HIGH-TEMPERATURE OXIDATION OF MATERIALS

The high-temperature oxidation of a wide variety of materials has been investigated, viz: group I-VIII metals and their alloys, refractory c ompounds involving carbides, nitrides, borides, and silicides of the g roup IV-VI transition metals, and materials based on them, and composi te materials for various applications. The basic laws and mechanisms o f interaction of these materials with gaseous media have been determin ed. Heat resistance vs composition relationships for various types of binary systems have been defined, based on studies carried out over a broad range of temperatures (500-1600 degrees C), concentrations of se cond component (0-100%), and an oxidation rime of IO hours. The redist ribution of alloying elements during oxidation has been studied, and i ts effect on oxygen solubility, heat resistance, phase composition and morphology of the scale, and structure of the scale-alloy interface c larified. The definitive role of metal-ion diffusion in the oxidation behavior of titanium and zirconium, and the catastrophic oxidation of zirconium and its alloys, has been demonstrated. Alloying group IV met als with elements of higher valency produces a reduction in oxygen sol ubility due to the increase in electron concentration, and a reduction in the extent of scaling. The relationship of the heat resistance vs composition diagrams to the phase diagrams of the binary systems has b een elucidated.