Ren Jian, Wang Richu, Peng Chaoqun, Feng Yan
School of Materials Science and Engineering, Anhui University of Technology, Maanshan, 243000, China.
School of Materials Science and Engineering, Central South University, Changsha, 410083, China; National Key Laboratory of Science and Technology for National Defence on High-strength Structural Materials, Central South University, Changsha, 410083, China.
Micron. 2021 May;144:103015. doi: 10.1016/j.micron.2021.103015. Epub 2021 Jan 22.
In this paper, two kinds of Al-Zn-Mg-Cu alloys with high Zn content (Al-8.1Zn-2.0Mg-2.3Cu-0.12Zr-0.12Sc and Al-10.5Zn-2.5Mg-1.5Cu-0.12Zr-0.12Sc) are fabricated by powder hot extrusion. Microstructure and mechanical properties are investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and tensile tests. The results show that the formation of ultrafine grains and homogeneous second phases in as-extruded alloys is achieved by perfect metallurgical bonding during severe plastic deformation. After the optimal solution treatment and peak aging treatment, the strength of the two alloys reaches up to 734 MPa and 802 MPa, and the elongation is 9.8 % and 5.3 %, respectively. The excellent mechanical properties are attributed to the grain boundary strengthening, precipitation strengthening and homogenous microstructure. The element content has little effect on the grain size of the powder hot-extruded Al-Zn-Mg-Cu alloy, but high Zn and Mg contents can improve the density of strengthening phases while low Cu content can reduce the difficulty of solution treatment by inhibiting the precipitation of S(AlCuMg) phase.
本文采用粉末热挤压工艺制备了两种高锌含量的Al-Zn-Mg-Cu合金（Al-8.1Zn-2.0Mg-2.3Cu-0.12Zr-0.12Sc和Al-10.5Zn-2.5Mg-1.5Cu-0.12Zr-0.12Sc）。通过光学显微镜（OM）、扫描电子显微镜（SEM）、X射线衍射（XRD）、透射电子显微镜（TEM）和拉伸试验对其微观结构和力学性能进行了研究。结果表明，通过严重塑性变形过程中的完美冶金结合，在挤压态合金中实现了超细晶粒和均匀第二相的形成。经过最佳固溶处理和峰值时效处理后，两种合金的强度分别达到734 MPa和802 MPa，伸长率分别为9.8%和5.3%。优异的力学性能归因于晶界强化、析出强化和均匀的微观结构。元素含量对粉末热挤压Al-Zn-Mg-Cu合金的晶粒尺寸影响较小，但高锌和镁含量可以提高强化相的密度，而低铜含量可以通过抑制S(AlCuMg)相的析出降低固溶处理的难度。
