Formation mechanism of TiB2 nanoparticles and development of TiB2p/6201 nanocomposites as a neoteric conducting material

Abstract

TiB 2 nanoparticles were fabricated by the melt reaction between Al-10Ti and Al-3B master alloys. The reaction mechanism is ascribed to the decomposition of Al 3 Ti to release free Ti atoms, which diffuse across the AlB 2 /Al interface and substitute the Al atoms to form TiB 2 . This substitution produces a layer of pseudo-TiB 2 on the prism planes {10‐10} AlB2 firstly, which has the same lattice structure and the similar values of the lattice parameter as AlB 2 . It follows the fact that the nucleation occurs at the prism planes {10‐10}. Subsequently, the epitaxial transformation of TiB 2 particles is initiated inward the pseudo-TiB 2 , which becomes detached from the substrate owing to the crystallographic mismatch between the two, thus forming the TiB 2 nanoparticles. The exposed AlB 2 prism surfaces continue to react with Ti atoms until they are totally consumed. Increasing the reaction temperature, prolonging the holding time could improve the extent of reaction, thus increasing the electrical conductivity and reducing the elastic modulus. Especially, the effects of ultrasonic vibration treatment (UVT) on the reaction process were explored. Cavitation and acoustic flow generated by UVT showed a magnificent potential for promoting the reaction in melts. Thanks to the interface reaction, nano-TiB 2 particles can be generated. The nano-TiB 2p /6201 composites produced by this method recorded significant improvement in the tensile properties. • Nano-TiB 2 particles are generated on the prism planes of micron AlB 2 particulates. • Reaction mechanism of born treatment is revealed at the atomic scale. • The reaction is effectively accelerated by ultrasonic vibration treatment.