Investigation of Martensitic Phase Transformation and Magnetic Properties of Fe-30%Ni-2.6wt%Mo-X%Co Alloys

Öz

In this study, the microstructure of thermal effective martensitic phase transformation observed in the Fe-30wt.%Ni-2.6wt.%Mo-Xwt.%Co (X = 0.8, 1.8) alloy was investigated morphologically and crystallographically by using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In SEM studies, it was observed that the morphology of the martensite phase changed from lath and lenticular structure to massive structure with the addition of Co to the alloy. In addition to this, nano martensite formation was also observed as another effect of Co addition (figure 2c, d). Properties of lenticular martensite, electron diffraction pattern of austenite and martensite structures were given by TEM studies. According to the Differential Scanning Calorimetry (DSC) analysis, it was determined that the martensitic transformation temperature (Ms) significantly increased with the increase of the Co amount in the alloys. Also, by using Mössbauer spectroscopy, it was shown that the amount of martensite increased with the increase of Co amount and the magnetic order of the alloy changed accordingly.

Anahtar Kelimeler

• Thermally induced martensite
• Crystallographic properties
• Magnetic properties
• TEM
• SEM
• Mössbauer spectroscopy

Fe-30%Ni-%2.6Mo-X%Co Alaşımlarının Martensitik Faz Dönüşümünün ve Manyetik Özelliklerinin Araştırılması

Öz

Bu çalışmada, Fe-30%Ni-2.6%Mo-X%Co (X = 0.8, 1.8 ) alaşımında gözlenen termal etkili martensitik faz dönüşümünün mikro yapısı, taramalı elektron mikroskobu (SEM) ve geçirmeli elektron mikroskobu (TEM) kullanılarak morfolojik ve kristalografik olarak incelenmiştir. SEM çalışmalarında, alaşıma Co eklenmesiyle martensit fazın morfolojisinin iğnemsi ve merceksi yapıdan masif yapıya dönüştüğü gözlenmiştir. Bununla birlikte Co ilavesinin diğer bir etkisi olarak nano martensit oluşumu da görülmüştür (figure 2c, d). Lentiküler martensitin özellikleri, östenit ve martensit yapılarının elektron kırınım modeli TEM incelemeleri ile verilmiştir. Diferansiyel Taramalı Kalorimetre (DSC) analizlerine göre, alaşımlardaki Co miktarının artmasıyla martensitik dönüşüm sıcaklığının (Ms) önemli ölçüde arttığı belirlenmiştir. Ayrıca Mössbauer spektroskopisi kullanılarak Co miktarının artmasıyla martensit miktarının arttığı ve alaşımın manyetik düzeninin buna bağlı olarak değiştiği gösterilmiştir

Anahtar Kelimeler

• Termal etkili martensit
• Kristalografik özellikler
• Manyetik özellikler
• TEM
• SEM
• Mössbauer Spektroskopisi

Kaynakça

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