Effect of Ce-rich mish metals and electromagnetic stirring on microstructure of AZ91D magnesium alloy
(1.College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China2.南京航空航天大学 材料科学与技术学院，南京 210016)
Abstract: The influence of Ce-rich mish metal（MM） and electromagnetic stirring（EMS） on microstructure evolution of AZ91D magnesium alloy was investigated by optical microscopy, scanning electron microscopy（SEM）, energy dispersion spectrum（EDS） and X-ray diffraction（XRD）. The microstructure of AZ91D and alloying AZ91D is different. Except dominant primary α（Mg） and β-Mg 17Al 12 in AZ91D, a new phase Al 11MM3 is observed in alloyed AZ91D. Increasing Ce-rich MM, primary α grains can be refined, the content and grain size of β obviously decrease, furthermore, its morphology degrades from discontinuous network to separated particles, and Al 11MM3 amount substantially increases and acicular Al 11MM3 aggregates into clusters at grain boundaries. In EMS process, α morphology evolves from rosette to sphere, and then spherical-like with the decrease of isothermal stirring temperature. Moreover, Al 11MM3 mainly distributes inside primary grains and eutecticum in form of short-rod. EMS can alter not only the primary morphology but Al 11MM3.
Key words: electromagnetic stirring； Ce-rich mish metals； AZ91D； non-dendritic microstructure； isothermal stirring