均匀化处理对ZA35-0.3Zr合金组织及性能的影响

为了探索均匀化处理对ZA35-0.3Zr合金组织和性能的影响规律,通过组织分析、力学性能、电化学性能测试,确定了ZA35-0.3Zr合金均匀化处理的适宜温度和时间。结果表明,ZA35-0.3Zr合金枝晶偏析明显,晶界上Cu富集严重,存在非平衡β相。随着均匀化处理时间增加,ZA35-0.3Zr合金中CuZn5相逐渐消除,β相共析分解程度加大。对合金进行370℃×12h均匀化处理后,晶界处CuZn5相消除,枝晶偏析大大减少,同时非平衡β相基本消除,抗拉强度为306MPa,伸长率为7.35%。在3.5%的NaCl溶液中,开路电位与未均匀化处理合金相比变正,腐蚀电流密度减小了33.1%,耐腐蚀性增强。ZA35-0.3Zr合金适宜的均匀化处理工艺为370℃×12h。

Effects of Homogenizing Treatment on the Microstructure and Properties of ZA35-0.3Zr Alloy

Effects of homogenizing treatment on the microstructure and properties of ZA35-0.3Zr alloy were investigated by observing microstructure,testing mechanical properties and electrochemical behavior,and the optimized temperature and time of homogenizing treatment were presented.The results show that severe dendritic segregation and non-equilibrium β phases can be observed in as-cast structure of ZA35-0.3Zr alloy with severe Cu-enrichment on the grain boundary.With the increase of homogenizing treatment time,the CuZn5 phase is disappeared gradually,and eutectoid decomposition of β phase is increased.After homogenizing at 370 ℃ for 12 h,the CuZn5 phase disappears due to dissolving into the matrix to make dendrite segregation decrease significantly,and the absence of non-equilibrium β phase at grain boundaries can be observed.Meanwhile,tensile strength and elongation of the ZA35-0.3Zr alloy reach 306 MPa and 7.35%,respectively.The open circuit potential of homogenized ZA35-0.3Zr alloy is changed to positive,and the corrosion current density is reduced by 33.1%,compared with ZA35-0.3Zr alloy without homogenizing treatment in 3.5% NaCl solution,leading to the improvement of corrosion resistance of the alloy.The optimized homogenization treatment is 370 ℃×12 h.