Sparingly Alloyed Al-Zn-Mg-Fe-Ni Alloys for Casting and Extrusion

Optimized alloy chemistry and heat treatment has been developed using sparingly alloyed Al-Zn-Mg-Fe-Ni type of alloys for casting and extrusion. These alloys eliminate the Cu in the original nickalyn type formulations and take advantage of the Al+AlFeNi eutectics. Elimination of the Cu improves both casting and extrusion response in the alloy. Castings produced using moderate cooling rates such as those typically found in permanent mold or chilled sand castings exceed ultimate tensile strengths of 450 MPa, and extruded properties exceeding 475 MPa. Heat treat cycles developed specifically for casting are key to the high mechanical strengths in that product form. Similar heat treatments can be used for extrusions to maximize yield strengths while maintaining ductility in excess of 10%.