Effects of Scandium Addition on Microstructure and Mechanical Properties of AA 7075 Aluminium Alloy

The most attractive properties of aluminum and its alloys which make them suitable for a wide variety of applications are their light weight, appearance, frabricability, strength, and corrosion resistance. Among aluminium alloys AA7075 alloy has many attractive properties compared to other alloy it is economical and versatile to use this is the reason it is very widely used in the aerospace, automobile and other industries. AA7075 aluminum alloys are important structural materials due to their high strength and increased strength to weight ratio. The effects of Sc addition on the microstructure and mechanical properties of the AA7075 wrought zinc alloy were investigated by using optical microscope, scanning electron microscopy, and tensile testing. The experimental results show that a minor Sc addition to AA7075 alloy has an obvious effect on the refinement of the microstructure of the AA7075 alloy. During casting, incomplete dynamic recrystallization occurs in all the alloys, and the recrystallized grains become much finer with increasing Sc addition. The ultimate tensile strengths of AA7075 evidently increase with the addition of Sc, but the elongations decrease. The AA7075 alloy with 0.23% (weight fraction) Sc addition is found to have the tensile strength of about 468.8 MPa and the yield strength of about 324.3 MPa. Further by T6 tempering heat treatment, the tensile strength of the alloy containing 0.23% Sc is increased to 485.8 MPa and yield strength 335.49 Mpa.