Effect of Inoculation on Phase Formation and Indentation Hardness Behaviour of Zr<SUB>47.5</SUB>Cu<SUB>45.5</SUB>Al<SUB>5</SUB>Co<SUB>2</SUB> and Zr<SUB>65</SUB>Cu<SUB>15</SUB>Al<SUB>10</SUB>Ni<SUB>10</SUB> Bulk Metallic Glass Matrix Composites

Abstract

Bulk metallic glass matrix composites have emerged as a new potential material for structural engineering applications owing to their superior strength, hardness and high elastic strain limit. However, their behaviour is dubious. They manifest brittleness and inferior ductility which limit their applications. Various methods have been proposed to overcome this problem. Out of these, introduction of foreign particles (inoculants) during solidification has been proposed as the most effective. In this study, an effort has been made to delimit this drawback. A systematic tale has been presented which explains the evolution of microstructure in Zr 47.5 Cu 45.5 Al 5 Co 2 and Zr 65 Cu 15 Al 10 Ni 10 bulk metallic glass matrix composites with varying percentage of ZrC inoculant as analysed by secondary electron, back scatter electron imaging of "as cast" unetched samples and indentation microhardness testing. Secondary electron imaging of indents was also performed which shows development of shear transformation zones at edges of square of indents. Mostly, no cracking was observed, few cracks bearing Palmqvist morphology were witnessed in samples containing lower percentage of inoculant. A support is provided to hypothesis that inoculations remain successful in promoting phase formation and crystallinity and improving toughness.