Plasma methods of obtainment of multifunctional composite materials, dispersion-hardened by nanoparticles

Abstract

Abstract.The new approach in developed plasma methods consists in that dispersionhardening additives (TiC, TiB 2 in particular) are not mechanically added to powder mixture as additional component, as in conventional methods, but are instead synthesized during high voltage electric discharges (HVED) in disperse system "hydrocarbon liquid -powder"; preservation of ultrafine structure is ensured due to use of spark plasma sintering (SPS) as a consolidation method. HVED in disperse system "hydrocarbon liquid -powder" due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro-(from 10 -6 to 10 -7 m) and nanosized (from 10 -7 to 10 -9 m) composite powders of hardening phases. SPS is the passage of pulsed current (superposition of direct and alternating current) through powder with the simultaneous mechanical compressing. The formation of plasma is initiated in gaseous phase that fills gaps between particles. SPS allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro-and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10 -20 %), hardness and wear-resistance (by 30 -60 %) of obtained materials. IntroductionNuclear energetics is one of the most dynamic sectors of the world economy. Each new generation of nuclear plants becomes more efficient and safe, but demands the use of materials that have high strength, wear-resistance and are capable of working in aggressive environments. Thus, development of construction materials for nuclear plants is important scientific and technical task.Creation of heterogeneous structure in material, which is a plastic matrix with hard inclusions, is a necessary condition to ensure materials strength and wear-resistance. Heterogeneous materials include metal-matrix composites of Fe -Ti -C system, obtained with methods of powder metallurgy. These materials have high strength, hardness, their wear resistance is close to tungsten-containing alloys and their modification by boron carbide leads to increase in corrosion and radiation resistance [1].