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Synthesis and characterization of zirconium based bulk amorphous alloys

2004
Saltoğlu, İlkay
In recent years, bulk amorphous alloys and nanocrystalline materials have been synthesized in a number of ferrous and non-ferrous based alloys systems, which have gained some applications due to their unique physico-chemical and mechanical properties. In the last decade, Zr-based alloys with a wide supercooled liquid region and excellent glass forming ability have been discovered. These systems have promising application fields due to their mechanical properties; high tensile strength, high fracture toughness, high corrosion resistance and good machinability. In this study, the aim is to model, synthesize and characterize the Zr-based bulk amorphous alloys. Initially, theoretical study on the basis of the semi-empirical rules well known in literature and the electronic theory of alloys in pseudopotential approximation has been provided in order to predict the potential impurity elements that would lead to an increase in the GFA of the selected Zr-Ni, Zr-Fe, Zr-Co and Zr-Al based binary systems. Furthermore, thermodynamic and structural parameters were calculated for mentioned binary and their ternary systems. According to the theoretical study, Zr67Ni33 binary system was selected and its multicomponent alloys were formed by adding its potential impurity elements; Mo, W and Al. Centrifugal casting method was used to produce alloy systems. Structural characterizations were performed by DSC, XRD, SEM and EDS methods. In the near-surface regions of Zr60Ni25Mo10W5 and Zr50Ni20Al15Mo10W5 alloys, amorphous structure has been observed. Experimental studies have shown that Zr-Ni based systems with impurity elements Mo, W and Al, not widely used in literature, might be good candidates for obtaining high GFA.