—This critical review considers the fundamental concept, methods of obtaining, stability, and properties of a new class of materials—high-entropy alloys and compounds. An analysis of factors that determine the structure and stability of multicomponent disordered solid solutions has been carried out. Particular attention has been given to results obtained since 2017. The concept of temperature regions within stable and metastable phases, which explains the available experimental data, has been proposed.

This paper presents an analytical review of modern quasihomogeneous and discrete models of gasless combustion. Particular attention is given to experiments that make it possible to distinguish between homogeneous and microheterogeneous regimes of this process. It is shown that in the cases where different theoretical models predict different behavior of the combustion wave at the macroscopic or microscopic level, experiments provide data in support of discrete models. The development of these models allows for a fresh look at the problem of controlling the propagation parameters of gasless combustion waves and the development of reaction compositions with specified strictly reproducible characteristics.