Connecting Solidified Microstructure with Compression Properties for Bulk Ti–Al Alloys with V Addition Conducted by Electromagnetic Levitation and First Principle

Bulk Ti–Al based alloys with an approximate mass of 30 g are first prepared by electromagnetic levitation. The microstructures and the compression properties of Ti-45%Al-z%V alloys (z = 4, 8, and 12, atomic percent) at room and high temperatures are studied by experiments. The relationship between V content and the mechanical properties of γ and α₂ intermetallics has been investigated by first-principle calculations. It is clarified that V addition controls the phase contents and the microstructure characteristics. With the increase of V content, the microstructures of Ti-45%Al-4%V and Ti-45%Al-12%V are dominated by the phase transformations of α → γ and α → α₂, respectively. Ti-45%Al-4%V alloy is mainly constituted of fine full lamellar γ phase while Ti-45%Al-12%V alloy is composed of coarsening lath α₂ phase. Besides, the Young's modulus of Ti-45%Al-12%V alloy is smaller than that of Ti-45%Al-4%V alloy at 300 K, but the yield stress and ultimate compression stress are larger than that of Ti-45%Al-4%V alloy. The differences are attributed to the change of the main phase from γ to α₂ and the mechanical properties of crystals changed by V addition. In addition, V addition changes the Young's modulus of α₂ crystal from isotropy to anisotropy.