Solid State Bond
In a Solid State Bond (also called thermo-compression Bond), dissimilar materials with dissimilar grain structure, e.g. molybdenum to tungsten, are joined using a very short heating time, high weld energy, and high force. There is little melting and minimum grain growth, but a definite bond and grain interface. Thus the materials actually bond while still in the 'solid state'. The bonded materials typically exhibit excellent shear and tensile strength, but poor peel strength.
For more information about the resistance welding process read our Fundamentals of Resistance Welding.