A matrix material dispersed with one or more susceptor structures can be formed into a feedstock for an additive manufacturing process. The one or more susceptor structures can be excited by an energy field such as an electric field, a magnetic field, an electromagnetic field, or any combination thereof, to produce heat. The heat that is produced can be transferred to the matrix material that surrounds the one or more susceptor structures to provide heat treatment to the matrix material. The heat treatment can improve the material and mechanical properties of three dimensional objects formed from the feedstock.