Machinability of cenosphere particulate–reinforced AA6061 aluminium alloy prepared by compocasting

Abstract

Cenosphere fly ash particles as waste by-product of gas thermal power plant are successfully incorporated into AA6061 aluminium alloy by improved wettability casting process called compocasting technique to enlarge the application barrier of existing advanced metal matrix composites due to their high fabrication cost. Thereafter, microstructure, interface and composition of the prepared composites were analysed from the X-ray diffraction analysis patterns and scanning electron microscopy equipped with energy-dispersive X-ray techniques. Furthermore, machinability characteristics were identified by wire electrical discharge machining to explore the co-relations among the machining variables and the performance measures such as cutting rate, kerf width and surface roughness for the prepared composites by varying one parameter at a time and keeping the other parameters as constant. The morphological study reveals that there is a uniform distribution of fly ash particles in aluminium matrix phase without formation of any intermetallic compound caused by interfacial reaction. The machinability study indicates that pulse-on-time and pulse-off-time are the most significant process variables that affect the machining performance of the prepared composites. However, wire feed is found to impose the least significant effect among the three process parameters. Also, the neat AA6061 aluminium alloy (0% AA6061/cenosphere composites) exhibited superior machining performance compared to both the reinforced composites (4% and 8%) at similar machining conditions.