R. V. Minakova

Texture formation in the cold rolling of pseudo-alloys

The formation of metallographic and crystallographic textures and the properties of the composite materials W - Cu, W - Ni - Fe, and Ag - Ni with a metal matrix were studied after 5–85% squcezing by rolling. It was established that crystallographic texture tended to be suppressed by the localization of deformation and formation of cracks along interfaces, the type of which, as well as the character of the structure-sensitive properties depended on the nature of the material and its processing history.

Microstructural evolution of Cr–Cu composites in liquid-phase sintering

The paper examines the effect of temperature and volume fraction of refractory particles on the kinetics of their growth during liquid-phase sintering of Cr–Cu composites in the temperature range 1150–1350°C under a vacuum of (2–4)∙10–3 Pa. It is established that the growth kinetics of average-size particles is described by a near-cubic law and the decrease in their number is determined by a near-inverse dependence: the apparent activation energy (Q = 113 ± 10 kJ/mol) is of the order of magnitude comparable to that of diffusion in liquid metals. According to the Lifshitz–Slyozov–Wagner theory (LSW theory), diffusion coalescence is indicative of diffusion-controlled particle growth. Experimental growth constants are one order of magnitude higher than those calculated within the classical LSW theory. The increase in the growth rate constant with volume fraction of refractory particles varying from 0.4 to 0.7 and the change in the particle size distribution function after sintering for 90 min at 1200°C agree with the Ardell model, which modifies the LSW theory considering the effect of volume fraction of particles on their growth kinetics.

Current state and prospects of high-speed electron-beam evaporation and subsequent vacuum condensation of metals and nonmetals to produce electric contacts and electrodes

The paper describes the structural features and properties of condensed composites based on copper and refractory metals (W, Mo, Cr). These condensed materials have a lamellar structure with a hierarchy of macro-, micro-, and submicron levels. In the condensed materials based on copper and chromium, supersaturated chromium solid solutions form and decompose. Examples of applying the Cu–Mo, Cu–W, Cu–Cr, and Cr–Al2O1 composites condensed from the vapor phase to produce electric contacts and electrodes are shown.

Copper powder rolling technology (review)

Published data are analyzed for the rolling technology of copper powder. It is established that production parameters for manufacturing copper rolled product are predetermined by the preparation method, chemical composition, shape and size of the original powder, the type of rolling equipment, and also the intended use of the final product.

Contact interaction, structure, and properties of W(Mo, Cr)-Cu composites with additives

The results of research on the effect of additives on the adhesive characteristics and phase-boundary formation in W(Mo, Cr)-Cu systems are summarized. The distinctive features of structure formation and the properties of powder composites compacted in the presence of a liquid phase have been studied. Composites with optimal properties (high-temperature hardness, electrical conductivity, high adhesiveness, and stable structure) have been identified.

Structure formation and properties of molybdenum-base powder composites

The purpose of this work was to investigate physicochemical conditions of formation and features of structure formation of molybdenum-base composites and, in particular, to study the adhesion characteristics and features of contact interaction in Mo-Cu-Ni(Co) systems, to investigate the distribution of the basic elements and impurities, the phase composition, the structure, and certain properties of the materials and parts. A combination of methods was used including x-ray spectral microanalysis, Auger spectroscopy, x-ray diffraction phase and structure analysis, microhardness and hot hardness methods, scanning electron microscopy, and metallography by optical microscopy. The influence of hot hardness of the composite was selected as the criterion of evaluation and it was found that increases in hot hardness and in high-temperature oxidation increased the life and service properties of electrodes used for spot welding and brazing in production.