Extrusion behavior of Al-Cu alloys in the semisolid state

Melt-extrusion is a new fabrication process with the characteristics of both casting and extrusion. In this process, a metallic melt which is poured and solidified up to semisolid state in the container can be directly extruded through the die exit to form a product of bar shape without other intermediate processes. In this study, the fabrication characteristics of the process were evaluated with various process parameters, such as extrusion temperature, initial ram velocity and initial microstructure. Al-Cu alloys were successfully extruded after squeezing out of liquid during melt-extrusion with smaller force compared to the solid extrusion. The extrusion temperature and initial ram velocity increase with increasing volume of squeezed liquid. The extrusion pressure tended toward decrease with increasing extrusion temperature and decreasing initial ram velocity. The amount of squeezed liquid was reduced by treatment of grain refiner into Al-Cu melt.