Crack propagation mechanism of titanium nano-bicrystal: a molecular dynamics study

The effects of temperature and twin grain boundary position on the crack propagation mechanism of pure $$\upalpha $$ α -Ti were studied by molecular dynamics simulation. Under room temperature, the twin grain boundary in the intergranular crack model can guide the crack propagation path and the formation of voids intensifies the crack propagation. With the increase of temperature, the brittle–ductile transition of $$\upalpha $$ α -Ti occurs and the dominant factor of plastic deformation changes from grain boundary to dislocation. When the twin grain boundary is rotated $$90^{\circ }$$ 90 ∘ , the stress–strain curve shows that the elastic modulus and yield strength of the transgranular crack model are better than the intergranular crack model at room temperature. During the tensile process of the transgranular model, the twin boundary improves the strength by hindering the dislocation movement. A new dislocation source is formed at both ends of the grain boundary after fracture, which improves the plasticity. Graphic abstract