Study on the reaction mechanism and intermetallic compound formation in tri-metal Ti/Al/Nb composite

Tri-dissimilar Ti/Al/Nb multilayer composites were produced from Ti, Al and Nb sheets by solid state diffusion bonding through hot pressing and subsequent hot rolling. By annealing the produced composites at temperatures higher than the melting point of Al, the microstructures consisted of dispersed intermetallic particles in an Al matrix were obtained. The microstructural characterizations were performed by scanning electron microscope, X-ray diffraction and transmission electron microscope. Also, the interactions between Ti, Al and Nb were studied by observation of the microstructural evolutions during annealing at different temperatures (700-760 degrees C) and durations (30-120 min). Results showed that there are three distinct regions in the diffusion reaction zone (DRZ). In the first region, irregular shaped and angular particles were observed, which are distributed in a wide region of Al matrix. Prolonged annealing times caused formation of a dense intermetallic compound (Ti, Nb)Al-3 layer. The second region has consisted of only Al matrix and in the third region, TiAl3 spherules were formed and expelled into the liquid by new TiAl3 spherules and, the composition of these particles is changed to (Ti,Nb)Al-3 after prolonged annealing times. (C) 2018 Elsevier B.V. All rights reserved.