Study On The Modification And Refinement Mechanism Of 7xxx Series Aluminum Alloys With Ceramic Particles/Al Alloys Composite Inoculants

7xxx series(Al–Zn–Mg–Cu) super-high strength aluminum alloy is one of the most important engineering alloys and has been applied extensively in aircraft structures as a result of its excellent combination properties, high strength, low density, high toughness, corrosion resistance and outstanding workability. In order to provide scientific and practical basis for developing new inoculants,optimizing alloy component and making an appropriate heat treatment process,the new inoculants and the alloy component,heat treatment process, microstructure and properties of 7xxx alloy were investigated.In this study, a new Al3Ti-TiB2/Al composite inoculants that containing TiB2 and Al3 Ti particles was prepared through the improved component and optimized preparation process on traditional Al-5Ti-1B. Moreover, these particles can be excellent nucleation core and this new inoculants show a good refining effect. And pure aluminium grain can be refined to about 150 μm. Two kinds Al-Zn-Mg-Cu alloys of different components were designed on the basic of variable Cu content. Al-Zn-Mg-Cu alloys were refined with prepared inoculants. Heat treatment process was optimized and the microstructure of alloys at all stages was characterized and analyzed.The mechanical properties of Al-Zn-Mg-Cu alloys were tested. Excellent mechanical properties were obtained, which the hardness is about 211 HV, the strength is about 758 MPa and the elongation is about 7%. Refinement and reinforcement mechanism were studied and the correspondence between micro and macro was indicated according to theoretical analysis and calculation.