Bulk Metallic Glasses II Overview

JOM

, Volume 62, Issue 4, pp 10-18

The fracture toughness of bulk metallic glasses

  • Jian XuAffiliated withShenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences Email author 
  • , Upadrasta RamamurtyAffiliated withDepartment of Materials Engineering, Indian Institute of Science
  • , Evan MaAffiliated withDepartment of Materials Science and Engineering, The Johns Hopkins University

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Abstract

Stiffness, strength, and toughness are the three primary attributes of a material, in terms of its mechanical properties. Bulk metallic glasses (BMGs) are known to exhibit elastic moduli at a fraction lower than crystalline alloys and have extraordinary strength. However, the reported values of fracture toughness of BMGs are highly variable; some BMGs such as the Zr-based ones have toughness values that are comparable to some high strength steels and titanium alloys, whereas there are also BMGs that are almost as brittle as silicate glasses. Invariably, monolithic BMGs exhibit no or low crack growth resistance and tend to become brittle upon structural relaxation. Despite its critical importance for the use of BMGs as structural materials, the fracture toughness of BMGs is relatively poorly understood. In this paper, we review the available literature to summarize the current understanding of the mechanics and micromechanisms of BMG toughness and highlight the needs for future research in this important area.