We just started to collaborate with Pratt & Whitney to investigate the mechanical properties of grain boundaries of Ti alloys ($30,000)! This new project will study (1) how diffusion bonding influence the mechanical behavior of grain boundaries (impurity segregation and abnormal growth of weak beta-phase) and (2) how the mechanical behavior of twist boundary is affected by the misorientation and the imposed strain rate. Understanding of mechanical behavior of grain boundary will be crucial for the improvement of fatigue resistance of Ti alloys.