Polymorphism Phase:

Polymorphism is the property or ability of a metal to exist in two or more crystalline forms depending upon temperature and composition. Several metals and metal alloys exhibit this property. Uranium is an excellent instance of a metal which exhibits polymorphism. Uranium metal could exist in three different crystalline structures. Every structure exists at a specific phase, as described within Figure.

Figure: Cooling Curve for Unalloyed Uranium

1. The alpha phase, from room temperature to 663ºC

2. The beta phase, from 663ºC to 764ºC

3. The gamma phase, from 764ºC to its melting point of 1133ºC