Glass-Forming Ability and Corrosion Resistance of Al88Y8-xFe4+x (x = 0, 1, 2 at.%) Alloys

Structural characterization of newly-developed Al79Ni5Fe5Y11 and Al79Ni11Fe5Y5 alloys with amorphous matrixes

The low glass-forming ability of aluminium-based metallic glasses significantly limits their development and preparation. This paper updates the current state of knowledge by presenting the results of structural studies of two newly-developed Al79Ni5Fe5Y11 and Al79Ni11Fe5Y5 alloys with a reduced aluminium content (< 80 at.%). The alloys were produced by conventional casting (ingots) and melt-spinning (ribbons). Structural characterization was carried out for bulk ingots first, and then for the melt-spun ribbons. The ingots possessed a multiphase crystalline structure, as confirmed by X-ray diffraction and scanning electron microscopy observations. The amorphous structure of the melt-spun ribbons was determined by X-ray diffraction and transmission electron microscopy. SEM observations and EDX element maps of the cross-section of melt-spun ribbons indicated a homogeneous elemental composition. Neutron diffraction revealed the presence of nanocrystals in the amorphous matrix of the melt-spun ribbons. DSC data of the melt-spun ribbons showed exothermic events corresponding to the first crystallization at temperatures of 408 °C and 387 °C for Al79Ni5Fe5Y11 and Al79Ni11Fe5Y5, respectively.

Effect of Pre-Oxidation Treatment on Corrosion Resistance of FeCoSiBPC Amorphous Alloy

In this paper, the corrosion resistance of FeCoSiBPC amorphous alloy after pre-oxidation and non-oxidation heat treatment is investigated. The corrosion behaviors of Fe₈₀Co₃Si₃B₁₀P₁C₃ amorphous alloys in 1 mol/L NaCl solution were investigated by the electrochemical workstation. The pre-oxidation heat treatment can improve the corrosion resistance of FeCoSiBPC amorphous alloy through an increase in the Ecorr value from −0.736 to −0.668 V, which makes it easy to reach a passive state. The corroded morphology and products of amorphous alloys were tested by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM/TEM analysis showed that, after pre-oxidation treatment, the oxide layer was divided into two layers: the inner layer was amorphous, the outer layer appeared crystalline, and the main oxide was Fe₂O₃. During the oxidation process, Co and P elements diffused from the inner layer to the outer layer, forming phosphorus and cobalt oxides with high corrosion resistance on the surface of the ribbon, thereby improving the corrosion resistance of the ribbon.

Study of crystallization mechanism of Al-based amorphous alloys by in-situ high temperature X-ray diffraction method

The role of transition metals (TMs) addition on the formation and crystallization of amorphous Al₈₅TMs₁₀Y₅ alloys was described using in-situ high-temperature X-ray diffraction. The structural results were compared with differential scanning calorimetry and dynamical mechanical analysis to obtain detailed information about the nucleation and growth of crystalline phases. The performed analysis confirmed that Fe and Cu addition drastically changes the crystallization temperature and the phase composition of the fully crystallized alloys. While for Al₈₅Ni₁₀Y₅ alloy, the second crystallization step is related to the formation of Al₁₉Ni₅Y₃ phase, for Al₈₅(Ni, Fe)₁₀Y₅ and Al₈₅(Ni, Fe, Cu)₁₀Y₅ alloys crystallization of Al₁₅Fe₉Y₂ phase was observed. Interestingly, the performed analysis showed that forming a homogenous amorphous phase is not necessary to obtain the best corrosion resistance. It was noted that the precipitation of the YCr₂Al₂₀ phase in the Cu-rich amorphous matrix should be a much more interesting approach.

Structure and Magnetic Properties of Fe-B-La-Al Alloy

Nanocrystalline magnetic materials are of great interest in order to meet the needs of electronics and electrical engineering. There are many possibilities to modify the synthesis parameters and chemical composition in order to obtain the most desirable magnetic properties and microstructure. The paper discusses an iron-based alloy with the addition of boron lanthanum and aluminium. The alloy was obtained by induction melting and casting with a melt-spinner. The main purpose of the work was to analyze the structure and properties of both the starting alloys in the form of ingots and the obtained tapes. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration magnetometry (VSM) and microhardness measurements using the Vickers method were carried out.

Effect of Transition Elements on the Thermal Stability of Glassy Alloys 82Al-16Fe-2TM (TM: Ti, Ni, Cu) Prepared by Mechanical Alloying

In the present study, the thermal stability and crystallization behavior of mechanical alloyed metallic glassy Al₈₂Fe₁₆Ti₂, Al₈₂Fe₁₆Ni₂, and Al₈₂Fe₁₆Cu₂ were investigated. The microstructure of the milled powders was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The results showed remarkable distinction in thermal stability of the alloys by varying only two atomic percentages of transition elements. Among them, Al₈₂Fe₁₆Ti₂ alloy shows the highest thermal stability compared to the others. In the crystallization process, exothermal peaks corresponding to precipitation of fcc-Al and intermetallic phases from amorphous matrix were observed.