Effect of growth rate on microstructure and tensile properties of Ti–45Al–2Cr–2Nb prepared by electromagnetic cold crucible directional solidification

Ti–45Al–2Cr–2Nb alloy was directionally solidified at different growth rates varying from 0.2 to 1.2mm/min by applying an electromagnetic cold crucible directional solidification technique. It was determined that well-aligned α2 (Ti3Al)/γ(TiAl) lamellar structures, B2 phase and blocky γ phase were generated in columnar grains. The interlamellar spacing (λ) decreases with the increasing growth rate (V) according to the relationship λ∝V−0.48, but the volume fraction of B2 is increased as growth rate is increasing. Results of uniaxial tensile tests show that the B2 phase and the blocky γ phase have significant influence on tensile failure when they are presented in the matrix of α2/γ lamellar structures, because they are usually employed to act as cracking sources during the tension process. [Display omitted] •Lamellae are finer and more uniform with the increase of the growth rate.•Volume fraction of the B2 phase decreases with decreasing growth rate.•Tensile properties are improved with decreasing B2 phase.