Densification behavior and the interfacial reaction of Ti/β-Ti laminated composite by spark plasma sintering

Ti/β-Ti laminated composite, which exhibits an exceptional combination of the good ductility of pure Ti and the high strength of the β-Ti alloy, has been extensively applied for biomedical applications. Here, we investigated the densification behavior of the pure Ti layer, β-Ti layer (Ti-15Mo layer), and laminated composite during the fabrication by spark plasma sintering at various sintering temperatures. The experimental results demonstrated that the majority of pores close to sintering necks could be eliminated by sintering at a temperature above 850 ℃, and both the Ti layers and Ti-15Mo layers achieved full densification. When the sintering temperature is below 700 ℃, the sintering is probably achieved by a mechanism of dislocation-climb at low compress stress and by a grain boundary sliding at high compress stress. However, the sintering was likely progressed by the dislocation-climb at 750–800 ℃ and the grain boundary sliding above 850 ℃, respectively. Besides, the influence of sintering temperature on the interfacial characteristics was investigated. The thickness of the interfacial layer was increased from 3 µm to 30 µm with the increase of sintering temperature. An α + β dual-phase structure is formed in the interface layer. The formation of α′ phase and ω phase at the interface of the composite at 1000 ℃ increased the microhardness of the interface, which is harder than the pure Ti and Ti-15Mo alloy.