| Summary: | 碩士 === 大同大學 === 材料工程學系(所) === 96 === This study prepared soft magnetic Fe72B20-XCXSi4Tm4 (Tm=Nb、Zr、Mo；X=0、2、4、6、8 at %) Fe-based powders by mechanical alloying technique. It investigated the effects of adding Nb, Zr, and Mo elements respectively to the Fe-B-Si-Tm Fe-based alloy and by substituting B with various amounts of C in the alloy on the forming ability of amorphous alloys and their magnetic properties. The XRD results indicate that the three Fe-B-C-Si-Tm (Tm=Nb、Zr、Mo) alloy systems, when subjected to mechanical milling for 30 h, can produce typical broad amorphous peaks. The thermal analysis results show that glass transition temperatures can be measured in some of the compositions in the Fe-B-C-Si-Tm (Tm=Nb、Zr、Mo) alloy systems. The activation energies for crystallization, calculated with Kissenger equation, for the three Fe-B-C-Si-Tm alloy systems increase relative to the Fe-B-Si-Tm alloy systems, indicating that the substitution of C with B can increase the forming ability of amorphous phase. The milled powders of various compositions were subjected to 500 ℃stress-relief treatment and show good thermal stability. The magnetic measurements on the stress-relieved powders show that their values of saturation magnetization are increased and the intrinsic coercive forces are decreased. This study found that some of the Fe-B-C-Si-Tm Fe-based powders exhibit good soft magnetic properties.
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