IN-SITU ALUMINIUM MATRIX COMPOSITES BY HYBRID PROCESS

Abstract

The conventional alloys have certain drawbacks which arises the need of the engineering sectors to look for materials which can deliver such properties which are hard to obtain from the conventional alloys. The most potential material which cater that requirement of various engineering sectors are aluminium matrix composites (AMMCs). AMMCs have more benefits compared to conventional alloys. Different processing techniques to obtain the AMMCs are there such as powder metallurgy and liquid metallurgy but the latter technique have an advantage or edge over the first one because of its easy fabrication and its cost effectiveness for large size components. The governing factors for the selection of material and fabrication process are shape and size of the component, cost, ease of fabrication, distribution and wettability between the reinforcement phase and matrix alloy. It has been over a half of century since ultrasonic processing of materials have been used. It possesses the quality of environmental favouring, effectiveness from view of economy, and can be combined with other processing techniques. It superbly scatters the reinforcement particles in the molten alloy. Agglomeration of reinforcement particles in the composites are not much after the use of ultrasonic processing as it breaks the big and the medium kind of clusters into small clusters of reinforcement particles. The applications of AMMCs are in making of components, e.g., automobile components (like casings, brake drum, equipments of mining, head light combos,etc.), tennis racket and structural application components. As AMMCs have the feature of reduced strength to weight ratio, stiffness and energy efficiency, they often act as the replacement of either Al-alloy products or cast-iron products. The automobile, railway and aerospace sectors are the major sectors where they find their use to the most. In the present study, the investigation of the ultrasonication effect in various aluminium matrix composites have been carried out. The composites were fabricated by employing different conditions like in one case we added 1 wt% Ce02 powder in molten alloy and in another case 1.5 wt% Ce02 powder in molten alloy. We also prepared composites by going one step ahead after addition of 1 wt% Ce02 or 1.5 wt% Ce02 powder by It introducing the ultrasonication process. Hardness comparisons and tensile strength comparisons between the samples casted at above stated conditions were done. The sample ultrasonically treated was found to have higher hardness than the samples not been ultrasonically treated. Regarding porosity, observation of porosity were high in those samples which had not given ultrasonic treatment. A1203 particles were observed by XRD analysis but not with EDAX analysis. The 0.2 % proof stress, UTS and elongation were on increase with increase in reinforcement content and with introduction of ultrasonic treatment. The dissertation includes five chapters in which Chapter 1 gives the brief introduction about metal matrix composite (MMCs), aluminium matrix composite (AMMCs), their processing techniques, ultrasonic processing and the objective of the report. Chapter 2 gives theoretical background of ultrasonic processing of various composites and work of previous researchers related to this field. Chapter 3 discusses about the experimental methodology used for this dissertation work. Chapter 4 discusses the results which are obtained by conducting different experiments. Chapter 5 gives the conclusions of the overall work of dissertation. References are given at the end of the dissertation.