CAJ | 학술논문

利用光学显微镜、X射线衍射、扫描电镜和差热分析等手段研究添加Ce对Mg-6Zn-1Mn镁合金在不同状态下的微观组织和相组成的影响,并对合金的室温力学性能进行测试和比较.结果表明:添加的Ce元素以Mg12aCe相存在于合金中,主要分布在晶界和枝晶间,铸态晶粒得到细化;添加Ce元素能够明显地提高挤压态Mg-6Zn-1Mn合金的屈服强度和伸长率,这是由于热挤压过程中弥散分布在晶界上的Mg12aCe相能够有效钉扎晶界,抑制再结晶晶粒长大,从而得到更加细小的热变形晶粒组织;然而,添加Ce元素恶化了时效态Mg-6Zn-1Mn合金的力学性能,这是因为热处理不能使这些Mg12aCe相固溶于基体中,在拉伸断裂时Mg12aCe相表面形成微裂纹,导致力学性能下降.
이용광학현미경、X사선연사、소묘전경화차열분석등수단연구첨가Ce대Mg-6Zn-1Mn미합금재불동상태하적미관조직화상조성적영향,병대합금적실온역학성능진행측시화비교.결과표명:첨가적Ce원소이Mg12aCe상존재우합금중,주요분포재정계화지정간,주태정립득도세화;첨가Ce원소능구명현지제고제압태Mg-6Zn-1Mn합금적굴복강도화신장솔,저시유우열제압과정중미산분포재정계상적Mg12aCe상능구유효정찰정계,억제재결정정립장대,종이득도경가세소적열변형정립조직;연이,첨가Ce원소악화료시효태Mg-6Zn-1Mn합금적역학성능,저시인위열처리불능사저사Mg12aCe상고용우기체중,재랍신단렬시Mg12aCe상표면형성미렬문,도치역학성능하강.
The effects of Ce addition on the microstructure of Mg-6Zn-1Mn alloy during casting, homogenization, hot extrusion, T4, T6 and T4+two-step aging were investigated. The mechanical properties of alloys with and without Ce were compared. The results showed that Ce had an obvious effect on the microstructure of ZM61-0.5Ce alloy by restricting the occurrence of dynamic recrystallization and restraining the grain growth during extrusion and heat treatment subsequently. A new binary phase Mg12aCe was identified in ZM61-0.5Ce alloy, which distributed at grain boundaries and was broken to small particles distributed at grain boundaries along extrusion direction during extrusion. The mechanical properties of as-extruded ZM61-0.5Ce alloy were improved with the addition of Ce. The improved tensile properties of as-extruded ZM61-0.5Ce alloy were due to the finer grain sizes as compared to ZM61 alloy. However, the UTS and YS decreased severely and the elongation increased when ZM61-0.5Ce was treated by T6 and T4+two-step aging. Brittle Mgl2Ce phase, which was distributed at the grain boundary areas and cannot dissolve into the Mg matrix after solution treatment, became crack source under tensile stress.