Crystallization behavior of sub-surface in (Zr,Cu)95Al5 bulk metallic glass induced by different counter-face materials

Abstract

The crystallization behaviors of sub-surface in (Zr,Cu)95Al5 bulk metallic glass (BMG) induced by different counter-face materials have been investigated. The results indicated that the different crystalline phases were distributed throughout the sub-surfaces of BMG pins after sliding. As sliding against alumina, the formed nanocrystallites, which were mainly composed of Al3Zr4 and Al2O3, were independent of strengthening the sub-surface of BMG pin. As against zirconia, however, the nanocrystallites, which were mainly composed of (Zr,Cu) phase with a smaller size, changed the deformation mechanism from the traditional dislocation-mediated to the deformation controlled by grain boundaries, which reinforced the sub-surface of worn surface. Therefore, the harder zirconia disk was severely scratched and a large amount ZrO2 powder was transferred to the worn surface of BMG pin. It was elucidated that the crystallization layers and its role in the tribological behaviors various were strongly influenced by the counter-faces.