微量元素含量对Al-Zn-Mg合金组织与性能的影响

Effects of microelement content on microstructure and properties of Al-Zn-Mg aluminium alloy

通过光学显微镜、扫描电镜、透射电镜、强度实验、冲击韧度实验、应力腐蚀实验、剥落腐蚀实验及极化曲线测试,研究不同微量元素(Cr、Mn、Ti、Zr、Cu)含量添加对Al-Zn-Mg铝合金组织、力学性能与腐蚀性能的影响。结果表明:较多的微量元素使得合金内部第二相析出密度变大,对亚晶界/晶界的迁移起阻碍作用而未诱发粒子形核,提升合金抑制再结晶的能力,从而保持细小晶粒及亚晶组织,合金的抗拉强度提升69 MPa,应力腐蚀开裂延迟了108 h。但同时微量元素使得Al Fe Mn Cu等粗大的第二相增多,使自腐蚀电位正移、腐蚀电流密度变小,而塑性、韧性及耐剥落腐蚀性能均有所下降。

The effects of different microelement （Cr, Mn, Ti, Zr, Cu） contents on the microstructure, mechanical properties and corrosion properties of Al-Zn-Mg aluminium alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile test, impact properties test, stress corrosion and polarization curve measurement. The results show that a little more microelement added to the Al-Zn-Mg aluminium alloys effectively delays the mergence and growth of the sub-grain during the recovery process, inhibits the recrystallization capability of A1 matrix, and significantly enhances the mechanical properties and resistance to stress corrosion increasing the tensile strength by 69MPa and postpones the moment of stress corrosion cracking for 108 h. However, the present of more trace elements makes wider distribution of the slightly larger size AlFeMnCu phase generate inside the alloy, makes the matrix as the anode form a microcell, and the surface pitting, plasticity, toughness and corrosion resistance decrease.