Disclosed is a method of making an integrally bladed rotor. According to the method, a titanium alloy rotor disk with 15-50% by volume of primary alpha grains with a grain size less than 10 μm and secondary alpha grains comprising widmanstatten grains with a grain size less than 1.0 μm is subjected to thermal processing. After thermal processing, a blade having an airfoil and a base is positioned such that a base surface is in contact with an outer rim surface of the disk. Heat, pressure, and motion are applied between the blade and the disk to friction weld the base surface to the disk outer rim surface.