AISI 9310 nickel-chromium-molybdenum alloy steel is used extensively in military helicopter rotor shafts and gears. This reliable alloy provides excellent fatigue life combined with high hardness, elastic modulus, and tensile strength. However, to facilitate rapid speed changes of variable drive systems in high-performance rotorcraft, these steel components must weigh less and have lower rotational inertia. Ultramet will develop and demonstrate a material system consisting of continuous alumina fiber-reinforced 9310 steel. Relative to the unmodified alloy, this material system will offer reduced weight, increased strength, and increased stiffness while maintaining the excellent heat treatment properties and hardening schedules of 9310 steel. The composite will be lighter than the base alloy by 1523%, possess significantly higher specific strength and stiffness, maintain comparable corrosion resistance, and allow the continued use of proven 9310 steel. The composite will be produced using an innovative variant of Ultramet's rapid, low-cost pressureless melt infiltration technology previously demonstrated for fabrication of fiber-reinforced ceramic matrix composites.