Papers by Keyword: Aluminum Matrix Composites

Abstract: The sintering behavior of spark plasma sintering was analyzed by extracting features from process data obtained during the fabrication of aluminum matrix composites and machine learning using the obtained features were performed to predict relative density of composites. Seventy-five samples were sintered with different types of reinforcement, and different temperature and pressure conditions. Regression methods include linear regression such as Ridge, Lasso and Elastic Net, and nonlinear regression such as random forest, gradient boosting and XGBoost were tested. XGBoost had the highest prediction accuracy and the trained model was used for Shapley additive explanations value analysis and inverse analysis.

Abstract: By replacing the interface with sharp change properties with a functionally graded material with a gradually changing composition, a stable interface can be formed for mechanical and functional properties. In this study, the final goal is to functionally grade the interface between aluminum and alumina (Al₂O₃)/aluminum (Al) composites. First, the segmentation velocity of Al₂O₃ particles under gravity was measured to clarify the possibility of functional grading. The starting materials used were A356.0 Al alloy and α-type Al₂O₃ particles. The segmentation velocity obtained by the experiment was much faster than the theoretical velocity obtained by Stokes' law. It seems Stokes' law assumes that the particles are spherical and there is no interaction between particles, but the actual particle velocity was affected by the actual particle shape and interaction between particles. These factors affect the change in the segmentation velocity. The height of the mold was set to 40 mm, and an Al₂O₃ particle/Al composite with a particle size of 6.7 μm was placed on the top and an Al alloy was placed on the bottom in the mold, melted, and rapidly solidified after 12 sec., and an Al₂O₃ particle-dispersed Al alloy functionally graded composite was obtained under gravity.

Abstract: A method of synthesizing dispersion-strengthened aluminum matrix composites using a powder metallurgical technique and an in situ method was considered. Methods combination was aimed at ensuring energy efficiency, avoiding vacuum treatment of the reaction medium, and using inert gasses to protect from oxidation. Reinforcement phase precursors are capable of ensuring good wettability of dispersed particles by the molten matrix metal. The options of the methods’ practical implementation are presented by the example of producing aluminum matrix composites filled with various functional particles.

Abstract: The effect of segregation defect of SiC particles on the properties of materials was studied. 15% SiCp/2009Al composites were prepared by powder metallurgy (PM). Special SiC/Al samples were added to 15% SiCp/2009Al composites. These SiC/Al samples with different sizes and volume fractions were 25%, 35%, 45% and 60%, respectively, which resulted in SiC particulates segregation defect. The 15% SiCp/2009Al composites with defects were tested by ultrasonic testing. Tensile samples were obtained at the locations, where defects might be detected and the mechanical properties were tested. The results showed that all defective samples were cracked at the defective location. The difference in tensile strength between the samples of defect and the samples without defect was large. The toughness of the sample containing the defect reduced and the brittleness increased. The dimples on the matrix indicate that ductile fracture occurred during the fracture process. The cleavage fracture or cracking of the SiC particulates indicated that the stress can be effectively transferred from the matrix to the particles, and the particulates strengthen the matrix well. However, the sample with defect led to brittle fracture in the defect, and a crack source produced at the interface, resulting in a significant decrease in the mechanical properties of the material. If the inhomogeneous distribution of particulate containing a large area was found in the ultrasonic testing of the aluminum matrix composites, the tensile properties of the products generally cannot meet the requirement for application.

Abstract: This work concerns microstructure and mechanical properties investigations of aluminum based composite strengthened with the TiC particles being in nanometer size. The composites were fabricated by the casting method combined with in-situ formation of TiC particles. Applying a suitable composition of components and moderators of SHS reaction which occur during casting, it was possible to cast the samples with TiC particles of size of 150 nm and faceted shape. Microstructure investigations using scanning and transmission electron microscopy (SEM and TEM) allowed to identified the distribution of TiC particles and their preferred location in the microstructure of composites. Also the additional precipitates with different size and shape were identified in investigated samples. Significant increase of strength was observed in in-situ cast composites in comparison to Al-1000 alloy mainly due mainly due to coefficient of thermal expansion and elastic modulus mismatch between the reinforcements and the metal matrix, Hall-Pecht relation and also in minority the Orowan effect.

Abstract: In the past 20 years, the development of aluminum matrix composites (AMCs) has made a qualitative leap. This article comprehensively introduces the performance characteristics and the preparation methods of aluminum matrix composites. The powder metallurgy method (P/M) is elaborated in detail. And the applications of aluminum matrix composites in aerospace, automobile and other fields are described. Finally, the future development of aluminum matrix composites is prospected.

Abstract: The paper describes the advantages and prospects of using the physical methods of melts processing in the production of aluminum alloys and cast aluminum matrix composites. Classification of the physical methods of the melt processing by the state of metal during the processing period and by the physical principle of the imposed effects is proposed. The influence of physical processing of melts on the structure of aluminum matrix composites depending on the type of imposed influence and the origin of the reinforcing phases is shown. The positive effect of thermo-temporal treatment on the structure of materials was confirmed on example of in-situ composites of Al-Mg₂Si system, it includes reduction in the average size of endogenous reinforcing phases and changing their morphology to a more compact.

Abstract: In the present paper aluminum matrix composites were fabricated using base material AA6082-T6. SiC and B₄C particulates were used as reinforcement to obtain hybrid and non-hybrid composites through the conventional stir casting process. AA6082-T6/SiC composites with 5, 10, 15 and 20 wt % of SiC; AA6082-T6/B₄C composites with 5, 10, 15 and 20 wt % of B₄C and AA6082-T6/(SiC+B₄C) hybrid composites with 5, 10, 15 and 20 wt % of (SiC+B₄C) taking equal fraction of SiC and B₄C were made and the microstructure study was carried out. X-Ray diffraction (XRD) patterns revels the presence of reinforcement within the matrix along with some other compounds. The microstructure of the fabricated composites was examined with the help of Scanning electron microscope (SEM) and the micrographs revealed that the dispersion of reinforced particles was reasonably uniform at all weight percentages.

Abstract: Aluminium matrix composites (AMCs) consisting of high-strength, age-hardenable aluminium alloys and homogeneously dispersed hard particles open up new possibilities in designing light-weight material based security related structures. The susceptibility of the matrix alloy to selective corrosion can be reduced significantly by anodic oxidation. A powder-metallurgical processed alloy AlCu4MgMn with hard particles and a commercial wrought alloy for reference were used for the investigations.In order to control the microstructure of anodic aluminium oxide (AAO) formed on AMCs, it is necessary to understand the formation mechanism and the influencing parameters. Therefore in a first run, the anodizing behaviour of matrix alloy was separated from the behaviour of hard particles. The AAO coatings show small growth rates on the matrix and the reference alloy accompanied by a complex pore structure which differs from the ordered vertical pore structure on pure aluminium. Depending on the type and the size as well as the anodizing parameters, the particles are either incorporated into the AAO coating unchanged or partly resp. completely oxidized. The AAO microstructure changes significantly in dependence of the anodizing parameters. It is shown that a technically relevant coating thickness can be achieved on AMCs by choosing appropriate process parameters.

Abstract: According to the basic principles of electromagnetism, the magnetic flux density on the surface of the metal melt was calculated by numerical simulation method. The relational expression of the electromagnetic body force and the magnetic flux density was deduced. The results show that the electromagnetic body force in the melt is directly proportional to the square of the magnetic induction intensity. Increasing the electric current, the electromagnetic body force in the melt can be increased effectively. Increasing the frequency, the particular electromagnetic body force within the melt can be increased first and then decreased.