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MM: Fachverband Metall- und Materialphysik
MM 9: Liquid and Amorphous Metals - Brittle-to-ductile Transition
MM 9.5: Vortrag
Montag, 16. März 2020, 12:45–13:00, IFW D
Temperature and chemical bonding effects on the brittle-to-ductile transition in metal-metalloid glasses — Franco Moitzi1, •Daniel Şopu1,2, and Jürgen Eckert1,3 — 1Erich Schmid Institute of Materials Science, Leoben, Austria — 2Technische Universität Darmstadt, Darmstadt, Germany — 3Montanuniversität Leoben, Leoben, Austria
The relationship between the deformation behavior of metal-metalloid glasses and their intrinsic properties is studied using large-scale molecular dynamics simulations with hybrid interatomic potentials. Particularly, the influence of composition and temperature on the tensile deformation behavior of amorphous PdSi alloys is investigated. A transition from cracking perpendicular to the loading direction to shear banding can be achieved by increasing the temperature or decreasing the amount of silicon. A decrease in silicon content leads to fewer covalent bonds and, therefore, lower activation barriers for shear transformation zones and, consecutively, a high probability for shear band formation. On the other hand, at low temperatures these barrier cannot be overcome and cracking will dominate over shear banding. In this case, high activation barriers for local relaxation impedes stress redistribution into the glassy structure and, finally, cracking occurs. Additionally, the cracking path also depends on the degree of homogeneity. A corrugated fracture surface similar to experiment can be formed due to crack defection and cavitation ahead of the crack tip in chemically inhomogeneous samples. In contrast, a sharp cleavage-like fracture occurs for more homogeneous samples.