Al₂O₃) (PA66/PP/MoS₂/SiC/Al₂O₃) of, having different geometric shapes. The mechanical properties studied are tensile strength, flexural strength, impact strength including the hardness of the blend micro composites as per ASTM methods. The fracture toughness at different temperatures of the composites is studied as per ASTM. Results reveal that the combined effect of hybrid micro fillers decreases the mechanical behavior of PA66/PP blend composites. The poorest mechanical properties are obtained when SiC is incorporated into the MoS₂ filled blend PA66/PP composites. The appreciable increase in the mechanical properties is noticed by the addition of Al₂O₃ into the hybrid filled PA66/PP blend composites. Though the effect of SiC addition to PA66/PP/MoS₂ composites increases the impact strength appreciably but decreasing trend is also observed due to the hybrid effect of three fillers. But the differently shaped micro fillers exhibit a synergic effect on the tensile and flexure properties of PA66/PP based composites respectively. The density of the studied blend increases due to denser nature of micro fillers. The hardness of the blend is increased by 18 % by the addition of micro fillers as against the blend PA66/PP. The increase in fracture toughness by 188 % is exhibited by the hybrid effect of micro fillers as against the neat blend at room temperature. Among these micro composites, PA66/PP/MoS₂/SiC/Al₂O₃ has shown superior mechanical properties when compared to individual effect of the fillers on the blend. The fractured surfaces are studied by using scanning electron microscope photographs.