Microstructure and tensile properties of squeeze cast aluminium alloy A380 containing Ni and Sr addition

Aluminum alloy A380 was alloyed and modified with the addition of transition metal, nickel (Ni) and alkaline earth element, strontium (Sr). Squeeze casting was employed to cast the modified A380 under an applied pressure of 90 MPa. Tensile properties and microstructure of the Ni- and Sr-containing alloy are compared with those of the conventional alloy A380 in as-cast condition. The results of tensile testing indicate that the Ni- and Sr-containing A380 alloy exhibits a significantly improvement on tensile properties, specifically ultimate tensile strength and yield strength. The as-cast microstructures of both conventional and Ni- and Sr-containing alloys are observed by an optical microscope and further analysed with a scanning electron microscope. Examination of the analysed microstructures manifests that the presence of Ni-containing intermetallic phases, and the modified eutectic Si phase with refined morphologies due to the Sr addition should be responsible for the considerable enhancement on the as-cast strengths of the squeeze cast Ni- and Sr-containing alloy over those of the conventional A380 alloy.