Effects of Annealing on Enthalpy Recovery and Nanomechanical Behaviors of a La-Based Bulk Metallic Glass

• Main Authors: Ting Shi, Lanping Huang, Song Li
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Metals
• Subjects: bulk metallic glasses; structure relaxation; enthalpy recovery; nanoindentation; annealing
• Online Access: https://www.mdpi.com/2075-4701/11/4/579

Structural relaxation and nanomechanical behaviors of La₆₅Al₁₄Ni₅Co₅Cu_9.2Ag_1.8 bulk metallic glass (BMG) with a low glass transition temperature during annealing have been investigated by calorimetry and nanoindentation measurement. The enthalpy release of this metallic glass is deduced by annealing near glass transition. When annealed below glass transition temperature for 5 min, the recovered enthalpy increases with annealing temperature and reaches the maximum value at 403 K. After annealed in supercooled liquid region, the recovered enthalpy obviously decreases. For a given annealing at 393 K, the relaxation behaviors of La-based BMG can be well described by the Kohlrausch-Williams-Watts (KWW) function. The hardness, Young’s modulus, and serrated flow are sensitive to structural relaxation of this metallic glass, which can be well explained by the theory of solid-like region and liquid-like region. The decrease of ductility and the enhancement of homogeneity can be ascribed to the transformation from liquid-like region into solid-like region and the reduction of the shear transition zone (STZ).