摘要
通过SEM观察及采用EPMA测定和失重法,对3.5%NaCl水溶液中金属型铸造和触变成型镁合金AZ91D腐蚀行为及腐蚀后微观组织特征进行分析,表明触变成形镁合金的腐蚀速率小于金属型铸造合金的腐蚀速率,原因是微观组织的差异导致其耐蚀性不同;镁合金腐蚀电偶对是以α相和共晶α相作为阳极,β相作为阴极,阳极是被腐蚀相,腐蚀是分阶段分层次进行的,α相是腐蚀初期的被腐蚀相,共晶α相是后期被腐蚀的主要相,β相和共晶α相的相对位置和结构决定着后期腐蚀速率;触变成型中β相的偏析提高了合金的耐蚀性。
The corrosion behaviors and microstructure characteristic both as-cast and thixoformed AZ91D magnesium alloy in 3.5%NaCl aqueous solution were studied by SEM and electro-probe microanalyses （EDMA） and weight loss method. The results show that the corrosion rate ofthixoformed AZ91D magnesium alloy is lower than that of as-cast AZ91D magnesium alloy because of the different microstructure; The corroding electric-doublet of the alloy takes α phase and eutectic α phase as anode and β phase as cathode in galvanic corrosion ,and the anode is corroded.Corrosion process takes place in sequence, the α phase was corroded at initiation of corrosion ,the eutectic α phase at late stage, the corrosion rate at late stage is decided by the relations of position and strcture between β phase and eutectic α phase.The segregation ofβ phase improves the corrosion resistance ofthixoformed AZ91D.
出处
《热加工工艺》
CSCD
北大核心
2007年第12期22-25,共4页
Hot Working Technology
基金
中国-新西兰政府间国际科技合作项目(2002DFG00020)
863领域重点国际合作项目(2002AADF3303)
关键词
镁合金
微观组织
腐蚀
magnesium alloy
microstructure
corrosion
