固溶处理对喷射沉积含镍高强Al-Zn-Mg-Cu合金组织和性能的影响

Effects of solid-solution on microstructure and property of high strength spray deposited Al-Zn-Mg-Cu alloy modified by Ni

采用喷射沉积技术制备Al-8.2Zn-2.2Mg-2.1Cu-0.14Zr-1.0Ni(质量分数,%)合金沉积坯,沉积坯经热挤压变形后在不同温度固溶处理,然后在(130℃,24h)条件下进行T6时效处理。通过对组织和性能分析,确定最佳固溶处理工艺。结果表明:加入1%Ni后沉积坯晶粒细小均匀,平均直径为15μm左右;在晶界和基体中有富Ni的Al3Ni2、Al7Cu4Ni、MgNi2第二相粒子出现,这些粒子在合金中主要起到弥散强化的作用;溶质元素Zn、Mg、Cu的沉淀析出强化与球形富Ni粒子的弥散强化共同作用是使含1%Ni-7055铝合金具有高强度高塑性的主要因素;经挤压变形(λ=3)和(475℃,1.5h)+(130℃,24h)热处理后,合金管材纵向抗拉强度可达到690MPa、伸长率为9.6%、布氏硬度为HB192。

High strength Al-8.2Zn-2.2Mg-2.1Cu-0.14Zr-1.0Ni（mass fraction,%） alloys,which was produced by spraying deposition method（the Osprey process）,were heat treated at different solid-solutions,and all the aging treatments were at 130 ℃for 24 h.Microstructure characterization of the alloy was carried out by SEM,EDS and XRD,and the tensile properties of the alloy were tested.The result shows that many Ni-rich particles of Al3Ni2,Al7Cu4Ni and MgNi2,which provide a dispersive strengthening effect in the following solid-solution and ageing treatment,are dispersed both in grain-boundary and grain.The average grain size is approximately 15 μm.The remarkable strengthening while maintaining high levels of ductility is predominantly attributed to the precipitation hardening of solute elements and the dispersoid strength of spheroid Ni-rich particles.The highest ultimate tensile strength（UTS） for the pipe alloy（at an extrusion ratio of 3：1） is 690 MPa at a ductility of 9.6% after the optimized solid solution and T6 aging.