Manufacturing methodology on casting-based aluminium matrix composites: systematic review

Ongoing industrial demand for lightweight materials has spiked the research interest in aluminium-based metal matrix composites for its specific properties. The amount of scientific publication available on the matter has led to the vast production of knowledge, which highlights the need for a systematic assessment if further progress is expected. In this paper, a systematic review of the published literature is conducted, according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, on the Scopus and Web of Science databases were used in the literature search, which was completed on the 29 August 2020. The data of the research work is structured in the particle pre-processing stage and the melt processing stage. The present review clarifies the combined pair-wise effect of particles and the melt treatment performed on their wettability or dispersive or de-agglomerative capability, which allows to achieve their final mechanical properties.This work was supported by PTDC/EMEEME/30967/2017 and NORTE-0145-FEDER030967, co-financed by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalization (COMPETE 2020), under Portugal 2020, and by the Fundação para a Ciência e a Tecnologia—FCT I.P. national funds. Also, this work was supported by Portuguese FCT, under the reference project UIDB/04436/2020, Stimulus of Scientific Employment Application CEECIND/03991/2017, research doctoral Grant 2020.08564.BD

Effect of Processing Parameters and Matrix Shrinkage on Porosity Formation During Synthesis of Metal Matrix Composites with Dual-scale Fiber Reinforcements Using Pressure Infiltration Process

This is first such study on porosity formation phenomena observed in dual-scale fiber preforms during the synthesis of metal matrix composites (MMCs) using the gas-based pressure infiltration process (gas PIP). In this thesis, different mechanisms of porosity formation during pressure infiltration of Al-Si alloys into Nextel\u27s 3D woven ceramic-fabric reinforcements (a dual-porosity or dual-scale porous medium) are studied. The effect of processing conditions in terms of the infiltration temperature and pressure on porosity content of the ceramic fabric infiltrated by the alloys through the gas PIP is investigated. Relative density (RD), defined as the ratio of the actual MMC density and the density obtained at ideal 100% saturation of the preform, was used to quantify overall porosity. Increasing the infiltration temperature led to an increase in RD (and reduction in porosity) due to reduced viscosity and enhanced wettability leading to improved feedability of the liquid metal. Similarly, increasing the infiltration pressure led to enhanced penetration of fiber tows and led to higher RD and reduced porosity. For the first time, the modified Capillary number (Ca*), which is found to predict formation of porosity in polymer matrix composites quite well, is employed to study porosity in MMCs made using PIP. It is observed that in the high Ca* regime used in the present study (and common in PIP), the overall porosity shows a strong downward trend with increasing Ca* due to a decrease in the size of trapped air pockets inside fiber tows due to increased infiltration pressures. This contradicts the well-known result of increasing porosity with Ca* observed by Patel et al. in [1]. In addition, the effect of matrix shrinkage on porosity content of the samples is studied through using a zero-shrinkage Al-Si alloy as the matrix: usage of this alloy as the matrix led to a reduction in porosity content

In-situ Al3Ti/Al Verbundwerkstoffe durch Einrühren mit hoher Scherrate: Mikrostruktur und mechanische Eigenschaften

The reduction of emissions of CO2 generated by vehicles according to the regulation of the EU drives the decrease of car weight. Therefore, high specific stiffness, strength and excellent fracture toughness of new structural materials are desirable. Recently, particle reinforced Al matrix composites (PAMCs) have attracted much attention since they combine the good ductility of the Al matrix with the high Young’s modulus and strength from the reinforcements. However, the main limitations to the application of PAMCs on a large scale in industry are the quite high production costs and their low ductility. The low ductility of current PAMCs can be attributed to the poor interface bonding between the reinforcement and the Al matrix and to an inhomogeneous particle distribution. Therefore, the aim of this work was to develop a highly efficient and low cost fabrication method for preparing PAMCs with a uniform particle distribution and excellent interface bonding. In this work, the intermetallic phase Al3Ti formed by the reaction between Ti powder and Al melt was used as reinforcement of the Al matrix due to its high Young’s modulus, strength, hardness and low density. A melt stirring method was applied for preparing Al3Ti/Al composites with a rotor stator high shear mixer combined with permanent mold casting. Firstly, the effect of a conventional mixer and the high shear mixer on the microstructure of the Al3Ti/Al composites was investigated. Subsequently, various Ti particles were investigated to select the optimal starting material for preparing Al3Ti/Al composites, followed by the investigation of different processing parameters. Thus, Al3Ti/Al composites with high particle contents could be produced and the microstructures and mechanical properties were characterized. The results show that in situ Al3Ti/Al composites can be successfully prepared via the reaction between Ti particles and Al melt using a rotor stator high shear mixer. Compared to a conventional mixer, the reaction rate and homogeneity of reinforcing particles are significantly improved. Hydrogen dehydrogen (HDH) Ti powder is the preferable raw material due to a lower price and a higher reaction rate compared to gas atomized Ti powder. The higher reaction rate can be attributed to the higher specific surface of HDH Ti particles. Furthermore, the fine Ti powder is more appropriate as staring material for preparing Al3Ti/Al composites compared to the coarse Ti powder due to the shorter reaction time. Additionally, an intermediate mixing speed is reasonable during the fabrication process since a lower mixing speed cannot solve the issue of particle agglomerations, which leads to a significant reduction of ductility of the Al3Ti/Al composite. Furthermore, a higher mixing speed leads to the severe air entrainment, and the homogeneity of particle distribution is similar to that produced with the intermediate mixing speed. The mechanical properties are enhanced obviously due to the refined grains of the Al matrix (a side effect of the formed Al3Ti particles) and the presence of reinforcing Al3Ti particles, which can be attributed to the homogeneous distribution of Al3Ti particles and the strong interface bonding between Al3Ti particles and Al matrix.Die Reduzierung der CO2 Emissionen von Fahrzeugen gemäß der EU Verordnung treibt die Verringerung des Fahrzeuggewichts an. Dafür sind neue Strukturwerkstoffe mit hoher spezifischer Steifigkeit, Festigkeit und ausgezeichneter Bruchzähigkeit erforderlich. In jüngster Zeit haben partikelverstärkte Al Matrix Composite (PAMCs) viel Aufmerksamkeit erregt, da diese Verbundwerkstoffe die gute Duktilität der Al Matrix mit dem hohen Elastizitätsmodul und der Festigkeit der Verstärkungsphase kombinieren. Die Haupteinschränkungen für die Anwendung von PAMCs in der Industrie in großem Maßstab sind jedoch die recht hohen Produktionskosten und ihre geringe Duktilität. Die geringe Duktilität der aktuellen PAMCs ist auf eine schlechte Grenzflächenanbindung zwischen Verstärkungsphase und Al Matrix und die inhomogene Partikelverteilung zurückzuführen. Ziel der Arbeiten war es daher, ein hocheffizientes und kostengünstiges Herstellungsverfahren zur Herstellung von PAMCs mit einer homogenen Partikelverteilung und exzellenter Grenzflächenbindung zu entwickeln. In dieser Arbeit wurde die intermetallische Phase Al3Ti, die durch die Reaktion zwischen Ti Pulver und Al Schmelze in situ gebildet wird, als Verstärkung der Al Matrix verwendet, da sie einen hohen Elastizitätsmodul, hohe Festigkeit, hohe Härte und niedrige Dichte aufweist. Zur Herstellung der Al3Ti/Al Verbundwerkstoffe wurde das Schmelzrührverfahren unter Verwendung eines High Shear Mixers (Rotor Stator System) in Verbindung mit dem Kokillenguss angewendet. Zunächst wurden die Vorteile des High Shear Mixers gegenüber konventionellen Mixern herausgearbeitet. Danach wurden verschieden Ti Pulver betrachtet, um das am besten geeignete Ausgangsmaterial für die Herstellung von Al3Ti/Al Verbundwerkstoffen auszuwählen, schließlich wurde die Auswirkung unterschiedlicher Prozessparameter untersucht. Unter Verwendung geeigneter Prozessparameter wurden Al3Ti/Al Verbundwerkstoffe mit steigendem Partikelgehalt hergestellt und die Mikrostrukturen charakterisiert und mechanischen Eigenschaften ermittelt. Die Ergebnisse zeigen, dass in situ Al3Ti/Al Composite durch die Reaktion zwischen Ti Pulver und Al Schmelze mit dem High Shear Mixer erfolgreich hergestellt werden können. Durch Verwendung des High Shear Mixers konnten die Reaktionsrate und die Homogenität der Partikelverteilung signifikant erhöht werden. Das hydrogen dehydrogen (HDH) Ti Pulver ist aufgrund des niedrigeren Preises und der höheren Reaktionsgeschwindigkeit im Vergleich zu gaszerstäubtem Ti Pulver das bevorzugte Pulver als Ausgangsmaterial. Die höhere Reaktionsgeschwindigkeit ist auf die höhere spezifische Oberfläche des HDH Ti Pulvers zurückzuführen. Darüber hinaus ist feineres Ti Pulver aufgrund der kürzeren Reaktionszeit und der kleineren Endgröße der gebildeten Al3Ti Partikel besser für die Herstellung von Al3Ti/Al Verbundwerkstoffen geeignet. Eine optimale Rührgeschwindigkeit wurde gefunden. Bei niedrigeren Mischgeschwindigkeiten besteht das Problem der Partikelagglomerationen, was zu einer deutlichen Reduzierung der Duktilität des Al3Ti/Al Verbunds führt. Eine höhere Rührgeschwindigkeit hingegen führt zu starken Lufteinwirbelungen und somit zu einer hohen Porosität im Gussteil. Die Homogenität der Partikelverteilung zeigt dabei keine Veränderung. Die mechanischen Eigenschaften werden durch die Kornfeinung in der Al Matrix (einem Nebeneffekt der Al3Ti Partikel) und die homogene Verteilung der verstärkenden Partikel deutlich verbessert. Die Al3Ti/Al Verbundwerkstoffe zeigen ein duktiles Bruchverhalten, was sich auf die homogene Verteilung der Al3Ti Partikel und die starke Grenzflächenbindung zwischen Al3Ti Partikeln und Al Matrix zurückführen lässt

Casting and Applications of Functionally Graded Metal Matrix Composites

This chapter discusses the concepts, casting techniques and applications of functionally graded materials metal matrix composites (FGMMCs). Considerations were given to bulk functionally graded aluminium matrix composites (FGAACs) production processes. Liquid-metal forging processes of FGAACs fabrication, such as infiltration process, squeeze casting, friction casting or compocasting, stir, and centrifugal casting were discussed. The chapter provides basic concepts of the processes and overview of their processing parameters, such as mould rotational speed; reinforcement particles size and volume; degassing method; melting and pouring temperatures; pressure; and stirrer. The study notes that functionally graded materials (FGMs) are commonly used in automotive, aircraft, aviation, chemical, medical, engineering, renewable energy, nuclear energy, and optics electronics industries

In-situ Al3Ti/Al composites produced by high shear technology: microstructure and mechanical properties

Die Reduzierung der CO2 Emissionen von Fahrzeugen gemäß der EU Verordnung treibt die Verringerung des Fahrzeuggewichts an. Dafür sind neue Strukturwerkstoffe mit hoher spezifischer Steifigkeit, Festigkeit und ausgezeichneter Bruchzähigkeit erforderlich. In jüngster Zeit haben partikelverstärkte Al Matrix Composite (PAMCs) viel Aufmerksamkeit erregt, da diese Verbundwerkstoffe die gute Duktilität der Al Matrix mit dem hohen Elastizitätsmodul und der Festigkeit der Verstärkungsphase kombinieren. Die Haupteinschränkungen für die Anwendung von PAMCs in der Industrie in großem Maßstab sind jedoch die recht hohen Produktionskosten und ihre geringe Duktilität. Die geringe Duktilität der aktuellen PAMCs ist auf eine schlechte Grenzflächenanbindung zwischen Verstärkungsphase und Al Matrix und die inhomogene Partikelverteilung zurückzuführen. Ziel der Arbeiten war es daher, ein hocheffizientes und kostengünstiges Herstellungsverfahren zur Herstellung von PAMCs mit einer homogenen Partikelverteilung und exzellenter Grenzflächenbindung zu entwickeln. In dieser Arbeit wurde die intermetallische Phase Al3Ti, die durch die Reaktion zwischen Ti Pulver und Al Schmelze in situ gebildet wird, als Verstärkung der Al Matrix verwendet, da sie einen hohen Elastizitätsmodul, hohe Festigkeit, hohe Härte und niedrige Dichte aufweist. Zur Herstellung der Al3Ti/Al Verbundwerkstoffe wurde das Schmelzrührverfahren unter Verwendung eines High Shear Mixers (Rotor Stator System) in Verbindung mit dem Kokillenguss angewendet. Zunächst wurden die Vorteile des High Shear Mixers gegenüber konventionellen Mixern herausgearbeitet. Danach wurden verschieden Ti Pulver betrachtet, um das am besten geeignete Ausgangsmaterial für die Herstellung von Al3Ti/Al Verbundwerkstoffen auszuwählen, schließlich wurde die Auswirkung unterschiedlicher Prozessparameter untersucht. Unter Verwendung geeigneter Prozessparameter wurden Al3Ti/Al Verbundwerkstoffe mit steigendem Partikelgehalt hergestellt und die Mikrostrukturen charakterisiert und mechanischen Eigenschaften ermittelt. Die Ergebnisse zeigen, dass in situ Al3Ti/Al Composite durch die Reaktion zwischen Ti Pulver und Al Schmelze mit dem High Shear Mixer erfolgreich hergestellt werden können. Durch Verwendung des High Shear Mixers konnten die Reaktionsrate und die Homogenität der Partikelverteilung signifikant erhöht werden. Das hydrogen dehydrogen (HDH) Ti Pulver ist aufgrund des niedrigeren Preises und der höheren Reaktionsgeschwindigkeit im Vergleich zu gaszerstäubtem Ti Pulver das bevorzugte Pulver als Ausgangsmaterial. Die höhere Reaktionsgeschwindigkeit ist auf die höhere spezifische Oberfläche des HDH Ti Pulvers zurückzuführen. Darüber hinaus ist feineres Ti Pulver aufgrund der kürzeren Reaktionszeit und der kleineren Endgröße der gebildeten Al3Ti Partikel besser für die Herstellung von Al3Ti/Al Verbundwerkstoffen geeignet. Eine optimale Rührgeschwindigkeit wurde gefunden. Bei niedrigeren Mischgeschwindigkeiten besteht das Problem der Partikelagglomerationen, was zu einer deutlichen Reduzierung der Duktilität des Al3Ti/Al Verbunds führt. Eine höhere Rührgeschwindigkeit hingegen führt zu starken Lufteinwirbelungen und somit zu einer hohen Porosität im Gussteil. Die Homogenität der Partikelverteilung zeigt dabei keine Veränderung. Die mechanischen Eigenschaften werden durch die Kornfeinung in der Al Matrix (einem Nebeneffekt der Al3Ti Partikel) und die homogene Verteilung der verstärkenden Partikel deutlich verbessert. Die Al3Ti/Al Verbundwerkstoffe zeigen ein duktiles Bruchverhalten, was sich auf die homogene Verteilung der Al3Ti Partikel und die starke Grenzflächenbindung zwischen Al3Ti Partikeln und Al Matrix zurückführen lässt.The reduction of emissions of CO2 generated by vehicles according to the regulation of the EU drives the decrease of car weight. Therefore, high specific stiffness, strength and excellent fracture toughness of new structural materials are desirable. Recently, particle reinforced Al matrix composites (PAMCs) have attracted much attention since they combine the good ductility of the Al matrix with the high Young’s modulus and strength from the reinforcements. However, the main limitations to the application of PAMCs on a large scale in industry are the quite high production costs and their low ductility. The low ductility of current PAMCs can be attributed to the poor interface bonding between the reinforcement and the Al matrix and to an inhomogeneous particle distribution. Therefore, the aim of this work was to develop a highly efficient and low cost fabrication method for preparing PAMCs with a uniform particle distribution and excellent interface bonding. In this work, the intermetallic phase Al3Ti formed by the reaction between Ti powder and Al melt was used as reinforcement of the Al matrix due to its high Young’s modulus, strength, hardness and low density. A melt stirring method was applied for preparing Al3Ti/Al composites with a rotor stator high shear mixer combined with permanent mold casting. Firstly, the effect of a conventional mixer and the high shear mixer on the microstructure of the Al3Ti/Al composites was investigated. Subsequently, various Ti particles were investigated to select the optimal starting material for preparing Al3Ti/Al composites, followed by the investigation of different processing parameters. Thus, Al3Ti/Al composites with high particle contents could be produced and the microstructures and mechanical properties were characterized. The results show that in situ Al3Ti/Al composites can be successfully prepared via the reaction between Ti particles and Al melt using a rotor stator high shear mixer. Compared to a conventional mixer, the reaction rate and homogeneity of reinforcing particles are significantly improved. Hydrogen dehydrogen (HDH) Ti powder is the preferable raw material due to a lower price and a higher reaction rate compared to gas atomized Ti powder. The higher reaction rate can be attributed to the higher specific surface of HDH Ti particles. Furthermore, the fine Ti powder is more appropriate as staring material for preparing Al3Ti/Al composites compared to the coarse Ti powder due to the shorter reaction time. Additionally, an intermediate mixing speed is reasonable during the fabrication process since a lower mixing speed cannot solve the issue of particle agglomerations, which leads to a significant reduction of ductility of the Al3Ti/Al composite. Furthermore, a higher mixing speed leads to the severe air entrainment, and the homogeneity of particle distribution is similar to that produced with the intermediate mixing speed. The mechanical properties are enhanced obviously due to the refined grains of the Al matrix (a side effect of the formed Al3Ti particles) and the presence of reinforcing Al3Ti particles, which can be attributed to the homogeneous distribution of Al3Ti particles and the strong interface bonding between Al3Ti particles and Al matrix

The production of metal matrix composites using the stir casting technique

The fabrication of Metal Matrix Composites (MMCs) using the stir casting technique is the focus of this study. A significant part of the work consists of the design of a specialised rig for this high temperature processing method. Following preliminary tests, graphite was chosen as the mam vessel material, and a crucible was designed with a bottom pouring mechanism. In order to optimise stirring conditions, a computer program was used to stimulate the fluid flow in the process crucible. The mam research challenge was to solve the problem o f poor wettability between particulate SiC and molten aluminium (A359 alloy), materials which are potentially suitable to the proposed fabrication approach as reinforcement and matrix materials respectively. The percentages of SiC particles used were m the range o f 5 to 25 volume percent, samples were cast into ingot or tensile specimen, and some samples were heat treated by precipitation hardening with T6 artificial ageing. It was found that the both increasing the silicon carbide content, and T6 artificial treatment increase the mechanical properties such as hardness and tensile strength of the matrix alloy. Charactenzation of the MMCs produced included observation of microstructure, porosity content measurement, tensile strength, microhardness, and compression strength measurements. The fabrication approach was successful in producing cast MMCs samples which have reasonable mechanical properties The use of clean SiC particles, magnesium as a wetting agent, and continuous stirring while the MMC slurry is solidifying were found to promote the wettability o f SiC and A359 matrix alloy Decreasing the solidifying time was found to improve the wettability significantly

Solidification behaviour and mechanical properties of cast Mg-alloys and Al-based particulate metal matrix composites under intensive shearing

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Magnesium alloys, as the lightest of all structural metallic materials, and aluminium-based particulate metal matrix composites (PMMCs), offering unified combination of metallic and ceramic properties, have attracted increased interest from the automotive, aerospace, electronic and recreation industries. Current processing technologies for PMMCs do not achieve a uniform distribution of fine-sized reinforcements and produce agglomerated particles in the ductile matrix, which are detrimental to the ductility. At the same time, molten magnesium alloys contain impurities and oxides and when cast conventionally, the final components usually exhibit a coarse and non-uniform microstructure with various casting defects. The key idea in this thesis has been to adopt a novel intensive melt conditioning process, allowing the application of sufficient shear stress that would disperse solid particles present in the melt and offer unique solidification behaviour, improved fluidity and die-filling during casting. The Melt Conditioned High Pressure Die Casting (MC-HPDC) process, where intensive shearing is directly imposed on the alloy melt, which is then cast by the conventional HPDC process, has been used to produce PMMC and magnesium alloy castings. The MC-HPDC process for PMMCs leads to a uniform dispersion of the reinforcement in the matrix, confirmed by quantitative statistical analysis, and increased mechanical performance as indicated by an increase in the hardness and the tensile properties of the composites. We describe a solidification path for aluminium containing magnesium alloys, where intensive shearing prior to casting leads to effective dispersion of solid oxide particles, which then effectively act as nucleation sites for magnesium grains, resulting in significant grain refinement. The MC-HPDC processed magnesium castings have a significantly refined microstructure, with reduced porosity levels and casting defects. Evaluation of the mechanical properties of the castings reveals the beneficial effect of intensive shearing. After careful optimization, the MC-HPDC process shows promising potential for the direct recycling of high purity magnesium die casting scrap, producing casting with mechanical properties comparable to those of primary magnesium alloys

Ceramic particles reinforced copper matrix composites manufactured by advanced powder metallurgy: Preparation, performance, and mechanisms

Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties, thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity. This greatly expands the applications of copper as a functional material in thermal and conductive components, including electronic packaging materials and heat sinks, brushes, integrated circuit lead frames. So far, endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix. This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles, including ceramic particle content, size, morphology and interfacial bonding, on the diathermancy, electrical conductivity and mechanical behavior of copper matrix composites. The corresponding models and influencing mechanisms are also elaborated in depth. This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites. By more precise design and manipulation of composite microstructure, the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields

Casting of particle reinforced metal matrix composite by liquid state fabrication method: A review

The purpose of this study is to investigate the characterization of Metal Matrix Composite (MMC), using liquid state fabrication technique. The paper also considered the latest trend of MMC. The selection of the matrix and reinforcement is an essential component in the production of outstanding composite materials. These materials are used to improve the ultimate strength, hardness, fatigue behaviours, creep quality, machinability, weld ability, fracture toughness, wear resistance capacity, and other properties of the composite material. In recent years, aluminium-based metal matrix composite has emerged as a leading class of material due to the exceptional qualities it has. It has been observed, that the metal matrix composite that is produced is highly influenced by both the controlled and uncontrolled elements that are involved in the stir-casting process

Composite and nanocomposite metal foams

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