Nanoindentation characteristics of Zr69.5Al7.5 − xGaxCu12Ni11 glasses and their nanocomposites

This work deals with the indentation behavior of Zr69.5Al7.5 − xGaxCu12Ni11 (x = 0, 1.5, 7.5 at.%) alloys. A comparison between their nanohardness and reduced elastic modulus values of the as-synthesized glassy phase with their nanocomposites has been made. The indentation characteristics of a novel Ga substituted glass composition corresponding to x = 7.5 have shown significant improvement in regard to hardness and elastic modulus. The evidence of pile up has been observed in case of as-synthesized glassy ribbons. The load (P) versus depth (h) curves for as-synthesized melt–spun ribbons displayed the presence of displacement burst, which are known as pop-ins. The amount of energy per unit volume required for the shear band formation in glassy state has been estimated based on the pop-ins observed in P–h curve. This seems to decrease with Ga addition. Based on transmission electron microscopic observations of indented glassy specimen, the possibility of nanocrystallization has been ruled out.

• The nanoindentation characteristics of Ga substituted Zr–Al–Cu–Ni metallic glass composition on Al site has not been studied so far. Apart from this, we are reporting the indentation characteristics of Zr–Ga–Cu–Ni metallic glass that has been discovered by us recently.
• This work makes detailed investigations on the nanoindentation characteristics of the glass as well as their glass-nanocomposites. The issue of nanocrystallization during indentation has been addressed and delineated based on TEM investigation