The revised chapters are precisely the thermodynamic and metallurgical foundations that govern the design of high entropy alloys, introduce in their different applications in the fields of energy, aerospace, metal shaping, and advanced manufacturing, predictive thermodynamics, microstructural analysis and their importance in the mechanical behavior and formation of strengthening mechanisms, to end with the analysis of the whole document in the application of the mechanical response of high entropy alloys in condition of high temperatures and cryogenic temperatures in addition to dynamic loads such as fatigue and reflecting the importance of the manufacturing process and the microstructure has in the performance at working conditions, leaving in evidence the dependence of the microstructure and its defects as well as its present phases allow to obtain a good behavior at macroscopic level. For this reason, the analysis of the evaluation of mechanical behavior was also linked through multiscale analysis through different applied methodologies and how they are combined in a way coupled to the time and space access system.