In the present chapter, results of our recent investigations on the role of gallium (Ga) on the aluminum (Al) site in Zr69.5Al7.5-xGaxCu12Ni11 metallic glass (MG) composition have been discussed. The material tailoring and cooling rate effects on the mechanical behavior of Zr-based metallic glasses and their nanocomposites have been studied. The substitution of Ga on the Al site in Zr–Al–Cu–Ni alloy affects the nucleation and growth characteristics of quasicrystals (QCs) and consequently changes the morphology of nanoquasicrystals. The Zr69.5Al7.5-xGaxCu12Ni11 system displayed metallic glass formation in the range of x = 0–7.5. In this process, we have come out with a new glass composition; Zr-Ga-Cu-Ni with glass transition temperature (Tg)—614 K. The effect of cooling rate on the glass forming ability (GFA) and mechanical properties for this new metallic glass composition has been discussed and compared with some other Zr-based metallic glasses. The various indentation parameters such as microhardness, yield strength, strain hardening constant, nature of shear band formation, and so on for the alloys have been analyzed. The study is focused on investigations of these materials to understand the structure (microstructure) property correlations.
Part of the book: Metallic Glasses
In this chapter, results of our recent investigations on the hydrogenation behavior of Zr-based quasicrystalline alloys and its effect on their structural and microhardness behavior have been discussed. The microstructural changes with respect to the addition of Ti and their correlation with hydrogen storage characteristics of (Zr69.5Al7.5Cu12 Ni11)100−xTix (x = 0, 4 and 12) quasicrystalline alloys have been studied. The substitution of Ti affects the nucleation and growth characteristics of nano-quasicrystals. The grain size of quasicrystals decreases with addition of Ti. The hydrogen uptake capacity of partially quasicrystalline alloys has been improved by the addition of Ti. The alloys with x = 0, 4, and 12 absorbed 1.20 wt.%, 1.38 wt.%, and 1.56 wt.% of hydrogen, respectively. A significant effect on the structure/microstructure and mechanical behavior of (Zr69.5Al7.5Cu12Ni11)100−xTix quasicrystalline alloys due to hydrogenation has been observed. The change in the microhardness behavior has been discussed based on microstructural variation resulting to Ti addition. The study is focused on investigations of these materials to understand the structure (microstructure)-property correlations.
Part of the book: New Advances in Hydrogenation Processes