Study of beryllium hardening obtained by powder metallurgy

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.

Model Analysis on Particles Size Distribution of Beryllium Powder

A physics model was established for describing the particle size distribution of beryllium (Be) powder produced by impact attrition milling. In this model, two factors were considered: the first, the distribution of existing state of particles with different original kinetic energy should obey the Maxwell-Boltzmann statistics after impacted, it was that, being at higher energy level made big particles unstable, which were easy to be fractured into smaller pieces in impact attrition process, this influencing factor described as the negative exponential of particles size; the second, the tendency to remain low surface energy needed particles should keep big volume as much as possible, this effect defined as the cube of particles size. The actual particle size distribution of Be powder was resulted from the competition between these two factors. Calculating result from the model was in good agreement with data from measurement.

Incorporation of a new design of backing seat and anvil in a Merrill–Bassett diamond anvil cell

A modification to the Merrill–Bassett miniature diamond anvil cell is reported here, with the inclusion of tungsten carbide backing seats with Boehler–Almax-cut diamonds to replace the previously used beryllium seats and (typically) modified brilliant-cut anvils. This has led to the removal of troublesome beryllium powder lines from diffraction images, while maintaining the pressure range and opening angle of the original design.