The consequences of something breaking can be a pest, or utterly disastrous, as when the pedal drops off one’s bike, but without it, biting and crunching, breaking into crisp packets, pulverizing coal, oil drilling and many other processes would be impossible. The most dramatic failures are catastrophic, but sometimes they can be very gradual even in the most brittle materials. This TLP discusses what determines when a material will break, and whether failure will be catastrophic or more gradual. The emphasis here is on brittle fracture, and although all of this is relevant to metals, the details of ductile fracture are not discussed.

On completion of this tutorial you should understand:
• that materials break by cracking;
• what determines whether a material will crack or not;
• what determines whether cracking is catastrophic or more gradual;
• the concepts of the fracture energy, strain energy release rate, fracture toughness and stress intensity factor.

Questions and links to further reading are also included.

[Description and screenshot taken from the DoITPoMS page for this TLP. (c) University of Cambridge used under the terms of their CC BY-NC-SA 2.0 license.]

Before you start it will be helpful to have an understanding of solute partitioning and the formation of dendrites. The TLP on Solidification of Alloys covers these topics.

On completion of this tutorial you should:
• Understand the meaning of the Biot number, how it affects the temperature profile in a casting, and the resulting microstructure.
• Be able to explain the formation of the microstructure observed in a cast ingot.

• Be familiar with some common methods of casting, their advantages and disadvantages, and be able to choose a suitable process for manufacturing a variety of metallic components.

Questions and links to further reading and websites are also included.

Description and screenshot taken from the DoITPoMS page for this TLP. (c) University of Cambridge used under the terms of their CC BY-NC-SA 2.0 license.]