| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 101 === Electromagnetic thermoablation is a new kind therapy for tumor. Soft magnetic bulk metallic glass is considered as a potential material for thermotherapy needle in electromagnetic thermoablation due to its high saturation magnetization (Ms), low coercivity (Hc) and high unusual eddy current loss. In this study Fe-B-Y-Nb alloys are selected as experimental materials of soft magnetic bulk metallic glass. The effect of Boron and Niobium content is investigated on the glass forming ability (GFA), magnetic property and heating ability in quaternary Fe-B-Y-Nb system.
Fe-B-Y-Nb metallic glass was formed by Arc Melting. It was a function of B content in Fe68.4B28-XY4.6Nb4 (X=0, 1, 2, 3, 4) and Nb content in Fe66.5+YB25Y4.5Nb4-Y (Y=0, 0.5, 1, 1.5) alloys. The glass forming ability and thermal property were studied by differential scanning calorimetry (DSC). The phase and microstructure were characterized by X-ray diffractometer (XRD) ,SEM-BE imgage and electron backscatter diffraction (EBSD), respectively. In addition, the magnetic property were measured by Vibrating Sample Magnetometer (VSM). The experiment for heating ability was all under the condition with 5cm distance away from coil which applied alterative magnetic field.
It is observed that Fe66.5B25Y4.5Nb4 alloy exhibits better GFA than other B content alloys with supercooled liquid region (Tx) 95. In Nb series alloys, Fe67B25Y4.5Nb3.5 alloy shows the best GFA in the study with Tx 97. According to hysteresis loop, Ms and Hc is 90.7 emu/g, 5.4 A/m for Fe66.5B25Y4.5Nb4 alloy, and 96.3 emu/g ,10.7 A/m for Fe67B25Y4.5Nb3.5 alloy. Owing to high Ms and low Hc, the heating ability can reach high temperature as Fe66.5B25Y4.5Nb4 alloy can reach 117oC and Fe67B25Y4.5Nb3.5 alloy can reach 132 oC.
In the B series alloys, less NbBFe causes high Ms and narrow Hc. Therefore, B25 alloy exhibites better heating ability. In the Nb series alloys, NbBFe is suppressed to enhance Ms, but Y2O3 grew to broaden Hc by reducing Nb content. Due to ebb and rise of soft magnetic property with precipitation, Fe67B25Y4.5Nb3.5 exhibited the greatest heating ability in the study.
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