[SY-I12] Symposium I-12

[SY-I12] Properties of β/ω phase interfaces in Ti and their implications on mechanical properties and ω morphology

^○Shuo Cao¹, Qing-Miao Hu¹, Rui Yang¹, Yong Jiang² (1.Institute of Metal Research, Chinese Academy of Science , China, 2.Central South University, China)

The ω phase strengthens β-Ti alloys effectively as a precipitate phase but decreases the plasticity with increasing size dramatically. To understand the strengthening and embrittlement mechanism of ω phase in the β-Ti alloys, the property of the β/ω interface is demanded. In this regard, we calculated the interface energies (γ_int ), cleavage energies (γ_cl ), and generalized stacking faults energy surfaces of the β/ω interfaces with different orientations using a first-principles method based on density functional theory. The results indicate that the strong anisotropy of the interface energy explains the ellipsoid morphology of the ω phase with its major axis parallel to the <111>_β direction. The calculated cleavage energies and unstable stacking fault energies γ_us are determined. By comparing the γ_cl/γ_us ratio of both interfaces and those of the bulk ω and β phases, we conclude that the interfaces are prone to crack initiation than the bulk and contribute to the ω-embrittlement of the β-Ti alloy.