Brittle Fracture Surface Morphology
When a material fractures brittlely, a series of V shaped chevron markings can form along the material as the fracture energy progresses along, with the tips pointing back toward the crack initiation site.
Alternatively the fracture energy could spread out from the crack, forming lines and ridges that radiate out through the material.
Although, as most brittle materials are very hard and fine grained, it is possible for there to be no discernible cracking or patterns along the surface of the material, as despite the energy released, the material is resistant to plastic deformation. Which is what causes micro-voids to form in more elastic materials.
Due to the splitting of the crystals either through inter or trans granular fracturing the surface of fracture can be very smooth and shiny, especially when compared to ductile fracture.
Ductile Fracture Surface Morphology
When a ductile material fractures, it can do so in a few ways, which form different patterns along the fracture surface. Because the material is susceptible to plastic deformation, the dimples formed from fracturing voids, are well defined. Causing a rough fibrous texture to be formed along the surface in direct comparison to the smooth surface of brittle fracture.
Bellow are the three types of forces and the surface patterns they form:
Tension
Results in equiaxed (Spherical voids, which are a few micrometers in diameter) voids that coalesce in patterns which are in line to the loading axis.
Shear
Results in elongated voids that coalesce in the planes of shear stress. The void on both planes form a chevron (< shape) shape, which on one plane will point backward toward the point of fracture origin and on the other, away from it.
Tension and Bending
Results in elongated voids, but the directions of the chevrons on both planes are in the same direction.