DEVELOPMENT AND CHARACTERIZATION OF HYBRID ALUMINIUM METAL MATRIX COMPOSITES FOR FATIGUE/ WEAR RESISTANT APPLICATIONS

Abstract

Aluminium metal matrix composites (AMMCs) are considered to be new generation potential materials for numerous engineering applications due to their augmented mechanical and physical characteristics. Though, conventional aluminium based composites exhibit enhanced attributes as compared to the unreinforced aluminium alloys, but at the cost of some specific mechanical characteristics which are essential to prevent premature failure of any mechanical component under in service stress. In process of surmounting this issue, fabrication of hybrid composites with reduced interfacial area and reduced meniscus penetration defect is being encouraged in order to adopt them as more dependable and extensible materials. An extensive research gap can be observed for development of costeffective and eco-friendly hybrid aluminium composites with augmented characteristics. Past research studies have provided limited literature on some conventional fabrication techniques, with constrained reinforcement combinations and higher reinforcement contents. Influences of various reinforcements on a wider range of characteristics of aluminium composites have also not been reported so far. Hence, there was an enormous scope for present research work, involving development and assessment of economical and environment friendly hybrid aluminium metal matrix composites with upgraded mechanical properties. Present experimental investigation was carried out to synthesize environment friendly (using hazardously disposed hen eggshells as one of the reinforcements) and cost-effective (maximum total reinforcement content of 5.5% only) hybrid aluminium metal matrix composites through electromagnetic stir casting technique. Al7075-T6 alloy was infused with; eggshell particles (wt.% 0.5, 1and 1.5, particle size ~ 60 µm), silicon carbide particles (wt.% 1, 1.5 and 2, particle size ~ 65 µm) and aluminium oxide particles (wt.% 1.5, 2 and 2.5, particle size ~90 µm) with variable mechanical stirring time (2, 4 and 6 minutes) in accordance with Taguchi’s orthogonal array L9. Synthesized aluminium composites have been examined for microstructural studies and elemental compositions using FESEM, X-ray diffractometry and EDS etc. techniques. Hybrid aluminium metal matrix vii composites have further been evaluated for various physical and mechanical attributes such as density, porosity, residual stress, microhardness, tensile strength, fatigue life, tribology and machinability followed by process parameter optimization through Taguchi approach and ANOVA analysis. With extensively augmented characteristics, synthesized hybrid aluminium composites strongly advocate their applications in automotives, high strength structures and aerospace etc.