Powder metallurgy may best defined by comparing it with “fusion metallurgy”. In fusion metallurgy a metal or alloy is melted and cast into a mold. The mold may have the shape of the desired product, in which case a casting is produced, or the shape of an ingot may be cast. The ingot is then formed into a wrought product by rolling, forging, extrusion, drawing, machining, etc. In powder metallurgy, metal powders, i. e. metals in finely divided form rather than molten metal, are the starting material. The powders are consolidated into products with a given shape. The basic steps in powder metallurgy are therefore powder production and powder consolidation.
The most common sequence in powder consolidation includes pressing the powder in a die into a compact and sintering the compact, which means heating it to a temperature below the melting point of the metal or alloy to give it the desired physical, mechanical and chemical properties. As in fusion metallurgy the consolidation process may .lead to a part with the desired final shape corresponding to a casting or to a compact corresponding to an ingot which must be further shaped by forming by forming.
