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

• Liquid Ti-12Al-8V alloy was undercooled by 212 K with electromagnetic levitation.
• The maximum growth velocity of β dendrites attained 14.9 m/s at 212 K undercooling.
• β→α phase transformation can be suppressed at high cooling rates above 3×103 K/s.

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 β phase and led to an actual maximum undercooling of 212 K (0.11TL). The primary β 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 3.31×103 K/s, the primary β phase was retained metastably to ambient temperature.