Yield criteria and strain-rate behavior of Zr57.4Cu16.4Ni8.2Ta8Al10 metallic-glass-matrix composites
We have examined the yielding and fracture behavior of Zr57.4Cu16.4Ni8.2Ta8Al10 metallic-glass-matrix composites with a small volume fraction (similar to 4 pct) of ductile crystalline particles under quasi-static uniaxial tension and compression and dynamic uniaxial compression. The yield stress of the composite is the same for quasi-static tension and compression, consistent with a von Mises yield criterion. The measured average angle between the shear bands and the loading axis in quasistatic compression is 47 +/- 2 deg, significantly larger than the value of similar to 42 deg typically reported for single-phase metallic glasses. Finite element modeling (FEM) shows that the measured value is consistent with both the von Mises criterion (48 +/- 4 deg) and the Mohr-Coulomb criterion (46 +/- 5 deg). The fracture surface angles, however, are 41 +/- 1 deg (compression) and 54 +/- 2 deg (tension), in good agreement with observations of single-phase metallic glasses. At low strain rates (< 10(-1) s(-1)), the yield stress is independent of strain rate, while at higher strain rates (> 10(0) s(-1)), the failure stress decreases with increasing strain rate, which again is similar to the behavior of single-phase glasses. These results indicate that while the presence of the particles has a significant effect on the yield behavior of the composites, the fracture behavior is largely governed by the properties and behavior of the amorphous matrix.
Record created on 2007-11-14, modified on 2016-08-08