The mechanical properties of the Ti-6Al-7Nb alloy, used to manufacture high-strength prostheses, are highly dependent on its microstructure. This work presents the microstructural changes of this alloy under isothermal hot working. It is shown that microstructure is strongly affected by strain rate, temperature and strain. The possible precipitation of intermetallic phases is also evaluated. To define the best processing conditions, compression tests were performed at temperatures varying from 750 to 1030 ºC and deformation speeds of 0.01, 0.1 and 1 mm/s. Tests were carried out in the α+β and β phase regions. Experimental results showed that the best microstructure (recrystallized with equiaxial refined white α grains and acicular dark grains within a β-transformed matrix) was obtained in tests at 950 ºC and 0.01 mm/s. NOTATION e engineering strain [mm/mm] v deformation speed [mm/s] σ e engineering stress [MPa] σ r true stress [MPa]

This investigation reports the results of linear polarization of hot upset Ti-6Al-7Nb bar samples. Current-potential curves recorded in Hank’s solution were analyzed by correlating characteristics of passivation and microstructures obtained after processing. Results have shown that it is important to select temperature process and deformation rate as parameters when more noble potential values are required. Low deformation rate facilitates the formation of beta phase that is retained in the structure at room temperature shifting the corrosion potential to more positive values. However, samples hot compressed from 750°C to 1030 °C showed passive layer stability over a wide range of potentials extending from -0.15 V to 1.75 V vs SCE . Furthermore, passive films grown onto the Ti-6Al-7Nb samples surfaces have shown no sign of rupture for the processing conditions selected for this study

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