(大连理工大学 材料科学与工程学院,大连 116024)
摘 要: 采用铸锭冶金工艺制备6种Gd含量不同的A1-Zn-Mg-Cu-Zr-xGd合金。采用金相观察、力学性能测试、扫描电镜、电子探针及透射电镜等分析手段,研究质量分数x,分别为0%、0.10%、0.15%、0.20%、0.25%和0.30%的Gd对基体合金铸态及时效态显微组织和力学性能的影响。结果表明:Gd含量对A1-Zn-Mg-Cu-Zr合金的微观组织和力学性能的影响显著,当Gd含量低于0.25%时,随Gd含量的增加细化效果、强度以及伸长率都增加;当Gd含量为0.25%时,铸态组织中基体晶粒最小,达到32 μm左右;此时T6态合金组织的强度和伸长率达到最高,抗拉强为624.54 MPa,屈服强度为595.00 MPa,伸长率为13.3%,且固溶组织具有良好的抗再结晶作用;而当Gd含量超过0.25%时,合金的微观的组织与力学性能变差。
关键字: A1-Zn-Mg-Cu-Zr合金;Gd;显微组织;力学性能
(School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China)
Abstract:Six kinds of Al-Zn-Mg-Cu-Zr-xGd alloys with different Gd contents were prepared by cast metallurgical process. The compositional dependence of the casting structure, tensile properties was investigated for Al-Zn-Mg-Cu-Zr-xGd alloys(x=0%, 0.10%, 0.15%, 0.20%, 0.25%, and 0.30%, mass fraction) by optical microscopy (OM), tensile test, scanning electron microscopy (SEM), electronic probe microanalysis (EPMA) and transmission electronic microscopy (TEM). The results show that, with the increase of Gd content, the structure and the mechanical properties of A1-Zn-Mg-Cu-Zr-Gd alloy are improved. When the alloy contains 0.25% Gd, the alloy gets the finest microstructure, with grain size of about 32 μm. And the maximum ultimate tensile strength and yield strength are obtained in peak-aged state, and the values are 624.54 MPa and 595.00 MPa, respectively at T6 while the elongation is 13.3%. The role of anti-recrystallization is obvious in the solution structure. However, when the content of Gd exceeds 0.25%, the microstructure and properties of alloy appear certain deterioration.
Key words: A1-Zn-Mg-Cu-Zr alloy; Gd; microstructure; mechanical properties