Creep and fatigue are the most prevalent causes of rupture insuperalloys, which are important materials for industrial usage,e.g. in engines and turbine blades in aerospace or in energyproducing industries. As temperature increases, atom mobilitybecomes appreciable, affecting a number of metal and alloyproperties. It is thus vital to find new characterization methodsthat allow an understanding of the fundamental physics of creep inthese materials as well as in pure metals. Here, the author shows how new in situ X-ray investigations andtransmission electron microscope studies lead to novel explanationsof high-temperature deformation and creep in pure metals, solidsolutions and superalloys. This unique approach is the first tofind unequivocal and quantitative expressions for the macroscopicdeformation rate by means of three groups of parameters:substructural characteristics, physical material constants andexternal conditions. Creep strength of the studied up-to-date single crystal superalloysis greatly increased over conventional polycrystalline superalloys. From the contents: - Macroscopic characteristics of strain at high temperatures - Experimental equipment and technique of in situ X-rayinvestigations - Experimental data and structural parameters in deformedmetals - Subboundaries as dislocation sources and obstacles - The physical mechanism of creep and the quantitative structuralmodel - Simulation of the parameters evolution - System of differential equations - High-temperature deformation of industrial superalloys - Single crystals of superalloys - Effect of composition, orientation and temperature onproperties - Creep of some refractory metals For materials scientists, solid state physicists, solid statechemists, researchers and practitioners from industry sectorsincluding metallurgical, mechanical, chemical and structuralengineers.