Abstract: A new precedure to prepare ultra-high strength aluminum alloy was proposed. The procedure is carried out through subjecting the aluminum alloy pre-heated at solid solution treatment temperature to the large strain deformation (equalchannel angular pressing, i.e. ECAP) with appropriately quick cooling of the alloy. This approach can process low ductility aluminum alloy and has the potential of adding dislocation strengthening and other strengthening together to significantly strengthen the alloy. The experimental results show that the ECAP-resulted strengthening for the 7085 Al alloy preheated at solid solution treatment temperature is related with the temperature of the used ECAP die. Compared to the ECAP proceesing with the ECAP die temperature of 400 °C, the ECAP proceesing with the ECAP die temperature at room temperature leads to a considerable increase in strengthening. The theorical calculation based on Taylor equation on strength dislocation density relationship indicates that the dominant factor for leading to the considerable increase in strengthening is not dislocation strengthening increase, but other strengthening mechanisms that are believed to be precipitation strengthening and grain boundary/subgrain boundary strengthening.
 

Key words: ultra-high strength Al alloy, large strain deformation, strengthening mechanism