Güç kaynakları ve otomotiv elektroniği uygulamaları için bor tabanlı kalın kesitli metalik cam / nanokristal manyetik malzemelerin geliştirilmesi

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2008
Akdeniz, Vedat M.
Mekhrabov, Amdulla O.
Aykol, Muratahan
This study is pertinent to setting a connection between glass forming ability (GFA) and topology of Fe-B based metallic glasses, identifying atomic effect order of elements increasing GFA and developing soft magnetic bulk metallic glasses (BMG) / bulk nanocrystalline alloys (BNCA) for industrial applications by combining intimate investigations on spatial atomic arrangements conducted via solid computer simulations with experimentations on high GFA bulk metallic glasses. In order to construct a theoretical framework, the nano-scale phase separation encountered in metallic glasses is investigated for amorphous Fe80B20 and Fe83B17 alloys via Monte Carlo and Reverse Monte Carlo simulations. All topological aspects revealed by developed analysis tools are compiled into a new model called Two-Dimensional Projection Model for predicting contributions to short and medium range order (MRO) and corresponding spacing relations. The outcome geometrically involves proportions approximating golden ratio. Soft magnetic Fe-Co-Nb-B-Si BMG and FeCo-Nb-B-Si-Cu BMG/BNCAs are produced with a totally conventional route, thermally characterized and their magnetic properties are measured. Influences of alloying elements that increase GFA and promote nanocristalization, on structural units and crystallization modes are identified by the developed model and radial distributions. While Co atoms substitute for Fe atoms, Nb and Si atoms deform trigonal prismatic units to provide local compactions at the outset of MRO. The GFA can be described by a new parameter quantifying the MRO compaction, cited as Φ. Moreover, after annealing Fe-Co-Nb-B-Si-Cu BMG alloy at 873 K for 300 s., the the precipitation is altered from Fe23B6 meta-sTablo phase to α-Fe nanocrystals, BNCAs are produced and this phenomenon is investigated structurally. It has been shown that developed Fe-B based BMGs and BNCAs show very good soft magnetic properties and optimum alloy composition is determined as (Fe36Co36B19.2Si4.8Nb4)99.25Cu0.75 with 3 mm thickness, 1.58 T saturation induction and 0.148 Oe coercivity.