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Effect of copper on the thermal stability and non-isothermal crystallization behavior of Al 86 Ni 10-x Cu x RE 4 (x = 0.5–2.5) amorphous alloys prepared by melt spinning

Mansouri, M ; Sharif University of Technology | 2019

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  1. Type of Document: Article
  2. DOI: 10.1016/j.jnoncrysol.2018.11.027
  3. Publisher: Elsevier B.V , 2019
  4. Abstract:
  5. Microstructural features, thermal stability and crystallization kinetics of various melt spun Al-based alloys containing transition metals (TM = Ni, Cu) and Ce-based rare earth metals (MM: Misch Metal) were investigated via X-ray diffractometry (XRD), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). It is shown that the extended topological instability of Egami-Waseda model (λ criterion) is a useful tool to predict the crystallization behavior of the prepared alloys. FCC-Al nanoparticles are formed during the initial crystallization process. Calculation of the apparent activation energy using the Kissinger method indicates that partial replacement of nickel by copper decreases the thermal stability. The thermal stability in the presence of copper, however, can be improved by increasing the MM content. On the other hand, TEM studies determine that copper reduces the average size of FCC-Al nanocrystals from ~50 nm in Al 86 Ni 10 MM 4 to ~35 nm in Al 86 Ni 9 Cu 1 MM 4 amorphous alloy. Thermodynamic evaluation of the crystallization process and determination of the local crystallization index reveal that the primary crystallization in amorphous Al-based alloys containing MM, Ni and Cu is a complex diffusion controlled process
  6. Keywords:
  7. Activation energy ; Aluminum alloy ; Amorphization ; Primary crystallization ; Thermal stability ; Aluminum alloys ; Amorphous alloys ; Copper compounds ; Crystallization kinetics ; Differential scanning calorimetry ; High resolution transmission electron microscopy ; Melt spinning ; Microstructural evolution ; Microstructure ; Rare earths ; Scanning electron microscopy ; Stability ; Thermodynamic stability ; Topology ; Transition metal alloys ; Transition metals ; Transmission electron microscopy ; X ray diffraction analysis ; Apparent activation energy ; Crystallization behavior ; Crystallization process ; Microstructural features ; Nonisothermal crystallization ; Thermodynamic evaluation ; Topological instability ; Nanocrystalline alloys
  8. Source: Journal of Non-Crystalline Solids ; Volume 506 , 2019 , Pages 46-50 ; 00223093 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0022309318306835