Polymorphic microstructure of a MnCu damping alloy solidified under magnetic field

Strong magnetic field has been extensively used to modify the solidification microstructure. This paper reports a polymorphic characteristic of microstructure of Mn–Cu based damping alloy during solidification under different magnetic fields, which was characterized by using optical microscopy, scanning electron microscopy and x-ray diffraction. The results show that the secondary dendrite arm spacing as well as the grain size decreases with the increase of magnetic field intensity. Large amounts of nanoscale precipitates with a relatively higher Mn content have formed at both the Mn-rich dendrite and the Cu-rich spacings during aging treatment. XRD discloses that all the γ phase diffraction peaks have increased after aging and the lattice distortion nonlinearly increases with the increase of magnetic fields. (paper)