Nanoindentation characteristics of Zr69.5Al 7.5 - XGaxCu12Ni11 glasses and their nanocomposites

Abstract

This work deals with the indentation behavior of Zr69.5Al 7.5 - 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. © 2011 Elsevier B.V. All rights reserved.