Phase transformations of materials is a common phenomenon. We are familiar with the melting of ice to wate, and boiling of water to steam, These transformations have been use to generate energy and propel machines. Steam has been used to produce electricity, and was one of the prime movers for the Industrial Revolution.
Phase tranformations can also be used to store energy, and many substances are applied in solar energy technology. Another common application is in the Rechargeable battery Industry. Important uses have been in alloy and steel making, and more generally, in composites .
There are many more applications.