Effect of Ti, Sc and Zr additions on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-2Cu alloys

Abstract

Al-Zn-Mg-Cu alloys (7xxx) belong to wrought aluminum alloys with high strength and toughness, which are widely used in aerospace and transportation fields [1,2] . Al-Zn-Mg-Cu alloys are generally formed through wrought process, which is much more expensive than the alternative casting route. However, Al-Zn-Mg-Cu alloys prepared by traditional casting methods are prone to casting defects such as shrinkage porosity and shrinkage cavities, which will deteriorate the mechanical properties of the alloys [3,4] . The semisolid metal processing technology discovered in 1971 provides the possibility for the direct casting of Al-Zn-Mg-Cu alloys [5] . This is because the semisolid