Transmission electron microscopy study of large field induced anisotropy (Co sub(1-) sub(x)e sub(x) sub(89)Zr sub(7)B sub(4) nanocomposite ribbons with dilute Fe-contents

• Published in: Journal of magnetism and magnetic materials Vol. 322; no. 3; pp. 315 - 321
• Main Authors: Ohodnicki, PR, Qin, Y L, McHenry, ME, Laughlin, DE, Keylin, V
• Format: Journal Article
• Language: English
• Published: 01.02.2010
• Subjects: Alloys; Anisotropy; Dilution; Electron microscopy; Face centered cubic lattice; Nanocrystals; Nanostructure; Phases
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2009.09.047

Electron microscopy was employed to investigate the structure of magnetic field crystallized (Co sub(1-) sub(x)e sub(x) sub(89)Zr sub(7)B sub(4) alloys with only dilute Fe-contents (x=0, 0.025, 0.05, and 0.10). The x=0.025 and 0.05 alloys exhibit very large field induced anisotropies and multiple nanocrystalline phases (BCC, FCC, and HCP) surrounded by an intergranular amorphous phase. Correlation between the volume fraction crystallized and the measured value of H sub(K) suggests that the large K sub(U) values are associated with the crystalline phases that form. Multiple crystalline phases are present for the highest K sub(U) alloys and so the presence of FCC and/or HCP-type nanocrystals may be responsible for these observations. High-resolution transmission electron microscopy (HRTEM) illustrates a number of microstructural features including (1) high densities of stacking faults in many of the FCC and, in particular, the HCP-type nanocrystals, (2) infrequent BCC/FCC orientation relationships, and (3) nanocrystals with disordered or long period stacking sequences of close-packed planes. High densities of planar faults are suggested as a potential source of K sub(U) for the FCC and HCP-type nanocrystals, but the origin of the large values of K sub(U) found in dilute Fe-containing, Co-rich "nanocomposite" alloys is an area where further work is needed.