铸态和喷射成形态ZA35-3.5Mn合金在沸水中的腐蚀行为

Corrosion Behavior of Cast and Spray Formed ZA35-3.5Mn Alloys in Boiling Water

采用喷射成形技术和普通铸造方法制备了含3.5%Mn的ZA35合金,在沸水中研究两种形态合金的腐蚀行为。结果表明:喷射成形态合金腐蚀动力学曲线为抛物线型,其速率常数为2.14×10-3mg2.cm-4.s-1,腐蚀速率远远低于符合直线动力学规律的铸态合金;铸态合金腐蚀产物中含有MnO相,而喷射成形态合金的腐蚀产物中未出现MnO相;铸态合金中MnAl6多存在于晶界,η相和MnAl6为阴极,α相为阳极优先溶解;喷射成形态合金无MnAl6相析出,组织均匀细小,α相作为阳极溶解时,腐蚀产物Al(OH)3很容易在作为短路扩散的细小晶界上产物阻挡,阻止侵蚀性介质的进入,从而减缓腐蚀。

The ZA35-3.5Mn alloys were produced by means of spray forming technology and common casting method. Boiling water corrosion behavior of the alloys was studied. The results indicate that the corrosion dynamic curve of spray formed alloy was accordant with the parabolic curve with a rate parameter of 2. 14×10^-3 mg^2 · cm^-4 · s^-1, and the corrosion rate was remarkably slower than that of cast alloy whose curve was accordant with linear dynamics. MnO phase was found in the corroded product of cast alloy but not found in spray formed alloy. The MnA16 phase was at grain boundaries of the cast alloy, η phase and MnA16 were the cathodes, α-phase had the priority for anodic dissolution. Microstructure of the spray formed alloy was homogeneous and the grains were refined, MnA/6 phase was found. As the anode, the α-phase in spray formed alloy was dissolved, good anti- corrosion performance could be mainly attributed to the barrier effect of corroded product Al（OH）3 against the diffusion of corrosive media.