Zhang Bingrong, Zhang Lingkun, Wang Zhiming, Gao Anjiang
School of Mechanical and Automotive Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
Conglin Group Co.Ltd. Longkou, Yantai 265705, China.
Materials (Basel). 2020 Feb 1;13(3):647. doi: 10.3390/ma13030647.
In order to obtain high-strength and high-ductility Al-Si-Cu-Mg alloys, the present research is focused on optimizing the composition of soluble phases, the structure and morphology of insoluble phases, and artificial ageing processes. The results show that the best matches, 0.4 wt% Mg and 1.2 wt% Cu in the Al-9Si alloy, avoided the toxic effect of the blocky AlCu on the mechanical properties of the alloy. The addition of 0.6 wt% Zn modified the morphology of eutectic Si from coarse particles to fine fibrous particles and the texture of Fe-rich phases from acicular β-Fe to blocky π-Fe in the Al-9Si-1.2Cu-0.4Mg-based alloy. With the optimization of the heat treatment parameters, the spherical eutectic Si and the fully fused β-Fe dramatically improved the ultimate tensile strength and elongation to fracture. Compared with the Al-9Si-1.2Cu-0.4Mg-based alloy, the 0.6 wt% Zn modified alloy not only increased the ultimate tensile strength and elongation to fracture of peak ageing but also reduced the time of peak ageing. The following improved combination of higher tensile strength and higher elongation was achieved for 0.6 wt% Zn modified alloy by double-stage ageing: 100 °C × 3 h + 180 °C × 7 h, with mechanical properties of ultimate tensile strength (UTS) of ~371 MPa, yield strength (YS) of ~291 MPa, and elongation to fracture (E%) of ~5.6%.
为了获得高强度和高延展性的Al-Si-Cu-Mg合金，本研究聚焦于优化可溶相的成分、不溶相的结构和形态以及人工时效工艺。结果表明，在Al-9Si合金中0.4 wt%的Mg和1.2 wt%的Cu的最佳匹配，避免了块状AlCu对合金力学性能的有害影响。在Al-9Si-1.2Cu-0.4Mg基合金中添加0.6 wt%的Zn，使共晶硅的形态从粗颗粒变为细纤维状颗粒，富铁相的织构从针状β-Fe变为块状π-Fe。随着热处理参数的优化，球形共晶硅和完全熔合的β-Fe显著提高了抗拉强度和断裂伸长率。与Al-9Si-1.2Cu-0.4Mg基合金相比，0.6 wt% Zn改性合金不仅提高了峰值时效的抗拉强度和断裂伸长率，而且缩短了峰值时效时间。通过双级时效，0.6 wt% Zn改性合金实现了以下更高抗拉强度和更高伸长率的改进组合：100 °C×3 h + 180 °C×7 h，其力学性能为抗拉强度（UTS）约371 MPa，屈服强度（YS）约291 MPa，断裂伸长率（E%）约5.6%。
