Hacimli metal camların üretimi ve manyetik özellikleri ile camlaşma yeteneğinin yapay sinir ağları kullanılarak modellenmesi
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Date
2010-07-15
Authors
Kabaer, Mehmet
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Publisher
Uludağ Üniversitesi
Abstract
Bu çalışmada manyetik hacimli metal camların yapısal, termal ve manyetik özellikleri incelendi. Kimyasal kompozisyonu Fe36Co36B19.2Si4.8X4 (X=Nb, Mo0.5W0.5) olan alaşımlar santrifüj döküm yöntemi kullanılarak üretildi. Bu işlem ile alaşımların hızlı katılaştırılması sağlandı. Üretilen Fe36Co36B19.2Si4.8Nb4 ve Fe36Co36B19.2Si4.8Mo2W2 alaşımlarının kritik kalınlıkları (tmax) sırası ile 2 mm ve 1.5 mm olarak belirlendi.Malzemelerin yapısal analizleri X-ışını kırınımı (XRD) tekniği ile yapıldı. Üretilen hacimli metal camların XRD spektrumlarından elde edilen sonuçlara göre, Fe36Co36B19.2Si4.8Nb4 alaşımı tam amorf yapıda, Fe36Co36B19.2Si4.8Mo2W2 alaşımı ise parçalı amorf yapıda olduğu görüldü. Fe36Co36B19.2Si4.8Mo2W2 alaşımının amorf yapıya sahip olma eğilimi araştırılmak üzere bu alaşım eriyik eğirme yöntemi kullanılarak şerit haline getirildi. Yapılan XRD analizi ile elde edilen şeridin 25 µm kalınlıkta amorf yapıya sahip olduğu anlaşıldı. Malzemelerin termal analizleri diferansiyel taramalı kalorimetre (DSC) tekniği ile yapıldı. Fe36Co36B19.2Si4.8Nb4 alaşımı için cam geçiş sıcaklığı (Tg) 817 K ve kristalleşme sıcaklığı (Tx) ise 856 K olarak ölçüldü. Aynı alaşım için aşırı soğutulmuş bölge (?Tx) 39 K olarak hesaplandı. Fe36Co36B19.2Si4.8Mo2W2 alaşımı içinse Tx 799 K olarak ölçülse de, 1.5 mm kalınlık için belirgin bir cam geçiş sıcaklığı gözlenemedi. Alaşımların manyetik analizleri için titreşken örnek manyetometresi (VSM) kullanıldı. Ölçüm sonuçlarında alaşıma Nb yerine Mo ve W konulduğunda doyum mıknatıslanmasının (Ms) 1.02 T'dan 1.25 T'ya, sıfırlayıcı alanın (Hc) da 19 A/m'den 1685 A/m'ye çıktığı görüldü.Son olarak da hacimli metal camların camlaşma yeteneğini ve manyetik özelliklerini modellemek için yapay sinir ağları kullanıldı. Manyetik hacimli metal camların camlaşma yeteneğini ve manyetik özelliklerini belirlemek için literatürde daha önceden yayınlanan alaşımların termal ve manyetik özellikleri kullanıldı. Geliştirilen yapay sinir ağlarının öğrenme işlemi genetik algoritma ile gerçekleştirdi. Ağın çıkışında elde edilen manyetik ve camlaşma yeteneğini belirleyen özellikler deneysel veriler ile iyi bir uyum içerisinde olduğu görüldü. Dolayısıyla geliştirilen modeller, hacimli metal camların termal ve manyetik özelliklerinin tahmininde kullanılabilir.
In this study the structural, thermal and magnetic properties of magnetic bulk metallic glasses were investigated. Alloys having Fe36Co36B19.2Si4.8X4 (X=Nb, Mo0.5W0.5) chemical composition were fabricated by using centrifugal casting method. This process is based on rapid solidification. The critical thicknesses for fabricated Fe36Co36B19.2Si4.8Nb4 and Fe36Co36B19.2Si4.8Mo2W2 alloys were 2 mm and 1.5 mm, respectively. The structural characterizations of materials were studied using X-ray Diffraction (XRD). According to the XRD results of the fabricated alloys, it was seen that alloy Fe36Co36B19.2Si4.8Nb4’s structure was totally amorphous and alloy Fe36Co36B19.2Si4.8Mo2W2’s structure was partially amorphous. To investigate the tendency of Fe36Co36B19.2Si4.8Mo2W2 alloy on having the amorphous structure, this alloy was fabricated as a ribbon by using melt spinning method. With the results of the XRD analysis, it was seen that fabricated ribbon had amorphous structure with 25 µm thickness. The thermal characterizations of materials were measured by the differential scanning calorimetry (DSC) technique. It was measured for the alloy Fe36Co36B19.2Si4.8Nb4, glass transition temperature (Tg) as 817 K and crystallization temperature (Tx) as 856 K. For the same alloy, super cooled region (ΔTx) was calculated as 39 K. Although the crystallization temperature for Fe36Co36B19.2Si4.8Mo2W2 alloy was measured as 799 K, no observable distinct glass transition was seen for the same alloy. The magnetic characterizations of samples were measured by the vibrating sample magnetometer (VSM) technique. It was seen from the results that, if we substitute Nb for Mo and W, the saturation magnetization was increased from 1.02 T to 1.25 T and also coercivity was increased from 19 A/m to 1685 A/m. Finally, the artificial neural network was used to model the glass forming ability and magnetic properties of magnetic bulk metallic glasses. Previously reported data in the literature was used to calculate the glass forming ability and magnetic properties of magnetic bulk metallic glasses. The developed network has been trained by genetic algorithm. The neural network has been successfully applied for the prediction of the glass forming ability and magnetic parameters of bulk glassy alloys and the results are found to be in a very good agreement with the experimental data. So the developed network model can be used for the prediction of glass forming ability and magnetic parameters of bulk metallic glasses.
In this study the structural, thermal and magnetic properties of magnetic bulk metallic glasses were investigated. Alloys having Fe36Co36B19.2Si4.8X4 (X=Nb, Mo0.5W0.5) chemical composition were fabricated by using centrifugal casting method. This process is based on rapid solidification. The critical thicknesses for fabricated Fe36Co36B19.2Si4.8Nb4 and Fe36Co36B19.2Si4.8Mo2W2 alloys were 2 mm and 1.5 mm, respectively. The structural characterizations of materials were studied using X-ray Diffraction (XRD). According to the XRD results of the fabricated alloys, it was seen that alloy Fe36Co36B19.2Si4.8Nb4’s structure was totally amorphous and alloy Fe36Co36B19.2Si4.8Mo2W2’s structure was partially amorphous. To investigate the tendency of Fe36Co36B19.2Si4.8Mo2W2 alloy on having the amorphous structure, this alloy was fabricated as a ribbon by using melt spinning method. With the results of the XRD analysis, it was seen that fabricated ribbon had amorphous structure with 25 µm thickness. The thermal characterizations of materials were measured by the differential scanning calorimetry (DSC) technique. It was measured for the alloy Fe36Co36B19.2Si4.8Nb4, glass transition temperature (Tg) as 817 K and crystallization temperature (Tx) as 856 K. For the same alloy, super cooled region (ΔTx) was calculated as 39 K. Although the crystallization temperature for Fe36Co36B19.2Si4.8Mo2W2 alloy was measured as 799 K, no observable distinct glass transition was seen for the same alloy. The magnetic characterizations of samples were measured by the vibrating sample magnetometer (VSM) technique. It was seen from the results that, if we substitute Nb for Mo and W, the saturation magnetization was increased from 1.02 T to 1.25 T and also coercivity was increased from 19 A/m to 1685 A/m. Finally, the artificial neural network was used to model the glass forming ability and magnetic properties of magnetic bulk metallic glasses. Previously reported data in the literature was used to calculate the glass forming ability and magnetic properties of magnetic bulk metallic glasses. The developed network has been trained by genetic algorithm. The neural network has been successfully applied for the prediction of the glass forming ability and magnetic parameters of bulk glassy alloys and the results are found to be in a very good agreement with the experimental data. So the developed network model can be used for the prediction of glass forming ability and magnetic parameters of bulk metallic glasses.
Description
Keywords
Manyetik amorf alaşımlar, Hacimli metal camları, Camlaşma yeteneği, Yapay sinir ağı, Magnetic amorphous alloys, Bulk metallic glasses, Glass forming ability, Neural network
Citation
Kabaer, M. (2010). Hacimli metal camların üretimi ve manyetik özellikleri ile camlaşma yeteneğinin yapay sinir ağları kullanılarak modellenmesi. Yayınlanmamış yüksek lisans tezi. Uludağ Üniversitesi Fen Bilimleri Enstitüsü.