M?ssbauer spectra study on phase variation in a high-coercivity FeCrCo alloy

Abstract

Variation of the coercivity induced by increasing Cr and Co contents and adding inpurities of Mo and Zr in FeCrCo alloys was investigated using Mssbauer spec tra, fransmission electron microscopy, x-ray diffraction, and magnetic measureme nt. A coercivity as high as 76kA/m is obtained, which is one and half times high er than that (40—52kA/m) of the common alloy. Mssbauer spectra shows that the microstructure of the high-coercivity alloy is apparently different from that of the traditional FeCrCo alloy. The alloy is single-phase after solution treat ment, the non-magnetic γ phase, which weakens the magnetic properties, does no t appear. During the thermomagnetic treatment, the atomic distribution is rearra nged, and leads to the formation of the α2 phase, the spinodal struc ture with the two-phase (α1 +α2 ) in the alloy fully forms after step-tempering. It might be beneficial for forming the high coercivity in alloy. Comparied with th e low-coercivity case, more of the α1 phase exist in the spinodal st ructure.