The 9th International Conference on Multiscale Materials Modeling

Presentation information

Symposium

E. Deformation and Fracture Mechanism of Materials

[SY-E10] Symposium E-10

Thu. Nov 1, 2018 11:15 AM - 12:30 PM Room2

Chairs: Irene Beyerlein(University of California at Santa Barbara, USA), Dongsheng Xu(Institute of Metal Research, CAS, China)

[SY-E10] Atomic structure of gamma/alpha2 interface and its influence on plastic deformation of lamellar TiAl alloys

Hao Wang1, Aidong Tu1, Yanxia Liu2, Dongsheng Xu1, Rui Yang1 (1.Institute of Metal Research, CAS, China, 2.Dept. of Physics, Liaoning University, China)

TiAl alloys with the γ-TiAl/α2-Ti3Al lamellar structure exhibit excellent high temperature performance. However, the strong anisotropy of the lamellae leads to the strong dependence of mechanical properties, in particular the fatigue behavior, on lamella orientation, thickness, volume fraction, etc. In the present work, molecular dynamics with the embedded-atom potential is employed to investigate the energy of both the coherent and incoherent γ/α2 interfaces. The interface coherency is found to depend on the volume ratio of the γ lamellae over the α2lamellae, resulting in a critical volume ratio, below/above which the interface is coherent/incoherent. Loading perpendicular and parallel to the lamella interface indicates that the yield strength of coherent interface is higher than that of the incoherent interface. Plastic deformation mostly occurs first in the γ region and transmits to the α2 region via dislocations or twinning across the γ/α2 interface. Subsequent fracture behavior also depends on the γ/α2 volume ratio. With the coherency and incoherency interfaces, crack nucleates within the γ region and at the γ/α2 interface, respectively. The present result thus contribute to the evaluation of the structural stability and the improvement of mechanical performance of TiAl alloys.