The microstructure and thermal stability of the two‐phase amorphous melt‐spun alloys ejected from a double‐chamber crucible

• Published in: Journal of microscopy (Oxford) 2023-05, Vol.290 (2), p.117-124
• Main Authors: Ziewiec, Krzysztof, Jankowska‐Sumara, Irena, Ziewiec, Aneta
• Format: Article
• Language: English
• Subjects: Alloys; Crucibles; Differential scanning calorimetry; Electron microscopy; Fractures; Liquids; metallic glasses; Microstructure; Phase composition; Scanning electron microscopy; Tensile tests; Thermal stability; Transmission electron microscopy
• ISSN: 0022-2720; 1365-2818
• DOI: 10.1111/jmi.13181

This work presents the microstructure and properties of two‐phase amorphous melt‐spun alloys ejected from the crucible with partition between liquids. The microstructure was studied by scanning electron microscopy and transmission electron microscopy and the phase composition was studied by X‐ray diffraction. The thermal stability of the alloys was determined using differential scanning calorimetry. The microstructure study proves that the composite alloys are heterogeneous because of the existence of the two amorphous phases obtained due to the use of a partition between the liquids. This microstructure correlates with complex thermal characteristics not found in homogeneous alloys of the same nominal composition. The layered structure of these composites influences the formation of fractures during tensile tests. LAY DESCRIPTION The aim of this investigation is to present the special features and properties of the glassy two‐component melt‐spun alloys in comparison to the melt‐spun alloys ejected from single‐chamber crucible. The studies of the composite microstructure were performed using transmission electron microscopy and scanning electron microscopy. The alloys also were heated to elevated temperatures and their characteristics were studied by means of differential scanning calorimetry. The phase composition of the alloys was investigated using X‐ray diffraction. The results of the microstructure examination show that these alloys are heterogeneous due to the production method. The special feature of the alloys is that they essentially inherit the transformations possible to occur in the precursor alloys after amorphisation of the these precursors. Results of thermal analysis also confirm the occurrence of transformations of the regions from the transition zones of the intermediate compositions between the two main constituents A and B. These transformations are found to be similar to the transformations identified in the amorphous alloys of the averaged compositions, that is, the homogeneous chemical compositions that are possible for obtaining, when alloys A and B are molten together to form a single liquid phase before ejection into a spinning cylinder. Unique feature of these composite alloys is lamellar morphology. This microstructure consists mainly of the stripes/layers of precursor alloys A and B that are inserted into each chamber of the two‐chamber crucibles. After ejection of the alloys into the surface of the spinning cooper wheel, they