5.5 Summary of Section 5
The phase of a material is characterised by its physical state (e.g. solid, liquid or gas), a distinctive arrangement of the atoms, and its chemical composition.
Material properties can change suddenly as the temperature increases or decreases, corresponding to changes of phase and the degree of order associated with the arrangement of atoms.
Shape memory alloys are examples of a wide range of useful engineering materials that exploit critical phenomena arising from phase changes.