Since the beginning of this subject we have been observing that a fundamental concept of materials science is that its properties are a direct consequence of their structure and microscopic atomic scale. In previous issues we have described and analyzed both the structure on different levels and different material properties. To fully appreciate the nature of the properties of microstructure-sensitive materials, this work will begin analyzing the phase diagrams, maps that guide us in the evolution of the microstructure. Phase diagrams are diagrams of balance, to complete the study of the microstructure we studied the heat treatment of materials, which will raise the temperature evolution versus time to obtain a desired microstructure. This topic will be kinetic studies, where we see the transformations of time-dependent phase.