The electrochemical kinetics of matrix precipitates -metastable MgZn₂ (ɳ′) and GP II zones towards environmentally assisted cracking (EAC) have been investigated using cathodic polarization tests and slow strain rate tests. Retrogression and re-aging treatment (RRA) and modified interrupted aging treatment (MA3) are employed to produce high fractions of ɳ′ and GP II zones respectively. The higher ɳ′ fraction resulted in a three times higher hydrogen evolution on the alloy, thus decreasing the elongation values in the cathodically charged and uncharged 3.5 wt pct NaCl solution. Furthermore, the gauge surface of the ɳ′ dominated alloy showed pitting along the grain boundaries in 3.5 wt pct NaCl solution and a high amount of sub grain formation when tested in cathodically charged solution. On the other hand, long transgranular cracks were observed in the case of the alloy dominated with GP II zones, suggesting that the higher coherency of GP II zones promoted the formation of planar slip events. To correlate the effect of hydrogen on dislocation generation, dislocation densities were calculated using XRD peak broadening methodology. It suggested that the cathodic charging resulted in a 1.5 times higher dislocation density for the alloy with a higher volume fraction of GP II zones. Such a variation caused a higher drop in tensile strength for the case of the alloy having higher GP II zones in the cathodically charged condition.

使用阴极极化测试和慢应变速率测试研究了基体沉淀物-亚稳态MgZn ₂ ( ɳ ′) 和GP II 区域朝向环境辅助开裂(EAC)的电化学动力学。采用回归再时效处理 (RRA) 和改进的间断时效处理 (MA3) 分别产生高比例的ɳ ′ 和 GP II 区。较高的ɳ ' 分数导致合金上的析氢量增加三倍，从而降低了阴极充电和不充电的 3.5 wt% NaCl 溶液中的伸长率值。此外， ɳ的测量表面' 为主的合金在 3.5 wt% NaCl 溶液中显示出沿晶界的点蚀，并且在阴极充电溶液中进行测试时显示出大量的亚晶粒形成。另一方面，在以 GP II 区为主的合金中观察到长的穿晶裂纹，这表明 GP II 区较高的相干性促进了平面滑移事件的形成。为了关联氢对位错产生的影响，使用 XRD 峰展宽方法计算位错密度。这表明，对于具有较高 GP II 区体积分数的合金，阴极充电导致位错密度提高 1.5 倍。对于在阴极充电条件下具有较高GP II区的合金来说，这种变化导致拉伸强度的较大下降。