Thermal stability and annealing behaviour of ultrafine grained commercially pure titanium

Ultrafine grained (UFG) commercially pure titanium was fabricated by 8 successive passes of equal channel angular pressing (ECAP) via route B-C. The deformed structure was studied by transmission electron microscopy (TEM). The material was then annealed at a range of temperature (450-600 degrees C) for up to 6h. The microstructure evolution and the grain growth behaviour were investigated by electron back scattered diffraction (EBSD) technique. The UFG titanium was found to be thermally stable up to 450 degrees C. Based on the experimental results, the grain growth kinetics was characterized by calculating the grain growth activation energy (Q) and the time exponent (n). The value of Q was found to be close to the self diffusion activation energy of titanium, while n was found to be lower than the time exponent reported for grain growth in coarse grained pure titanium. (C) 2011 Elsevier B.V. All rights reserved.