Influence of Mg content on the microstructure and mechanical properties of w(Zn)=11%ultra-high strength aluminum alloy
The influence of Mg content on the microstructure and mechanical properties of w(Zn)=11%ultra-high strength aluminum alloy has been systematacially investigated.The ingot microstructure is dendritic structure,the average grain size is 170-240 μm,and coarse α(Al)+T(AlZnMgCu)eutectic phase exists.After homogenization annealing,coarse T phase dissolves into matrix completely in w(Mg)<1.75%alloys,while a slight a-mount of T phase is retained in w(Mg)>2.0%alloys.After hot extrusion and solution treatment,the T phase is dissolved completely,the microstructure is fiber band,the average fiber band width is 24.2-35.4 μm,and the recrystallization fraction is 1.2%-6.5%.Af-ter peak aging treatment,high-density strengthening precipitates in matrix are mainly GP zone and η′phase with size of 2-5 nm.As the Mg content rises,the yield strength increa-ses from 687 MPa to 782 MPa,and the tensile strength increases from 717 MPa to 795 MPa,while the elongation decreases from 12.5%to 9.3%.In w(Zn)=11%ultra-high strength aluminum alloys,the strengthening precipitates amount is proportional to Mg content,so the alloy strength increases with Mg content rising.
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