| Title |
Research Paper - Transformations - : Spinodal Decomposition and Magnetic Properties of Sintered Alnico Magnets via Rapidly Solidified Powders |
| Authors |
최승덕(Seung Duck Choi); 양충진(Choong Jin Yang) |
| Abstract |
A new process for making Alnico type(Fe-Co-Ni-Al-Ti-Cu) permanent magnets was developed via the rapid solidifcation technology. The process includes extractive rapid solidifcation, pulverization and sintering. Magnetic properties of the Alnico type magnets were found to be subject to the shape and distribution(aspect ratio) of magnetically hard α₁ precipitates(Fe-Co rich). The higher the aspect ratio of the α₁ particles the better the magnetic properties were obtained. During heat treatment at a magnetic field(900∼600℃) an optimized aspect ratio of the α₁ particles was controllable for which parameters of the treatment are dependent upon the initial grain size of the rapidly solidified powders. The best magnetic properties of Alnico 8 type sintered magnets were obtained from the alloys containing 7.4 wt.%Ti heat treated isothermally at 820℃ for 15 minutes. The resulting properties were : H=2045 Oe, B_r = 7800 Gauss and (B.H)_(max) = 5.34 MGOe, respectively. |