CHARACTERISTICS OF SUPERPLASTICITY DOMAIN IN THE PROCESSING MAP FOR HOT-WORKING OF AN AL-ALLOY 2014-20VOL-PERCENT-AL2O3 METAL-MATRIX COMPOSITE

The processing map for hot working of Al alloy 2014-20vol.%Al2O3 parti culate-reinforced cast-plus-extruded composite material has been gener ated covering the temperature range 300-500 degrees C and the strain r ate range 0.001-10 s(-1) based on the dynamic materials model. The eff iciency eta of power dissipation given by 2m/(m + 1), where m is the s train rate sensitivity, is plotted as a function of temperature and st rain rate to obtain a processing map. A domain of superplasticity has been identified, with a peak efficiency of 62% occurring at 500 degree s C and 0.001 s(-1). The characteristics of this domain have been stud ied with the help of microstructural evaluation and hot-ductility meas urements. Microstructural instability is predicted at higher strain ra tes above (ls(-1)) and lower temperatures (less than 350 degrees C).