Interface property of dissimilar Ti–6Al–4V/AA1050 composite laminate made by non-equal channel lateral co-extrusion and heat treatment

Abstract

The purpose of this paper is to examine the effect of processing parameters and subsequent heat treatments on the microstructures and bonding strengths of Ti–6Al–4V/AA1050 laminations formed via a non-equal channel lateral co-extrusion process. The microstructural evolution and growth mechanism in the diffusion layer were discussed further to optimize the bonding quality by appropriately adjusting process parameters. Scanning electron microscopes (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) were used to characterize interfacial diffusion layers. The shear test was used to determine the mechanical properties of the interfacial diffusion layer. The experimental results indicate that it is possible to co-extrusion Ti–6Al–4V/AA1050 compound profiles using non-equal channel lateral co-extrusion. Different heat treatment processes affect the thickness of the diffusion layer. When the temperature and time of heat treatment increase, the thickness of the reaction layers increases dramatically. Additionally, the shear strength of the Ti–6Al–4V/AA1050 composite interface is proportional to the diffusion layer thickness. It is observed that a medium interface thickness results in superior mechanical performance when compared to neither a greater nor a lesser interface thickness. Microstructural characterization of all heat treatments reveals that the only intermetallic compound observed in the diffusion layers is TiAl3. Due to the inter-diffusion of Ti and Al atoms, the TiAl3 layer grows primarily at AA1050/TiAl3 interfaces.

Keywords

• Shear strength
• Co-extrusion
• Heat treatment
• Microstructure
• Intermetallic compounds