Microstructures and Mechanical Properties of Melt Extruded Al-Cu Alloys

Abstract

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. The effects of various process parameters, such as melt temperature and extrusion ratio, on the extrusion behavior of Al-Cu alloys in the semisolid state were investigated. Mechanical properties of the melt extruded Al-Cu alloy were measured and its characteristics are compared with the microstructure and copper contents in the alloy. Al-Cu alloys were successfully extruded after squeezing out of liquid during the melt extrusion with smaller force (60 Mpa) compared to the solid extrusion. Al-Cu alloys bar with the mean grain size of 200 μm was fabricated by melt extrusion; however, the mechanical properties have nothing to do with the extrusion ratio. The squeezing out of liquid was get lead to the segregation of the alloys and was affect on the mechanical properties.