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采用常规凝固技术在Mg_(94)Zn_3Y_xGd_(3-x)(x=3,2,1.5,1,摩尔分数)镁合金中获得具有长周期堆垛有序(LPSO)结构相,并对合金凝固组织、耐腐蚀性能和压缩力学性能进行系统研究。结果表明:n(Zn)/n(Y+Gd)=1:1的Mg_(94)Zn_3Y_xGd_(3-x)合金凝固组织含有α(Mg)相、Mg_3Zn_3R_E2(W)相、14H-LPSO相和少量颗粒状面心立方结构的Mg-Y-Gd相。Gd含量显著影响合金中LPSO相的形成和分布。随着Gd含量增加,合金中14H-LPSO相体积分数先增加后减少。结合电化学阻抗谱分析,LPSO增强Mg-Zn-Y-(Gd)镁合金在3.5%NaCl溶液中的电化学腐蚀等效电路为R(Q(R(QR)))。4种合金的腐蚀电流密度在10_(-5)A/cm2数量级。当x(Gd)≤1%时,Mg-Zn-Y-(Gd)合金表现出良好的耐蚀性,并优于工业用AZ91D镁合金。而当x(Gd)≥1.5%时,合金的耐腐蚀能力下降。在室温条件下,随着14H-LPSO相体积分数增加,Mg-Zn-Y-(Gd)合金的压缩力学性能显著提高。此外,适量W相和弥散分布块状Mg-Y-Gd相的钉扎作用有利于提高合金的力学性能。
A long period ordered ordered (LPSO) phase was obtained from Mg_ (94) Zn_3Y_xGd_ (3-x) (x = 3,2,1.5,1 mol fraction) magnesium alloy by conventional solidification technique. Tissue, corrosion resistance and compressive mechanical properties of a systematic study. The results show that the solidified microstructure of Mg 94 Zn 3 Y x Gd 3-x alloy with n (Zn) / n (Y + Gd) = 1: 1 contains α, Mg_3Zn_3R_E2 (W) phase and 14H-LPSO phase A Few Granular Face-centered Cubic Mg-Y-Gd Phases. Gd content significantly affects the formation and distribution of LPSO phase in the alloy. With the increase of Gd content, the volume fraction of 14H-LPSO phase in the alloy first increases and then decreases. According to the electrochemical impedance spectroscopy (EIS), the equivalent circuit of LPSO-enhanced electrochemical corrosion of Mg-Zn-Y- (Gd) magnesium alloy in 3.5% NaCl solution is R (Q (R (QR))). The corrosion current density of the four alloys is on the order of 10 (-5) A / cm2. The Mg-Zn-Y- (Gd) alloy shows good corrosion resistance when x (Gd) ≤1% and is superior to the industrial AZ91D magnesium alloy. When x (Gd) ≥1.5%, the corrosion resistance of the alloy decreases. At room temperature, the compressive mechanical properties of Mg-Zn-Y- (Gd) alloy significantly increase with the increase of the volume fraction of 14H-LPSO phase. In addition, the pinning effect of moderate W phase and dispersed Mg-Y-Gd bulk phase is helpful to improve the mechanical properties of the alloy.