Advanced characterization of Al–Ni-Sm amorphous alloys with dispersion of round Pb-rich nanoparticles

The development of materials with special microstructures is a continuing theme of research due to their improved physical and mechanical properties. Rapid solidification can lead to amorphous or partially crystalline microstructures, depending on the imposed processing conditions and compositions allowing the production of composite materials. Al-Ni-Sm alloys can be easily obtained in the amorphous state by rapid solidification processing so that composites could be generated depending on the cooling conditions. In this work, new results are shown for Al-based amorphous matrix composites produced during rapid solidification of Al83.5Ni10Sm6.5, Al81.5Ni10Sm6.5Pb2 and Al83.5Ni8Sm6.5Pb2 (atom percent) alloys. Lead (Pb) was added to the amorphous forming composition alloy due to its immiscibility with the main alloying elements. Ribbon samples were obtained by melt spinning technique. Besides the use of ordinary characterization techniques, such as X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), advanced transmission electron microscopy (TEM) was employed to reveal the special microstructure features forming these alloys. A strong influence of the Pb addition on crystallization behavior has been identified. Also, the size and morphology of the nanocrystalline Pb-rich minority phase within the amorphous matrix is examined. These effects were explained based on the immiscibility of Pb with the alloy components.