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    Investigation on the transport and magnetism properties of the boron-substituted NiMnSb
    (Springer, 2023) Kilic, Gokhan; Abboosh, Omar; Kirat, Gokhan; Aksan, Mehmet Ali; Aydogdu, Ayse; Aydogdu, Yildirim
    We fabricated Ni46Mn41Sb13-xBx (x = 0, 1, 2, 3 and 4) (at.%) Heusler alloys using arc melting method and studied the electronic and magnetic properties of the alloys. It was seen that the martensite transformation temperatures shifted to higher temperatures with increasing the B-content in the system. It was found that for x less than 2, the alloys were in the austenite phase at the room temperature. However, when x is larger than 2, the crystal structure changed and a transformation to a martensite phase has occurred at room temperature. There were significant changes in lattice constants by boron substitution, which influenced the electrical and magnetic properties of the alloys. These changes are mainly related to the different atomic radius of Sb and B, which changed the atomic arrangement along a-axis. Hysteresis observed between the heating and cooling M-T curves obviously showed a field-induced martensitic transformation (FIMT) in the alloys. While the characteristic magnetization behavior of NiMnSb system was obtained at high magnetic fields, unstable magnetic behavior was observed at low magnetic fields. The boron substitution caused decrease in magnitude of the saturation magnetization (M-sat).
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    Thermal Properties, Microstructure and Microhardness of Cu-Al-Co Shape Memory Alloy System
    (Springer India, 2014) Aydogdu, Yildirim; Kurum, Ferdi; Kok, Mediha; Yakinci, Zehra Deniz; Aydogdu, Ayse
    In this study, the effects of Co content on the crystal structure, transformation temperatures and microstructure of Cu-Al-Co shape memory alloy system were investigated. It was found that Cu-Al-Co alloy system has also 18R type martensitic structure, which is commonly observed in copper-based systems. The transformation temperatures were found to be higher than 250 A degrees C and they do not show a linear increase or decrease with Co content. The microstructural examination revealed the presence of martensite phase and precipitates. It was realized that the size of precipitate increases with increasing Co content. It can be stated that the hardness increased with increasing Co content. All these results point out that increasing Co content increases the strength of Cu-Al-Co shape memory alloy system.