(1. 中南大学 材料科学与工程学院，长沙 410083；
2. Department of Chemical and Materials Engineering, University of Auckland, Auckland 1102, New Zealand)
摘 要: 利用两种等通道角挤压(ECAP)方法(普通单步ECAP和两步ECAP)制备细晶ZK60合金。采用金相显微镜、扫描电镜、透射电镜和X射线衍射仪对合金的组织和织构进行观察，通过拉伸试验研究不同ECAP方法对合金力学性能的影响。结果表明：与单步ECAP变形相比，两步ECAP变形，由于降低了变形温度，晶粒细化效果更好；经过(240 ℃，4道次)+(180 ℃，4道次)两步ECAP变形后，合金晶粒细化至约0.8 μm；合金的力学性能与材料的织构密切相关，由于存在织构软化效应，与挤压态相比，经单步ECAP变形后合金的强度有所降低，而伸长率明显提高；但经两步ECAP变形后，由于细晶强化和亚结构强化的作用，合金的强度得到提高。
关键字: ZK60 镁合金；等通道角挤压； 显微组织；力学性能；动态回复；再结晶；织构
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
(2. Department of Chemical and Materials Engineering, University of Auckland, Auckland 1102, New Zealand）
Abstract:Ultra-fine grain ZK60 magnesium alloys were fabricated separately by conventional single-step equal channel angular pressing (ECAP) processing and two-step ECAP processing. The microstructures and mechanical properties of the ZK60 magnesium alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and tensile test, and the texture was measured by XRD. The results show that, two-step ECAP is more effective in grain refinement than single-step ECAP process due to the lower deformation temperature. The grain size is refined to 0.8 μm after being processed with treatment of (240 ℃, 4 passes)+(180 ℃, 4 passes). Compared with the as-received ZK60 alloy, the single-step ECAP processed alloy has lower strength but higher elongation to failure. The decrease in strength is mainly ascribed to texture softening. However, after two-step ECAP process, the strength is improved due to the enhancement of fine grain strengthening and substructure strengthening.
Key words: ZK60 magnesium alloy; equal channel angular pressing; microstructure; mechanical properties; dynamic recovery; recrystallization; texture
