An airfoil defining a chordwise dimension, a spanwise dimension, a leading edge, a trailing edge, a root, and a tip, is generally provided. The airfoil includes a first material substrate defining a pressure side and a suction side. The first material substrate defines a plurality of discrete volumes extended from at least one of the pressure side or the suction side into the first material substrate. The plurality of discrete volumes is arranged at least partially along the chordwise dimension and a second material substrate different from the first material substrate is defined at least partially within the volume.