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7000 Al-Zn-Mg-Cu ultra-high - strength aluminum alloy with a high specific strength and hardness , easy processing, good corrosion resistance and higher fracture toughness , etc. , are widely used in aviation, aerospace and military fields , but the Department of the shortcomings of the alloy is not good the tissue thermal stability stability . This article looks at today 's ultra - high - strength aluminum alloy trends , combined with Fund for Nature project in Inner Mongolia , to use the service target of 100 ℃ ~ 300 ℃ , Sc and Zr microalloying elements , the main heat treatment of Al-Zn-Mg- Cu alloys and organizations thermal stability . Al-12Zn-2.4Mg-1.1Cu-0.3Sc-0.2Zr-0.3Ni alloy prepared by spray deposition technology , hardness testing and differential thermal analysis methods , by means of optical microscopy , scanning electron microscopy, transmission electron microscopy and XRD analysis studied by means of heat treatment on the mechanical properties and microstructure of the experimental alloy . The results show that : Round dusting particle diameter of about 3 to 15 μm , the alloy deposited green tissue uniform equiaxed grain , average grain size of 15μm . Deposited billets after 0 ~ 24h annealing treatment at 460 ℃ grain size is still maintained at about 15μm , and the hardness values ??of between 57 ~ 60HRB ; extrusions at 470 ° C , respectively 480 ° C and 490 ℃ 0 ~ 2h solution heat treatment, the hardness values ??of the alloy is between 61 ~ 67HRB ; Sc , Zr microalloyed the alloy deposited billet, extrusion billet organization maintaining good thermal stability . The deposition billet annealing process 460 ℃ insulation 12h, and insulation 0.5h after the extrusion billet 480 ° C solution treatment in the hardness of the highest value 66.68HRB . The solidification process of spray deposition , the experimental alloys , precipitation of the light and dark LI2 newborn A13 ( sc , Zr ) particles , the size in the 100 to 200 nm . Extrusion billet 480 ~ ℃ / 2h 120 ~ ℃ / 24h aging treatment , precipitation of α (Al ) base body was hoof -shaped the LI2 -type secondary A13 (Sc , Zr) particles , Al (Sc, Zr) particles substantially no grew up, the particle size of 7 to 12 nm . Alloy extrusion billet 480 ° C / 2h after solution treatment , aging treatment at 110 ~ ~ ℃ ~ 150 ℃ , the hardness of the alloy was similar to the \after the the alloy highest hardness value 73.22HRB. η ' phase and a small amount of GP zones together lead to 480 ° C ~~ ~~ , / h 120 ~~ of C / 24h the hardness value 67.1HRB the important reasons .
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