Once the proper temperature and composition is achieved, the melt is cast. Castings can be divided into two types, depending on the subsequent processing steps. The first type is shape casting, which takes advantage of the fluidity of liquid metal to form complex shapes directly. Because of the complexity of their part geometries, these castings generally cannot be mechanically worked to a significant degree and any changes in microstructure or properties must be achieved during solidification or through heat treatments afterwards Casting, crystal growth, atomization, welding, etc. Metals and polymers can also be processed from powders.
Densification follows, usually by sintering.
There are essentially two basic methods of consolidating powders. Vapor source methods require a vacuum to transport the gaseous source of atoms to the surface for deposition. It generally involves the use of a large force to deform the material. Many techniques heat the material to reduce the force needed to deform it. Sometimes a mold is used to define the shape.