EFFECTS OF ADDITIONAL ELEMENTS ON MICROSTRUCTURE AND PRECIPITATION BEHAVIOR IN RAPIDLY SOLIDIFIED AL-TI BASE ALLOYS

Rapidly solidified Al-Tb base alloys were prepared by melt spinning at the cooling rate about 10(7) K/s. The melt-spun ribbons were used to observe the microstructures after heat treatment. In the supersaturate d Al-Ti-Si alloy, age hardening occurred after 1 h anneal in the tempe rature range of 400 similar to 500 degrees C, which seems to be attrib uted to the precipitation of metastable L1(2)-(Al,Si)(3)Ti phase. Howe ver, the microhardness was relatively low because of the low v/o and t he insufficient stability of precipitates. Thus, Cr was added to Al-Ti -Si alloys in order to stabilize the microstructures and to increase t he v/o of precipitates. As a result, the alloys containing Cr were eva luated to possess the improved properties at the service temperature.