Fatigue and Fracture Behavior of a Ca-Based Bulk-Metallic Glass

Abstract

The compression and fatigue behavior of a Ca 65 Mg 15 Zn 20 bulk-metallic glass (BMG) was studied in air at room temperature. During the preparation of cubical samples of the Ca 65 Mg 15 Zn 20 for compression and fatigue investigations, small spherical cavities were found. Under both monotonic and cyclic compression loadings of the samples, fractures initiated at these cavities and propagated in a direction generally parallel to the loading axis. Finite-element analysis (FEA) was used to model the fracture behavior. The FEA of a centrally located spherical void showed that under compression loading, large tensile stresses evolved in the cavities. The orientation of the maximum principal stress (P1) was found to be normal to the direction of crack propagation, which is consistent with the experimental finding. Stresses in deeply embedded adjacent voids and those in superficial voids were also studied. The influence of the void location in the cubical sample on the fracture behavior was quantitatively discussed.

Modeling crack growth from pores under compressive loading with application to metallic glasses

“…1), where a typical microcrack was seen to initiate and propagate a short distance. The preferential sites for crack-nucleation and the initial direction of the crack propagation were in good agreement with the numerical results yielded by finite-element analyses [13]. Moreover, the fracture surface also exhibited a dominant splittingfracture mode.…”

Understanding the Fracture Behaviors of Metallic Glasses—An Overview

“…Although the fracture behaviors of most BMGs are controlled by the shear band deformation mechanism, there are exceptions, of course. In some Fe-based, Ca-based, Mg-based, Rare earth-based and other brittle MGs, the fracture mode under compression/tension loading can change from shear mode (fracture along the shear band path, which is~45 • from the loading axis) to cleavage mode (fracture along the plane perpendicular to the applied stress), split mode [45] (fracture along the plane parallel to the applied stress) or fragmentation mode. The cleavage or split surface of these brittle MGs can be divided into mirror, mist, and hackle regions [41,46].…”

“…(fracture along the plane perpendicular to the applied stress), split mode [45] (fracture along the plane parallel to the applied stress) or fragmentation mode. The cleavage or split surface of these brittle MGs can be divided into mirror, mist, and hackle regions [41,46].…”