PREPARATION AND THERMAL-STABILITY OF SUPERSATURATED NANOCRYSTALLINE AL-TI ALLOYS

Supersaturated nanocrystalline Al100-xTix alloys were mechanically alloyed in a planetary ball mill. For alloys with x = 5 and 10, a mixture of supersaturated solid solution Al(Ti) and an fee phase coexist while a single supersaturated solid solution Al(Ti) was obtained during mechanical alloying for x = 15 and 35. With increasing Ti content, from 5 to 35 at%, the grain size of the Al(Ti) solid solution decreased from 40 to 10 nm. The results suggest that fast diffusion along nanocrystalline grain boundaries is the main alloying process. DSC curves and TEM observations indicate that solute atom segregation can thermally stabilize the nanocrystalline solid solutions.