Preparation of Co-Ti-Fe-TM-Si-B Co-based Soft Magnetic Amorphous Alloys and Their Magnetic Properties

• Main Authors: Chia-Hao Yang, 楊佳豪
• Other Authors: Hsin-ming Wu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/45004532665761251330

碩士 === 大同大學 === 材料工程學系(所) === 97 === In this study, soft magnetic (Co0.75Ti0.25)85-XFeXTM5Si6B4 (X=0, 2, 4, 6, 8, 10 at％ and TM=Nb, Ni, or Mo) powders were prepared by mechanical alloying (MA) technique. It is aimed to investigate the effects of adding Nb、Ni, or Mo element to the Co-Ti-Si-B alloys and substituting Fe with different amounts of Co and Ti in the alloys on the glass forming ability of the alloys and their magnetic properties. The XRD results show that the (Co0.75Ti0.25)85-XFeXTM5Si6B4 (TM=Nb, Ni, Mo) powders, after milling for 15 hours, exhibit typical broad amorphous peaks. However, it is found in TEM selected area diffraction patterns of the same powders that there exist many fine crystalline diffraction spots superimposed on the halo amorphous rings, indicating that incomplete amorphous structures are obtained from these three alloy systems subjected to milling for 15 hours. Thermal analysis results show that glass transition temperatures can be determined in some (Co0.75Ti0.25)85-XFeXTM5Si6B4 alloys. The activation energies for crystallization were calculated for these three alloy systems by using Kissinger equation and found that the values are decreased with addition of Fe atoms. This implies that the substitution of Fe with Co and Ti cannot increase the thermal stability of the alloys. The magnetic measurements on the stress-relieved powders show that the intrinsic coercive forces are increased and the values of saturation magnetization are decreased, thereby decreasing the soft magnetic properties. It is concluded from this study that stress-relief treatment on the milled powders is not beneficial to the soft magnetic properties of incomplete amorphous alloys. This study still found some of the (Co0.75Ti0.25)85-XFeXTM5Si6B4 powders exhibit good soft magnetic properties.