Zn、Mg和Cu元素对Al-Zn-Mg-Cu-Zr-Er铝合金铸态组织及性能的影响

Influence of Zn, Mg and Cu Elements on As-cast Microstructure and Properties of Al-Zn-Mg-Cu-Zr-Er Aluminum Alloy

采用OM、SEM、EDS、XRD、硬度和导电率测试研究了Zn、Mg和Cu元素对Al-Zn-Mg-Cu-Zr-Er铝合金铸态组织及性能的影响。结果表明:合金的铸态组织均为典型的树枝晶,主要由α-Al基体、粗大的非平衡共晶相(AlZnCuMg四元相)、细小弥散的MgZn2相及少量的Al2Cu相组成。随着Zn、Mg和Cu含量的增加,非平衡共晶的数量和体积分数增加,枝晶臂间距变窄,且非平衡共晶相的厚度增加。同时,提高Zn、Mg和Cu元素含量,合金硬度增加,导电率下降,其中Mg含量增加对其影响最大。这些与JmatPro热力学相图计算结果及第二相的理化性能相吻合。

The influences of Zn,Mg and Cu elements on as-cast microstructure and properties of the Al-Zn-Mg-Cu-Zr-Er aluminum alloy were investigated by OM,SEM,EDS,XRD,hardness and conductivity testing.The results show that the as-cast microstructure of the alloy is typical dendrite,which is mainly composed ofα-Al matrix,coarse non-equilibrium eutectic phase(Al ZnCuMg quaternion phase),fine and dispersed MgZn2 phase,and a small amount of Al2Cu phase.With the increase of Zn,Mg and Cu contents,the number and volume fraction of the non-equilibrium eutectics increase,the dendrite arm space is narrowed,and the thickness of the non-equilibrium eutectics increases.At the same time,by increasing the contents of Zn,Mg and Cu,the hardness of the alloy increases and the conductivity decreases.Meanwhile,the increase of Mg content has the greatest impact on it.Those are consistent with the computing results of JmatPro thermodynamic phase diagram and the physicochemical properties of the second phase.