Study of beryllium hardening obtained by powder metallurgy

Abstract

In the first part of the article the results of the study of powder hardening processes occurring during beryl powders consolidation by the hot pressing method are shown. The dependences of the content and morphology of the hardening phase depending on the content of low-melting impurities on the sintered Beryllium powder grains surface have been studied. A hypothesis is proposed that explains the transition of an oxide film from an amorphous to a crystalline state – devitrification, and the effect of low-melting impurities on the mechanism of the devitrification process and, as a consequence, on the effect of "dispersion-grain boundary" hardening. This hypothesis is based on theoretical confirmation with the provision of graphic material demonstrating the process of devitrification, accompanied by a dispersed-grain-boundary hardening mechanism. The final results of statistical processing carried out on industrial batches showing the dependence of the impurities content influence on the properties of hot-pressed beryllium are presented. In the second part of the article the results of studying the effect of hardening of beryllium obtained in the process of sintering by the method of hot isostatic pressing (HIP) are shown depending on the temperature of powders consolidation. Based on the results of electron microscopic studies, the dynamics of the reinforcing phase formation at the grain boundaries of sintered beryllium is shown. The quantitative dependence of the precision elastic limit and the conditional yield stress of gas-statically compressed beryllium on the size of the strengthening beryllium oxide particles and the consolidation temperature of the powders have been established. The resulting equation gives a description of the "dispersed-grain-boundary" hardening mechanism of isostatically pressed beryllium. All dependencies are also represented by graphic material reflecting the essence of the research.