Shock-Wave Consolidation of Boron and Carbon Containing Ultrafine Powders and Investigation Their Structure/Properties

The unique properties of the ultrafine grained composites, makes them attractive for aerospace, power engineering, machine and chemical and other practical applications. Carbon and Boron based composites are important and on high demand because of their specific properties and wide areas of application. It must be noted that SiC, TiC, TiB2 and B4C are characterized with high hardness, wear resistance, corrosion resistance, they have high melting temperatures. Therefore they find wide application for preparing the details to working at high temperatures and aggressive media. According to the phase diagrams in the selected systems, the composites/intermetallics may be obtained with wide spectrum of phase composition, in crystalline and amorphous structures. Depending on the composition and structure, the synthesized composites exhibit different specific properties. The potential of the system for development of new structural/composite materials in different thermodynamic conditions is very attractive. Nano structured composite materials of Ti-Al-Si-B-C system, prepared in the form of micromechanical blends, solid solutions and intermetallic compounds are of great practical interest because of improved mechanical properties in comparison with coarse grain material (>1 μm). The methodology and technology for the fabrication of bulk materials from ultrafine powders of Ti-Al-B-C and Si-B-C systems are described in the paper. The crystalline coarse Ti, Al, Si, C powders and amorphous B were used as precursors, and blends with different compositions of Si-C-B, Ti-Al-B-C and Ti-Al-C were prepared. The powders were mixed according the selected ratios of components to produce the blend. For Mechanical alloying (MA) the high energetic "Fritsch" Planetary premium line ball mill was used. Ratio ball to powder by mass was 10:1. The time of the processing was varied from 2 to 5 hours with rotation speed of 500 rpm. For the consolidation and bulk sample formation Explosive Compaction (EC) technology was used. The experiments were performed at room temperature. The shock wave pressure was varied in the range of 5-20 GPa. The ultrafine powders and bulk compacts of different compositions were prepared for investigations. The microstructure was studied by SEM and the effective regimes for obtaining nanopowders and nanocomposites in Ti-Al-Si-B-C composition has been established.