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采用拉伸性能测试、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、深腐蚀、定量金相等技术手段研究了铝铜合金中富铁相对合金力学性能及拉伸断裂行为的影响。结果表明:随着Mn含量的增大,高铁含量合金力学性能得到改善,这主要是由于富铁相的演变和T相的增多以及铸造缺陷减少有关。针状β-Fe是铝铜合金中危害最大的富铁相。在拉伸过程中,针状β-Fe容易引起应力集中,从而导致富铁相与α(Al)基体界面断裂失效。同时针状β-Fe作为裂纹的起源,裂纹将沿着纵向发生二次扩展。与针状β-Fe相比,汉字状的富铁相对性能危害性更小,这是由于裂纹将在汉字状的Al_mFe和α-Fe中的枝晶臂间产生偏转,从而有效阻止裂纹的扩展。与Al_mFe相比,α-Fe比Al_mFe危害更小。这主要是由于Al_mFe具有晶体缺陷,本身能承受拉应力更小,枝晶发达的α-Fe与铝基体的结合力更大,同时发达的枝晶臂可以更加有效抑制裂纹的扩展。
The mechanical properties and tensile fracture behavior of the iron-rich alloys were studied by means of tensile test, scanning electron microscopy (SEM), transmission electron microscopy (TEM), deep erosion and quantitative metallography. The results show that with the increase of Mn content, the mechanical properties of high-iron content alloy are improved, mainly due to the evolution of iron-rich phase and the increase of T phase and the decrease of casting defects. Needle-like β-Fe is the most harmful iron-rich phase in aluminum-copper alloys. During the stretching process, needle-like β-Fe tends to cause stress concentration, resulting in the failure of the interfacial fracture between the iron-rich phase and the α (Al) matrix. At the same time acicular β-Fe as the origin of the crack, crack will occur along the longitudinal secondary expansion. Compared with the acicular β-Fe, the Chinese character-like iron-rich relative performance is less harmful because the crack will deflect between the Chinese-shaped Al_mFe and the dendrite arm in α-Fe, thus effectively preventing the crack growth . Compared with Al_mFe, α-Fe is less harmful than Al_mFe. This is mainly due to Al_mFe crystal defects, itself can withstand tensile stress smaller, dendrite developed α-Fe and aluminum matrix binding force greater, while the developed dendrite arm can be more effective in inhibiting the expansion of cracks.