THE ROLE OF HOT-WORKING ON THE MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF THE L12-TYPE MANGANESE-MODIFIED AL3TI ALLOY

The crystal structure of a manganese-modified Al3Ti intermetallic alloy has been changed from the tetragonal D0(22) to the L1(2) cubic structure. The cast alloy shows considerable compression ductility at room temperature. To improve its mechanical properties further, hot-working experiments have been conducted. The results showed that the Al67Mn8Ti25 intermetallic alloy maintains very good hot-workability, the cast alloy can be reduced 60% by a single hot-pressing stroke without cracking. The role of hot-working on the microstructure and the mechanical properties of the alloy have been studied. It was found that the hot-worked alloy shows a deformed structure and some work-hardening after hot-working. Experiments indicated that the starting temperature for recrystallization is about 1173 K and complete recrystallization of the deformed alloy occurs at about 1273 K. Good hot-workability and a high recrystallization temperature permit potential for elevated temperature use. A transmission electron microscopy study on the evolution of dislocation structures in the recovery and recrystallization processes is also reported.