High-temperature microstructural characteristics of a novel biomedical titanium alloy

In this study, the high-temperature microstructural characteristics of the Ti-5Al-1Sn-1Fe-1Cr (Ti-5111) alloy were determined by optical microscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectrometry. During solution treatment between 800 and 1000 degrees C, the phase transformation sequence of the alloy was found to be (alpha+beta) -> (alpha + alpha' + beta), (alpha + alpha' + alpha '' + residual beta) -> (alpha' + beta). The residual beta phase subsequently transforms to the alpha '' phase during quenching. The driving force for this transformation is the cooling rate. The martensite starting point (Ms) and beta transus temperature of the Ti-5111 alloy are nearly 860 and 960 degrees C, respectively. These values are lower than those of the Ti-6Al-4V alloy. Moreover, it is believed that the concentration of Al in alpha' martensite plays a crucial role in the formation of the twin-type martensite. (C) 2010 Published by Elsevier B.V.