A systematic study of iron-based binary and multi-component alloys was undertaken to study the structural evolution in these powders as a function of milling time during mechanical alloying. Blended elemental powders of Fe100-XBX (where x = 5, 10, 17, 20, 22, 25, 37.5 and 50 at. %) and a bulk metallic glass (BMG) composition (Fe60Co8Zr10Mo5W2B15) were subjected to mechanical alloying in a SPEX 8000 mixer mill. X-ray diffraction technique was employed to study the phase evolution, crystallite size, lattice strain and also to determine the crystal structure(s) of the phases. Depending on the milling time, formation of supersaturated solid solutions, intermetallics, and amorphous phases was noted in the binary Fe-B powder mixtures. A maximum of about 22 at. % B was found to dissolve in Fe in the solid state, and formation of FeB and Fe2B intermetallics was noted in some of the powder blends. However, an interesting observation that was made, for the first time, related to the formation of a crystalline phase on continued milling of the amorphous powder in the BMG composition. This phenomenon, termed mechanical crystallization, has been explored. Reasons for the mechanical crystallization of the amorphous powder using the X-ray diffraction and electron microscopy methods have been discussed. External heat treatments of the milled powder were also conducted to study the complete crystallization behavior of the amorphous phase. Preliminary attempts were made to consolidate the milled BMG powder to bulk shape by hot isostatic pressing (HIP) and magnetic compaction techniques. Full densification was not achieved. Nanoindentation and microhardness tests were performed to characterize the mechanical properties of the glassy alloy. Nanoindentation results gave an elastic modulus of 59 GPa, lower than the expected value of 184 GPa; due to the presence of porosity in the consolidated sample. Optimization of the consolidation parameters is required to achieve a fully dense material.

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The aim of this study, which was carried out in two main parts, is to investigate the glass forming ability of Fe-based systems. The first part involves the theoretical modeling to cover the requirement of a predictive model to identify the Fe-based alloy families that have high glass forming ability in the frame of atomistic and thermodynamic approach. The second part involves the experimental investigations to prove the results of the conducted theoretical modeling studies. For this purpose, in the first part, theoretical investigations were performed to identify the third alloying elements that will lead to an increase in the glass forming ability on the base of electronic theory of alloys in pseudopotential approximation for selected Fe- based systems, Fe - (B, Zr, Nb, C, W). In the experimental part, in the frame of the theoretical investigation results, one of the theoretically modeled binary system, and the third alloying elements that were predicted to lead an increase in the glass forming ability of the selected binary system, were determined. As a first step, designated compositions were synthesized by using low grade conventional Fe-B alloy as a raw material by using centrifugal casting technique and copper mold casting method. To compare the results, same compositions were also cast from the high purity elements by using the same technique and method. For the characterization of these cast specimens, DSC, XRD, SEM, EDS and metallographic examination techniques were used. Amorphous structure was successfully obtained in the thin sections of the wedge-cast samples for Fe-B-Nb and Fe-B-W ternary systems.