固溶时效处理Mg-Zn-Al-Sn-Mn合金的微观组织演变及腐蚀行为研究
Investigation on corrosion behaviors of Mg-Zn-Al-Sn-Mn alloy treated by solution and artificial aging
唐建伟 1陈良 2鲍意浩 2李志刚 2阙标华2
作者信息
- 1. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials of Ministry of Education,Shandong University,Ji'nan 250061,China;Department of Mechanical Engineering,Kyushu University,Fukuoka 819-0395,Japan
- 2. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials of Ministry of Education,Shandong University,Ji'nan 250061,China
- 折叠
摘要
通过电子背散射衍射、扫描电子显微术、透射电子显微术、电化学试验和浸泡试验,研究了Mg-Zn-Al-Sn-Mn合金热挤压、固溶和人工时效过程中的微观组织演变和腐蚀行为.研究发现,挤压型材表现出由变形晶粒和再结晶晶粒组成的多峰结构特点.固溶处理后,大部分第二相颗粒在固溶过程中溶解进镁基体中,合金中形成了完全再结晶的晶粒结构,且晶粒尺寸显著增大.上述两方面使得固溶处理后的合金表现出最佳的耐腐蚀性能.时效处理24 h后,合金硬度达到峰值水平(HV 84),其强化效果主要来源于密集分布的τ-Mg32(Al,Zn)49析出相.随着时效时间的延长,过时效状态下析出相尺寸出现典型的双峰分布.然而,时效处理过程中析出的大量τ-Mg32(Al,Zn)49颗粒导致了合金耐腐蚀性能的降低.此外,腐蚀机制也由点蚀和丝状腐蚀转变为晶间腐蚀.
Abstract
Hot extrusion,solution,and artificial aging were conducted on the designed Mg-Zn-Al-Sn-Mn alloy.The microstructure evolution and corrosion behaviors of the alloy were studied.A multimodal structure composing of both deformed and recrystallized grains is observed in as-extruded alloy,while a fully recrystallized grain structure forms in solutionized alloy.Moreover,the majority of second phases dissolved into Mg matrix during solution.In aged state,the highest hardness of HV84 was realized after 24 h aging,and the densely distributed τ-Mg32(Al,Zn)49 was the main strengthening precipitates.With increasing aging time,some amounts of precipitate had evidently coarsened by the dissolution of smaller ones,leading to a bimodal distribution of large(150-200 nm)and fine(～50 nm)precipitates in over-aging state.The solutionized alloy owned the optimal corrosion resistance because of its large grain size and dissolution of second phase.However,the corrosion resistance was degraded again by aging treatment attributed to a mass of τ-Mg32(Al,Zn)49.Moreover,the intergranular corrosion took the place of pitting and filiform corrosion,and became a dominant corrosion mechanism in aged alloy.
关键词
镁合金/固溶处理/时效处理/微观组织/耐腐蚀性能Key words
Mg alloy/solution treatment/aging/microstructure/corrosion resistance引用本文复制引用
基金项目
国家自然科学基金(52222510)
山东省重点研发计划(2021ZLGX01)
出版年
2023
NETL
NSTL
万方数据