Brittleness

Conversely, with fewer slip systems, less plastic deformation can occur, and the metal will be more brittle.

For example, HCP (hexagonal close packed) metals have few active slip systems, and are typically brittle.

Brittle polymers can be toughened by using metal particles to initiate crazes when a sample is stressed, a good example being high-impact polystyrene or HIPS.

The least brittle structural ceramics are silicon carbide (mainly by virtue of its high strength) and transformation-toughened zirconia.

A different philosophy is used in composite materials, where brittle glass fibers, for example, are embedded in a ductile matrix such as polyester resin.

This happens as an example in the brittle–ductile transition zone at an approximate depth of 10 kilometres (6.2 mi) in the Earth's crust, at which rock becomes less likely to fracture, and more likely to deform ductilely (see rheid).

Supersonic fracture is crack motion faster than the speed of sound in a brittle material.

This phenomenon was first discovered[citation needed] by scientists from the Max Planck Institute for Metals Research in Stuttgart (Markus J. Buehler and Huajian Gao) and IBM Almaden Research Center in San Jose, California (Farid F. Abraham).