Research On New Type Of Ultra High Al-Zn-Mg-Cu Alloy

With the development of high technology fields of aeronautics and astronautics,requirements for the property of ultra high strength aluminum alloy to the higher.Howerver,conformance to requirements mainly is Al-Zn-Mg-Cu alloy.With the Zn、Mg、Cu element content increase in a certain range,the strength of Al-Zn-Mg-Cu alloy can improve.Howerver,when the Zn content reaches 11%(wt),the content of Mg and Cu can not reach 3%in the reported news,the purpose of this article is to explore the property of ultra high Al-Zn-Mg-Cu alloy,which is based on the Zn content of 11%,the content of Cu and Mg in excess of 3%,this is important for developing better property ultra high Al-Zn-Mg-Cu alloy.The laboratory utilizes water-cooled copper casting and semicontinuous casting to produce several ultra high Al-Zn-Mg-Cu alloy,which Zn content is 11%,Mg content reaches 5%,Cu content reaches 4%,which utilizes optical microscopy、scanning electron microscopy and energy disperse spectroscopy、differential thermal analysis、mechanical testing and some other means to research the foundry technology、rolling technology、as-cast structure and microstructure after heating treatment.microstructure and property of plates after heating treatment.The main results are as follows:(1)Adopting small water-cooled copper equipment with controlling the rate of the liquid lever produces high alloy content of Al Zn Mg Cu ingot casting with the size 200mm×120mm×36mm,the quality of ingot casting is preferably.(2)The over burnt temperature of three ultra high Al-Zn-Mg-Cu alloy ingot casting is 475 ℃ about,they have a large amount of residual phase after 465℃×48h homogenization treatment;the ingots after medium temperature pretreatment,they can be rolled into plates with 10%-20%reduction rate;the over burnt temperature of plates is also 475℃ about,the residual phase can not be eliminated after solution treatment.(3)The solubility of alloying element of three ultra high strength aluminum alloy plates(Al-11Zn-5Mg-2.5Cu-0.12Zr(E1 alloy).Al-11Zn-5Mg-2.5Cu-0.12Zr-1Mn-0.3Cr(E2 alloy)、A1-11Zn-5Mg-4Cu-0.12Zr(E3 alloy))reach the limit after 465℃ ×30min solution treatment,harding and 120℃×24h peak aging treatment;the strength of extension、yield strength、ductility of E1、E3 plate is634.739MPa、636.177Mpa;606.504MPa、601.883MPa;4%、6%.The strength of extension、yield strength、ductility of E3 plate at 250℃is 350.774MPa;333.736MPa;4%.Based on 120℃×24h aging then 300℃×6h aging,The strength of extension、yield strength、ductility of E1 and E3 plate at 250℃ is 194.202MPa、189.042MPa;169.153MPa、148.262MPa;11.36%、11.56%。...