In aerospace and aeronautical applications, significant improvement of energy efficiency can be achieved by the deployment of titanium-based alloys. In Boeing 787 engines, the use of turbine blades made with -TiAl alloys instead of nickel-based superalloys provides 20% fuel saving and 80% reduction of NOx emission with a weight reduction of 200 pounds per engine. However, a number of fundamental issues remain unclarified, which results in either the degradation of mechanical properties or the reduction in service life. Employing state-of-the-art modeling tools, we have looked into several key atomic processes in titanium alloys, covering point defects, dislocations, twins, grain boundaries, etc. These modeling investigations have received strong supports from experiments and thus have enriched our understanding on the mechanical behaviors of titanium alloys, with which performance improvement can be achieved for better energy efficiency.