Tungsten copper block is an alloy that is made by pressing tungsten or tungsten carbide, sintering the pressed tungsten at a high temperature, and then infiltrating it with copper. Sintering is a metallurgic process by which a metallic powder is made into a coherent mass by heating without melting. The physical properties of both tungsten and copper make them not mutually soluble, meaning that one cannot be combined with the other, similar to the way oil and water will not mix. The alloy is made by dispersing the particles of one metal into a matrix or crystallized pattern of another. This makes tungsten copper's "micro-structure" or molecular shape that of a metal matrix composite and not of a true alloy.