thixoformage

CONT: Certains alliages métalliques, préparés dans des conditions particulières, présentent un caractère thixotrope à l'état semi-liquide. Cette propriété leur confère un comportement particulier qui présente un intérêt pour les opérations de formage. Le thixoformage constitue l'une de ces opérations, rendues possibles par la connaissance et la maîtrise croissante des caractéristiques et de la mise en œuvre des alliages thixotropes. Le thixoformage recouvre deux procédés de formage des matériaux thixotropes : le moulage (ou thixomoulage) et le forgeage (ou thixoforgeage).

CONT: The Thixoforming Group in the Department of Engineering Materials at the University of Sheffield undertakes research and development into the forming of alloys and composites in the semi-solid state (SSM). This process is commonly called thixoforming (thixocasting or thixoforging) and possesses some of the advantages of both casting and forging. Initially the material behaves in the semi-solid condition like a solid (it can be picked up and holds it shape unsupported), but when injected into a die it flows like a liquid to take the form of the die accurately, as in die-casting. However, the structure is fine and uniform, virtually free of porosity, and the product may be heat-treated to give mechanical properties superior to those of castings. The thermal shock to the die is less than that given by a liquid, which means that higher melting point alloys - which cannot easily be diecast - may nevertheless be thixocast.