Microstructural Characterization of Easy Glass Formers Fe-Nb-B-Y alloys.

Abstract

Fe-based bulk metallic glasses (BMG) have excellent physical and chemical properties such as high strength and corrosion resistance and is one of the most attractive advanced materials because of low cost of raw materials such as iron. Fe-based BMG chosen for this study are: Fe73Nb4B20Y3, Fe70Nb4B23Y3, Fe67Nb4B26Y3, Fe69-xNb4Si4B20+xY3 (x = 0, 3, 6), Fe43-xCo29Nb4Si4B20+x, Fe40-xCo29Nb4Si4B20+xY3 (at%). Ingots of the alloys will be produced through arc melting furnace and then will be submitted to different rapid solidification processing routes such as: melt-spinning and wedge copper mold casting with the aim of evaluate the glass forming ability (GFA) of alloys of Fe-Nb-B-Y system with additions of Co and Si. Both processing routes are promising techniques in order to obtain BMG with thickness in the millimeters range. The microstructure characterization of the Fe-based BMG alloys will be done trough X-ray diffraction (XRD), optical (OM) and scanning electron microscopy (SEM) together with the X-ray energy dispersive spectroscopy (EDS) and by differential scanning calorimetry (DSC). The GFA will be evaluated for the different products (melt-spun ribbon and wedge cast bulks) obtained for the Fe73Nb4B20Y3, Fe70Nb4B23Y3, Fe67Nb4B26Y3, Fe69-xNb4Si4B20+xY3 (x = 0, 3, 6), Fe43-xCo29Nb4Si4B20+x, Fe40-xCo29Nb4Si4B20+xY3 (at%) BMG alloys.Among the compositions selected for this system based in the results of the literature, it will be chosen the best chemical composition with the higher GFA and best properties. The results of GFA and properties will be compared with other Fe-based BMG studied by the group: Fe72Nb4Si10B14 and Fe43Co29Nb4Si5B19 (%at) and with the similar alloys presented in the literature. The aim is to evaluate the influence of the addition of different alloying elements in the properties of BMG.The objective of this project is the microstructure characterization of Fe-based BMG of Fe-Nb-B-Y system and with the additions of Co and Si to the best composition, since the preparation of the alloy in the arc melt furnace, metallographic analysis, thermal and microstructure characterization with the aim of obtaining Fe-based alloys with amorphous and/or metastable and the crystallization study of equilibrium phases of the best composition of the system.