Tensile deformation and fracture behaviors of high purity polycrystalline zinc

The damage and fracture behaviors of high purity polycrystalline zinc with two grain sizes during tension were investigated experimentally at different strain rates. It was found that specimens with coarse grains (∼1 mm) showed serrated flow behavior and failed in intermittent brittle cleavage fracture, while specimens with fine grains (∼70 μm) showed no cleavage crack initiation before necking even at high strain rate. It was observed that the fracture process of the fine-grained specimen was highly related to strain rates. With the strain rate increasing, the damage mechanism transformed from formation of tearing cracks along interfaces (including grain boundaries, twin boundaries and kink band boundaries) and cavity coalescence into abrupt quasi-cleavage fracture. Based on the observation, the inter-crystalline fracture of zinc was investigated, and the damage and fracture behaviors of polycrystalline zinc during tension at room temperature were discussed in general.