Primary phase growth and microstructure evolution of rapidly solidifying ternary Ti-12Al-8V alloy

Liquid Ti-12Al-8V alloy was rapidly solidified by electromagnetic levitation and drop tube techniques. The levitation processing avoided the violent heterogeneous nucleation of primary beta phase and led to an actual maximum undercooling of 212 K (0.11T(L)). The primary beta dendrites exhibited a high growth velocity up to 14.9 m/s but subsequently transformed into basket weave structures. Drop tube experiments indicated that the final microstructure morphology was determined by the coupled influences of undercooling extent and cooling rate. If the cooling rate exceeded 3.31 x 10(3) K/s, the primary beta phase was retained metastably to ambient temperature. (C) 2016 Elsevier B.V. All rights reserved.