Jie Chen¹, Eric N Hahn², Avinash M Dongare¹, Saryu J Fensin²; ¹University of Connecticut, ²Los Alamos National Laboratory

Understanding how grain boundaries (GB) affects the deformation and spall behavior is critical to engineering materials with tailored fracture resistance under dynamic loading conditions. This understanding is hampered by a lack of a systematic data set, especially for BCC metals. To fill in this gap, molecular dynamics (MD) simulations are performed on a set of 74 Ta bi-crystals along [110] tilt axis to investigate the role of GB structure and properties (GB misorientation angle, energy, excess volume, etc.) on the deformation mechanism and the resultant spall strength. The spall strength is found to correlate directly with the capability of the GB to plastically deform by emitting dislocations and twinning. As the misorientation angle increases, a transition of dislocation-meditated to twinning-dominated plasticity is observed. Moreover, the local structure of the GB significantly affects the deformation behavior of Ta bi-crystals, resulting in significantly different spall strengths at the same misorientation angle.