Synthesis and Investigation of Properties of Beryllium Ceramics Modified with Titanium Dioxide Nanoparticles.

Samples of beryllium ceramics, with the addition of micro- and nanoparticles TiO2, have been obtained by the method of thermoplastic slip casting. The microstructure of batch ceramics, consisting of micropowders and ceramics with TiO2 nanoparticles sintered at an elevated temperature, has been investigated. It was found that the introduction of TiO2 nanoparticles leads to changes in the mechanisms of mass transfer and microstructure formation, and the mobility of TiO2 at interfacial grain boundaries increases, which leads to the formation of elements of a zonal shell structure. The reduction of intergranular boundaries leads to an increase in density, hardness, and mechanical strength of ceramics. The whole complex of properties of the synthesized material, with the addition of TiO2 nanoparticles in the amount of 1.0-1.5 wt.%, leads to an increase in the ability to absorb electromagnetic radiation in the frequency range of electric current 8.2-12.4 GHz. The analysis and updating of knowledge on synthesis, and the investigation of properties of beryllium ceramics modified by nanoparticles, seems to be significant. The obtained results can be used in the creation of absorbers of scattered microwave radiation based on (BeO + TiO2) ceramics.

Effect of the Dislocation Substructure Parameters of Hadfield Steel on Its Strain Hardening.

This article presents a study of changes in the microstructure of Hadfield steel depending on the tensile deformation and cold rolling with the strain/stress level. It has been established that the change in the "σ-ε" curve (at ε = 5%) is accompanied by a 1.5-times decrease in the strain-hardening coefficient. At ε = 0 to 5%, the structure contains dislocation loops, the interweaving of elongated dislocations, single-layer stacking faults. At ε = 5%, the structure contains multilayer stacking faults and mechanical microtwins. At ε > 5%, there is an intense microtwinning with no long dislocations and stacking faults. The most intense twinning develops in the range of deformation degrees of 5-20%, while the number of twins in the pack increases from 3-4 at ε = 10% to 6-8 at ε = 20%. When mechanical twinning is included, a cellular dislocation substructure begins to develop intensively. The cell size decreases from 700 nm at ε = 5% to 150 nm at ε = 40%. Twinning develops predominantly in systems with the largest Schmid factor and facilitates the dislocation glide. The results may be of interest to the researchers of the deformation processes of austenitic alloys.