Effects of Ce addition on microstructure and
mechanical properties of Mg-6Zn-1Mn alloy
mechanical properties of Mg-6Zn-1Mn alloy
(1. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China;
3. School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China)
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China;
3. School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China)
Abstract: 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 Mg12Ce 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 Mg12Ce 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.
Key words: Mg-6Zn-1Mn alloy; cerium; microstructure; mechanical properties