Ca对镁合金组织、力学性能和腐蚀性能的影响

Effect of calcium on microstructure, mechanical properties and corrosion resistance of magnesium alloy

研究了Ca对AZ91D镁合金显微组织、力学性能和腐蚀性能的影响。当AZ91D中加入的Ca含量大于1 0%时, β相(Mg17Al12 )减少, 并且在晶界上形成了网状分布的Al2Ca相。拉伸测试表明, 当加入Ca含量小于1%时, 可以提高合金的常温抗拉强度和延伸率, 继续增大Ca含量时合金的力学性能明显下降。当AZ91D中加入的Ca含量达到 1 0%时, 常温抗拉强度和延伸率较AZ91D分别提高了 8 2%和 29 3%, 并且腐蚀速率下降为AZ91D的 17 2%。其原因主要是由于形成了网状分布的Al2Ca相, 使镁合金的自腐蚀电位升高, 腐蚀电流密度降低, 从而阻碍了镁合金的腐蚀。

The effect of calcium on microstructure, mechanical properties and corrosion resistance of magnesium alloy was studied. When the addition of Ca is more than 1%, the β phase decreases and some reticular Al_2Ca phases form on grain boundaries. The tensile tests indicate that when the Ca addition is less than 1%, the ultimate strength and elongation of AZ91D alloy increase, but when the Ca addition is more than 1%, the strength and elongation of AZ91D alloy decrease. The ultimate strength and elongation of AZ91D alloy with the addition of 1% Ca respectively increase by 8.2% and 29.3%, and the corrosion rate decreases to 17.2%. This is mainly caused by the formation of reticular Al_2Ca phase, which acts as an effective barrier against corrosion and makes the corrosion potential increasing and the corrosion current density decreasing.