The theory of stress fields can be applied to various strengthening mechanisms for materials. Stress fields can be created by adding different sized atoms to the lattice (solute strengthening). If a smaller atom is added to the lattice a tensile stress field is created. The atomic bonds are longer due to the smaller radius of the solute atom. Similarly, if a larger atom is added to the lattice a compressive stress field is created. The atomic bonds are shorter due to the larger radius of the solute atom. The stress fields created by adding solute atoms form the basis of the material strengthening process that occurs in alloys.