Rapid solidification of Ti-Al alloys under electromagnetic levitation condition

Ti-Al alloys are usually difficult to undercool because of their high reactivity in the liquid state. In this paper, the maximum undercoolings of 328 (0. 17T_L) and 383K (0. 22T_L) were achieved respectively for liquid Ti-20at%Al and Ti-51at<A alloys under electromagnetic levitation condition. On the basis of high undercooling, we investigated the containerless rapid solidification of Ti-Al alloys. For Ti-20at%Al alloy, the XRD analysis indicated that the solidification microstructure consists of the two phases α-Ti and α₂-Ti₃Al. The solidification microstructure for Ti 51at<Al alloy involves two phases γ-TiAl and α₂-Ti₃Al. Meanwhile, the microstructure formation mechanisms of Ti-20at%Al and Ti-51at<Al alloys studied. With the increase of undercooling, the soMAed microstructure of Ti-20at<Al alloy significantly changes from dispersive distribution to lamellar structure, and that of Ti-51atAl alloy changes from coarse grain and lamellar structure to lamellar structure. Furthermore, the micro hardness of Ti-20at%Al and Ti-51at%Al alloys reaches the maximum value up to 557 and 712HV respectively at the undercooling of 260 and 246K.