Weight reduction is one of the most important objectives in the aerospace industry. Reduction in the overall weight of the aircraft contributes to fuel savings, which means a drop in total operational cost. In the aerospace industry, fuel cost amounts to about 35-40% of the total operation expense. A 30% reduction in weight of the aircraft saves about 20% of fuel, nearly a 10% reduction in operation cost. Structural materials with low density and good mechanical properties are desirable in aerospace applications.