Effects of Heat Treatment on Microstructure and Magnetic Properties of (Fe_0.52Co_0.30Ni_0.18)₇₃Cr₁₇Zr₁₀ Amorphous Alloy

Abstract

(Fe0.52Co0.30Ni0.18)73Cr17Zr10 amorphous ribbons were prepared by melt-spun method and annealed at different temperatures. X-ray diffraction, atomic force microscopy and vibrating sample magnetometer were adopted to study the effect of annealing temperature on the microstructure and magnetic properties of this alloy.The results show that the crystallization process of this alloy is amorphous→α-Fe(Co)+amorphous'→α-Fe(Co)+Cr2Ni3+Fe3Ni2+Cr2Zr+ unidentified phase. When annealing temperature Ti is lower than Tg, the Ms increases slightly as a result of relaxation of the internal stress of the as-quenched amorphous alloy. When Ti is in between Tx and Tp1, the Ms significantly increases due to the partial crystallization of amorphous precursors to create a homogeneous distribution of α-Fe(Co) nanocrystals within a residual amorphous matrix. When Ti is higher than Tp1, the Ms drops rapidly, which may be caused by the grain growth and the formation of paramagnetic phase. This alloy after annealed at 565℃ has the best magnetic property(Ms=106.8A·m2·kg-1). The results of AFM observation show that in the annealed amorphous ribbons the grain size measured from AFM graphs is much larger than that of the α-Fe(Co) nanocrystal size caculated by Scherrer method, which is a typical phenomenon of coated grain.

Keywords

• Fe-based amorphous alloy
• heat treatment
• microstructure
• magnetic property