Preparation and soft magnetic properties of Fe-P-B-Ge amorphous alloys

Amorphous Fe-based alleys were formed in Fe-80(P, B, Ge)(20) alloys by melt spinning. The temperature interval of the supercooled liquid region (Delta T-x) is defined by the difference between glass transition temperature (T- g) and crystallization temperature (T-x). The value of Delta T-x(= T-x-T-g) is 34 K for Fe80P10B6Ge4. The crystallization reaction takes place in a si ngle stage. The Delta T-x value increases by the dissolution of Al and/or G a, and the value is 43 K for Fe75Al5P10B6Ge4 and 49 K for Fe73Al5Ga2P10B6Ge 4. The effectiveness of additional Al and/or Ga elements with much larger a tomic sizes is interpreted to result from the formation of a higher degree of dense random packed structure. The crystallized structure consists of fo ur phases, alpha-Fe, Fe2B, Fe3B and Fe3P for Fe-(Al, Ga)-P-B-Ge amorphous a lloys. The long-range atomic rearrangement necessary for the nearly simulta neous precipitation of the four crystalline phases seems to cause the appea rance of the supercooled liquid region through the retardation of the preci pitation reaction. The Fe-based amorphous alloys exhibit soft magnetic prop erties of 1.09 to 1.27 T for saturation magnetization, 2.00 to 4.78 A/m for coercive force and 16000 to 24000 for permeability at 1 kHz. The synthesis of Fe-based amorphous alloys exhibiting soft magnetic properties and a wid e supercooled liquid region is important for the future development of a ne w type of soft magnetic material.