DEFORMATION BEHAVIOUR OF ALUMINIUM ALLOY AA6061-10 FLY ASH COMPOSITES FOR AEROSPACE APPLICATION

摘要

Aluminum fly ash metal matrix composites (MMCs) find important applications in aerospace where specific stiffness is important. The aluminum fly ash metal matrix composites (ALFA) can be processed through low cost processing route ie by liquid metallurgy - stir casting . These ALFA composites have limited ductility which makes secondary mechanical processing very difficult, the strain rate and temperature for deformation processing is generally set by trial and error methods. The development of processing maps for the optimization of processing parameters such as strain rate and temperature has been found to be very useful, The aim of the present investigation is to study the constitutive flow behavior of AA6061 aluminum alloy-10 vol. % fly ash particulate MMC under hot-working conditions and to generate a processing map for optimization of hot workability. The mechanical response of AA6061 aluminum fly ash metal matrix composite was investigated by means of hot compression tests. The flow stress curves were obtained in the temperature and strain rate ranges of 200-500 ℃ and 0.5-0.01 s~(-1), respectively in order to obtain the processing and stability maps. The different domains in the processing maps may be correlated with specific micro structural mechanisms and the "safe" mechanisms were chosen for processing. The hot deformation behavior of the matrix material AA6061 was also evaluated for the purpose of comparison with that of the aluminum fly ash metal matrix composites. All the zones of flow instability , micro structural and failure mechanisms involved in the hot working of the MMC were studied by optical microscope and scanning electron microscope.