• Question: Does each material get damaged in different ways because of their different properties?

    Asked by caitlhan to James on 13 Jun 2011.
    • Photo: James Marrow

      James Marrow answered on 13 Jun 2011:

      Yes – to understand how materials get damaged, you need to understand how they deform and absorb energy.

      Metals, for instance, deform by sliding of atomic planes over each other. This absorbs energy and is also the mechanism that toughens metals and makes them ductile. We strengthen metals by making this sliding more difficult, although this also usually makes them more brittle. Ceramics cannot deform by this mechanism as the atomic bonds are too strong, so they crack very easily. We can make ceramics stronger by distributing this damage in a cloud of very small cracks, rather than allowing a single large crack to develop.

      To do this needs careful control of the way that materials are processed, and sophisticated microscopes to study the mechanisms of deformation and damage