Microstructure, Phase Transformation, Mechanical Behavior, Bio-corrosion and Antibacterial Properties of Ti-Nb-xSn (x=0, 0.25, 0.5 and 1.5) SMAs

Porous Ti-Nb-xSn shape memory alloys (SMAs) are fabricated by microwave sintering technology. The microstructures exhibit needle-like morphologies, ((N)) (normal straight and crossed needles along with needle-like morphology that resembles spaghetti or irregular lines with -phases in between) as well as plate-like morphologies [normal straight plate-like morphology, and dendritic plate-like morphology, ((D))]. Increases in Sn addition significantly induce an increase in the density of the -phase. XRD patterns exhibited three phases, namely the -main phase with smaller intensities of and . Further, the addition of 0.25% Sn led to more effective improvement in the intensity of the -phase compared with 0.5% and 1.5% Sn addition. Additions of Sn also enhanced the fracture strength and its corresponding strain along with the shape memory effect (SME), where the best enhancement was achieved at 0.25% Sn. The corrosion rate (Ri) was reduced by rising Sn content, while both corrosion resistance and antibacterial zones were increased. The lower elastic modulus, as well as the robust mechanical properties and bioactivity, made these SMAs rather suitable for biomedical application purposes, where the low elastic modulus had value in terms of avoiding the problem of stress shielding.