固溶处理对Mg-2.0Zn-0.4Mn-xAl合金微观组织和性能的影响

Effect of solution treatment on microstructure and properties of Mg-2.0Zn-0.4Mn-xAl alloys

通过光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)和万能材料试验机等研究了固溶处理对Mg-2.0Zn-0.4Mn-xAl合金微观组织和性能的影响,借助质量损失实验和电化学实验研究了合金在3.5%NaCl溶液中的耐腐蚀性能。结果表明:合金中第二相的数量及尺寸随着Al含量的增加而增加,第二相组成由纳米级棒状MgZn_(2)相和椭圆状Mg_(2)(Zn,Al)_(11)相(0~4 mass%Al)向Mg_(17)Al_(12)相(6 mass%Al)转变。当Al含量为4.0 mass%时,合金具有较好的综合力学性能和耐蚀性能,其极限抗拉强度、屈服强度及伸长率分别为(180.1±3.1)MPa、(124.7±2.8)MPa和(16.7±1.5)%,在3.5%NaCl溶液中浸泡72 h后,合金的静态腐蚀速率和析氢腐蚀速率分别为(0.822±0.056)mm/y和(0.790±0.045)mm/y。

Effect of solution treatment on microstructure and properties of Mg-2.0Zn-0.4Mn-xAl alloy was studied by means of optical microscope(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and universal material testing machine,and the corrosion resistance of the alloy in 3.5%NaCl solution was studied by static mass loss experiment and electrochemical test.The results show that the number and size of the second phase in the alloy increase with the increase of Al content,and the composition of the second phase changes from the nanoscale rod-like MgZn_(2)phase and elliptic Mg_(2)(Zn,Al)_(11)phase(0-4 mass%Al)to Mg_(17)Al_(12)phase(6 mass%Al).When the content of Al is 4.0 mass%,the alloy has good comprehensive mechanical properties and corrosion resistance,and its ultimate tensile strength,yield strength and elongation are(180.1±3.1)MPa,(124.7±2.8)MPa and(16.7±1.5)%,respectively.After immersion in 3.5%NaCl solution for 72 h,the average static corrosion rate and the hydrogen evolution corrosion rate of the alloy are(0.822±0.056)mm/y and(0.790±0.045)mm/y,respectively.