Light weight fan blades for turbofan jet engines are disclosed. The fan blades may be fabricated from an aluminum alloy. To enhance the hardness of the leading edge of the fan blade, a titanium sheath may be attached to the leading edges of the fan blades. To prevent galvanic coupling between the titanium and the aluminum, a polymeric liner may be disposed between the protective titanium sheath and the aluminum fan blade. The liner may be fabricated from a polymer material, such as a polyimide or another high performance polymer.