Temperature evolution in the deformation of bulk metallic glasses

Embargo until
Date
2014-05-02
Journal Title
Journal ISSN
Volume Title
Publisher
Johns Hopkins University
Abstract
To determine the extent of heating in the deformation of bulk metallic glasses, a fusible tin coating method was used to detect shear band heating in amorphous Zr57Ti5Cu20Ni8Al10 loaded under quasi-static uniaxial compression. A negative tone photolithography process was used to pattern tin lines 15 µm wide with 5 µm spacing on the metallic glass specimens. Quasi-static compression tests at a constant strain rate were performed using a high-stiffness, low-bending testing machine. Some samples were allowed to fracture while others were arrested before fracture. High-rate load data was acquired with a piezoelectric load cell and allowed for a precise determination of the time scale associated with the shearing events as well as final fracture. For samples where loading was halted prior to fracture there was no observed evidence of melted tin despite large shear offsets. For the samples loaded to fracture, there was evidence of melted tin near the fracture surface. These observations were attributed to the characteristic time scale of these events, measured from the load data. Temperature rise calculations were performed for both cases and it was found that the shear banding events with a time t ≈ 6 ms resulted in a ΔT < 1 K while the fracture event with a time t ≈ 30 µs resulted in ΔT ≈ 2900 K. These calculations and results are consistent with other similar studies leading to the conclusion that there is no significant temperature rise in the normal deformation of bulk metallic glasses.
Description
Keywords
bulk metallic glasses, shear banding
Citation