Synthesis of Nano Composites from Ti-Al-B-C powders by Adiabatic Explosive Compaction

Recent developments in materials science have increased the interest towards the bulk nano materials and the technologies for their production. The unique properties which are typical for the composites fabricated in Ti-Al-B-C... [ view full abstract ]

Recent developments in materials science have increased the interest towards the bulk nano materials and the technologies for their production. The unique properties which are typical for the composites fabricated in Ti-Al-B-C systems makes them very attractive for aerospace, power engineering, machine and chemical applications. In addition, aluminum matrix composites (AMCs) have great potential as structural materials due to their excellent physical, mechanical and tribological properties. Because of good combinations of thermal conductivity and dimensional stability AMCs are found to be also potential materials for electronic application. The methodology and technology for the fabrication of bulk materials from ultrafine grained powders of Ti-Al-B-C system are described in this paper. It includes results of theoretical and experimental investigation for selection of powder compositions and determination of thermodynamic conditions for blend preparation, as well as optimal technological parameters for mechanical alloying and adiabatic compaction. The crystalline coarse Ti, Al, C powders and amorphous B were used as precursors, and blends with different compositions of Ti-Al, Ti-Al-C, Ti-B-C and Ti-Al-B were prepared. Preliminary determinations/selections of blend compositions were made on the basis of phase diagrams. The powders were mixed according the selected ratios of components to produce the blend. Blends were then processed in high energetic planetary ball mills for mechanical alloying, syntheses of new phases, amorphization and production of nano and ultrafine powders. The blends processing time ranged from 1 to 24 hours. The optimal technological regimes of nano blend preparation were determined experimentally. The ball milled nano blends were placed in metallic tubes and loaded by explosive energy for further consolidation and synthesis in adiabatic regime. The effect of the processing parameters on the structure and properties of the nano and ultrafine materials was investigated and is discussed here. For consolidation of the mixtures the explosive compaction technology was applied at room temperatures. The relationship of the ball milling technological parameters and the consolidation conditions on the structure/properties of these materials is presented and discussed in this paper.