Brittle, Brittle Fracture
Index
A brittle material is one that fails in the elastic region during deformation. Brittle fracture tends to generate two new surfaces that are normal to the tensile axis of the sample. 

For a polycrystalline material, brittle fracture may cause failure along the grain boundaries (inter-granular fracture) or through the grains (trans-granular fracture). The mean surface tends to be normal to the tensile axis in both cases. The photograph shows brittle fracture in a low carbon steel.

From: Schaffer et al, "The Science and Design of Engineering Materials," 
Irwin (1995)