Examination of crack path in silicon multi-crystals.

Dynamic fracture of silicon multi-crystal merits a systematic investigation given the complexity induced by microstructure defects, in particular grain boundaries. How crack selects its path in the presence of substantial grain boundaries is an issue still under debate in literature. In this work, fracture behavior of multi-crystalline silicon is carefully examined through bending tests, bringing to light new crack propagation scenarios. In the case of multi-cracking, massive branching events emerge, and crack paths are heavily affected by burst waves. When a single crack propagates across grain boundaries, orientation mismatch between cleavage planes generates an important constraint effect, leading the crack to eventually propagate along (112) plane, i.e., a path scarcely seen in single crystal. Perfect crack propagation along coherent Σ 3 twin boundary can hardly be achieved, presumably due to the crack inertia effect. Moreover, crack is found to incessantly deviate at the two sides of high order grain boundaries, resulting in a zigzag crack path. The observations suggest that grain boundaries are not prone to break up but significantly affect crack path in silicon multi-crystals. • Cascading waves and branching break up the monopoly of (111) cleavage in silicon. • Fracture along coherent TB cannot be achieved presumably due to crack inertia effect. • Misorientation plays a vital role in fracture path selection upon crossing GB. • High order GB is revealed to be unfavorable crack path in silicon multicrystal. [ABSTRACT FROM AUTHOR]