Nanokristal Co70Si15B15 Toz Alaşımların Yapısal, Termal ve Manyetik Özelliklerinin İncelenmesi

Abstract

Bu çalışmada nanokristal Co₇₀Si₁₅B₁₅ (at.%) toz alaşımları, mekanik alaşımlama (MA) tekniği ile farklı öğütme sürelerinde üretilmiştir. Öğütme süresince alaşımların yapısal değişimleri, parçacık morfolojisi, termal kararlılıkları ve manyetik özellikleri incelenmiştir. X-ışını difraksiyonu (XRD) sonuçları, elementel tozların birbirleri ile olan reaksiyonu sonucu nanokristal Co(Si,B) katı çözelti fazını oluşturduğunu göstermiştir. Taramalı elektron mikroskobu (SEM) analizlerinden morfolojinin alaşımlama boyunca değiştiği ve parçacık boyutunun öğütmenin ilk safhalarında arttığı, daha sonra küçüldüğü anlaşılmıştır. Alaşımların yapısal durumuna bağlı olarak görülen ekzotermik reaksiyonun aktivasyon enerjisi 128 ± 3 kJ/mol olarak hesaplanmıştır. Manyetik sonuçlar, artan öğütme süresiyle hem doyum manyetizasyonunun (M_s) hem de koersivitenin (H_c) azaldığını göstermiştir.    

Keywords

• Mekanik alaşımlama,Co-Si-B alaşımı,Yapısal analiz,Termal kararlılık,Manyetik özellikler

Investigation of Structural, Thermal and Magnetic Properties of Nanocrystalline Co70Si15B15 Powder Alloys

Abstract

In this research, nanocrystalline Co₇₀Si₁₅B₁₅ (at.%) powder alloys were prepared by mechanical alloying (MA) technique at various milling times. Their structural changes, particles morphology, thermal stability and magnetic properties through the milling process were investigated. The X-ray diffraction (XRD) results showed that reaction of the elemental powders mixture resulted in the formation of the nanocrystalline Co(Si,B) solid solution phase. According to the scanning electron microscopy (SEM) analysis, particle morphology was changed during alloying and the particle size increased initially, then decreased. Depending on the structural state of the alloys, the apparent activation energy of the exothermic reaction was calculated as 128 ± 3 kJ/mol. Magnetic results indicated that both saturation magnetization (M_s) and coercivity (H_c) were decreased with increasing milling time.    

Keywords

• Mechanical alloying,Co-Si-B alloy,Structural analysis,Thermal stability,Magnetic properties

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