定向凝固Zn-Al合金先共晶组织及电化学性能的研究

Effects of Magnetic Field on the Pre-eutectic Microstructure and Electrochemical Behavior of the Zn-Al Alloy

利用水平Bridgman定向凝固装置,在直流稳恒磁场下,对Zn-35Al-2.4Cu合金进行定向凝固试验。通过组织分析、二次枝晶臂间距测试、电化学性能测试,研究了磁场对Zn-Al合金先共晶组织和电化学性能的影响。结果表明,随着凝固速率增加,Zn-Al合金先共晶组织的二次枝晶臂间距逐渐减小,组织细化。在电流为80A、凝固速率为1K·s-1时,Zn-35Al-2.4Cu合金先共晶组织的二次枝晶臂间距最小,为24.294μm,在3.5%的NaCl溶液中腐蚀电流密度最小,为11.62μA/cm2,耐电化学腐蚀性能最优。

Zn-Al alloy was fabricated under a transverse direct current steady-state magnetic field by using horizontal Bridgman directional solidification equipment. Effects of magnetic field on the microstructure and electrochemical properties of Zn-Al alloy were investigated through structure analysis, second dendrite arm spacing （SDAS） measurement and electrochemical property testing. The results show that the SDAS is decreased gradually and the microstructure is refined with the increase of the solidification rate. The SDAS reaches up to the minimum value of 24. 294 μm, and corrosion current density is 11.62 μA/cm2 in 3.5% NaCl solution at the current intensity of 80 A and solidification rate of 1 K · s^-1.