Journal of Materials Research


Reciprocating wear mechanisms in a Zr-based bulk metallic glass

H.W. Jina1, R. Ayera1, J.Y. Kooa1, R. Raghavana2 and U. Ramamurtya2 c1

a1 Advanced Structural Materials Section, ExxonMobil Research & Engineering Company, Annandale, New Jersey 08801

a2 Department of Materials Engineering, Indian Institute of Science, Bangalore-560012, India


The dry sliding friction coefficient μ and the wear volume loss W, in a zirconium-based bulk metallic glass (BMG) under high-frequency (50 Hz) reciprocating conditions, were investigated with the objective of assessing the influence of free volume and crystallization on the wear behavior of amorphous metals. The BMG samples were annealed either below the glass transition temperature Tg to induce structural relaxation and hence reduce the free volume that controls plasticity through shear-band formation or above Tg to crystallize the amorphous BMG prior to wear testing. Results show that the wear behavior of both the as-cast and relaxed glasses was dominated by the oxidation of the surface layers. A sharp transition in the contact electrical resistance complemented by a marked increase in μ was noted. This was attributed to the formation of a thick tribo film with high oxygen concentration and its subsequent delamination. The μ values, before as well as after the transition, in the relaxed glasses were similar to those for the as-cast alloy. However, a gradual decrease in W with annealing temperature was observed. A good correlation between W and nanohardness was noted, implying that the intrinsic hardness in the BMGs controlled the wear rate.

(Received July 20 2006)

(Accepted October 12 2006)

Key Words:

  • Amorphous;
  • Hardness;
  • Oxidation


c1 Address all correspondence to this author. e-mail: