微量Ag对ZL114A铝合金组织和力学性能的影响

利用万能电子拉伸试验机、光学显微镜、扫描电子显微镜、球差校正场发射透射电子显微镜等研究微量Ag元素对ZL114A铝合金力学性能和显微组织的影响。结果表明:随着Ag含量的增加,合金的抗拉强度、屈服强度提高,伸长率无明显变化;当Ag含量提高到0.55%(质量分数)时,ZL114A铝合金的峰时效抗拉强度从351MPa提高到369MPa,屈服强度从309MPa提高到328MPa,伸长率从2.36%提高到2.93%。ZL114A合金组织的α-Al枝晶和共晶Si无明显变化;Ag含量的提高,促进了GP区形核质点数量增加,引起了β″数量密度增加。在高角度环形暗场扫描透射(HAADF-STEM)模式下观察到Ag原子分布在β″相中,抑制了Mg原子和Si原子在β″相中扩散,导致β″相尺寸减小。

Effect of minor Ag on microstructure and mechanical properties of ZL114A aluminum alloy

The effects of trace element Ag on the mechanical properties and microstructure of ZL114 A aluminum alloy were investigated by the universal electron tensile testing machine, optical microscopy, scanning electron microscopy and spherical aberration correction field emission transmission electron microscopy. The results show that the tensile strength and yield strength of the alloy are enhanced with the increase of Ag content. However, no significant impact on the elongation is observed with the addition of Ag. When the Ag content reaches 0.55%(mass fraction), the peak aging tensile strength, yield strength, and elongation of ZL114 A aluminum alloy increase from 351 MPa to 369 MPa, 309 MPa to 328 MPa, and 2.36% to 2.93%, respectively. There is no evidence of properties of α-Al dendrite and eutectic Si changing under the same condition. The increase of the Ag content promotes the amount of nucleation particles in GP zones, leading to the denser density of β″. Ag atoms are observed in the β″ phase under high-angle annular dark-field scanning transmission electron microscope(HAADF-STEM) mode, indicating that Ag atoms inhibit the diffusion of Mg atoms as well as Si atoms in the β″ phase and the size of β″ phase is reduced as a result.