Microstructure and mechanical properties, with emphasis in impact toughness behaviour, of two multilayer composites have been investigated. The multilayer materials are constituted by thirteen layers of high strength Ti–6 Al–4 V alloy. Stacked layers have been successfully joined by diffusion bonding considering two processing temperatures, 750 and 900 °C. The proportion of α/β phase in the microstructure during diffusion bonding process determines the presence of pores at the interface, and therefore the mechanical properties of the composite material. Higher bcc β phase proportion during diffusion bonding process at the highest temperature of 900 °C leads to high bonding degree, without noticeable toughness increase of the multilayer composite. In contrast, higher proportion of harder hcp α phase at 750 °C makes difficult the healing of interfacial pores, decreasing interfacial toughness and leading to a toughness value of the multilayer composite seven times higher than the reported value for the as-received Ti–6 Al–4 V alloy.

Financial support from MICINN (Project MAT2009-14452)

Peer reviewed