STRUCTURE AND MECHANICAL PROPERTIES OF THICK METAL CONDENSATES STRENGTHENED WITH VARIOUS DISPERSED PARTICLES
I. STRUCTURE AND YIELD STRENGTH OF DISPERSION-STRENGTHENED THICK METAL CONDENSATE

Abstract

The paper presents the study results on the structure and yield strengths of 0.8–2.0 mm thick dispersion-strengthened condensates produced by an electron beam evaporation with subsequent deposition of vapor phase onto metal substrates. Pure metals of Fe, Ni, Cu, W, and the ZrO₂, Al₂O₃, NbC, TiC, TiB₂, ZrB₂ refractory compounds were used as metal matrices and strengthening phases, correspondingly. The two-phase condensates in a form of 120 mm × 200 mm × (0.8–2.0) mm plates with variable content of dispersed particles along the length of specimens were produced by simultaneous evaporation of the chosen metal and refractory compound from two independent water-cooled copper crucibles. The process is followed by condensation of vapor mixture onto planar steel and niobium substrates. The Fe, Ni, Cu, W ingots with a diameter of 69 mm and length of 160–200 mm served as initial metal materials. The ingots were produced by an electron beam remelting of Armco iron, NP-0 nickel, M0 copper and compacted powder tungsten rods, respectively, as well as sintered pressed rods of commercially pure refractory compounds (ZrO₂ + 5% CaO), Al₂O₃, NbC, TiC, TiB₂, ZrB₂ with a diameter of 48 mm and 60 mm long. The temperature of substrates was 600 °C for iron, 650, 850, 1100 ºC for nickel, 750 ºC for copper (steel substrates), and 1200, 1400, 1600 ºC for tungsten (niobium substrates). Such temperatures were maintained through continuous electron beam heating of metals in scanning mode. The choice of substrate temperatures was determined by the necessity to obtain optimal mechanical properties and structure of metallic matrices. Vacuum value amounted to (1,33 · 10^–2)–(6,66 · 10^–3) Pa. A thin sublayer of stabilized dioxide zirconium was predeposited onto the substrates to separate condensates from them. The refractory compounds have different physicochemical properties and interact with the metal matrices in different ways. The insertion of various types and amounts of dispersed particles into metal matrices has a major influence on the refining of the structure of dispersed reinforced condensates. It was shown that the strength of studied composites depends on a volume content of the strengthening phase, particle size, and a dislocation structure developed during plastic deformation. The dispersoid type affects the rate of the dislocation structure formation in two-phase composites considering the wettability degree of the strengthening particles with matrix metal.