Interface evolution and shear strength of Al/Ti bi-metals processed by a spark plasma sintering (SPS) apparatus

Microstructural evolution of the Al/Ti bi-metal interface during heat treatment in a spark plasma sintering (SPS) apparatus was investigated under various conditions for the first time. A mechanism of interfacial layer growth was suggested based on the results of SEM, TEM and X-ray diffraction analysis. A continuous TiAl3 intermetallic layer was formed at the Al/Ti interface even after a processing time as short as about a minute. The TiAl3 layer grew mainly into the Ti part, while only a few individual grains grew into the Al part. Evolution of the interlayer was determined by Al diffusion through the (TiAl3/TiAl3) grain boundary. The activation energy of the process was 140 kJ/mol. The shear strength of the interface in the Al/Ti bi-metal was determined after various heat treatments. The shear strength of the bi-metal was limited by the properties of aluminum, with no effect of interlayer thickness or current mode and pulse pattern of the SPS treatment being detected. (C) 2016 Elsevier B.V. All rights reserved.