The evolutuion of a body can be studied using the equations of conservation of mass, of energy and the Virtual Power Principle. For a complete modelling it is also necessary to give additional informations that characterize the behaviour of a paticular material. This is done by means of constitutive hypothesis. A solution of these equation Will be mechanically admissible if it does not violate the Second Law of Thermodynamics. This work presents a systematic procedure to obtain constitutive equations that satisfy automatically a local version of the Second Law of Thermodynamics. The Theory developed here generalizes the classical ideas of the Thermodynamic of Irreversible Process: The uncoupling between the thermic and the intrinsic dissipation is not used as a basic assumption and the existence of a non convex and non differentiable potencial of dissipation is admissible. Using this basic thermodynamocal theory, the following topics were developed: - Classification and analysis of the usual behaviour of solids at infinitesimal deformation (elasticity, elastoviscoplasticity). - Modelling, numerical simulation and experimental evaluation of the coupling between aging and plasticity in metals and alloys (hardening due to precipiation process-change of phase). At the end this work, it is also presented na alternative of extension of the study made for solids to a finite deformation context, with the purpose of the simulation of metal forming processess.