Abstract
The elevated temperature ductility of rapidly solidified 7091 powder metallurgy aluminium alloy was investigated in the temperature range 523–773 K, employing differential strain rate and constant crosshead speed tensile tests. The maximum strain rate sensitivity m attained is less than 0·3, despite the fine initial grain size of the alloy, and a maximum tensile ductility of 190% is obtained. The observed low m value and tensile ductility are attributed to the partially recrystallised microstructure and the preferential distribution of fine oxide particles. Dynamic grain growth at temperatures near 773 K may also restrict the tensile ductility. Irrespective of the test temperature and strain rate the alloy exhibits intergranular failure. Although the alloy does not respond to static recrystallisation, it seems possible to design a processing schedule aimed towards improving rate sensitivity of the flow stress and tensile ductility.
MST/1759
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