[PO-E1] Poster Session 1

[P1-29] The influence of nano-sized Ti₃Al particles on the mechanical properties of α-titanium alloys

^○Yan He^1,2,3, Wang Hao¹, Dongsheng Xu¹, Yang Rui¹ (1.IMR, CAS, China, 2.Coll. of Physics Science and Technology, SYNU, China, 3.Univ. of chinese Academy of Sciences, China)

In α-titanium alloys, Ti₃Al (α₂ phase) precipitates under a perceivable aluminum content. The size and distribution of α₂ particles has significant influence on the mechanical property of α-Ti alloys. Experimentally, it is found that nanometric α₂ particles drastically decrease the toughness of α-Ti alloys after certain thermal treatment. However, the strength and the ductility do not vary linearly with the size of α₂ particles and the atomic details of hardening and fracture remain unclarified. Therefore, we employed molecular dynamic simulation with the embedded-atom potential to systematically study the deformation process of α-Ti with different size and distribution of α₂ particles. The result shows that 1) the α/α₂ interface is coherent; 2) in an α grain with an α₂ particle and incoming dislocations, the existence of an α₂ particle blocks the dislocations and the strength increases with the size of the α₂ particle; and subsequently cracks nucleate at the impacting site on the gain boundary with the crack stress decreasing with the size of the α₂ particle; 3) the resulting strength and toughness vary with the size of the α₂ particle in a parabola manner. The present simulation result quantitatively agrees with experiments and helps identifying the critical α₂ particle size for the design of structural titanium alloys.