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Author: Pauly, S. × Subject: Mechanical properties ×

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    Glass-forming ability, phase formation and mechanical properties of glass-forming Cu-Hf-Zr alloys
    (Amsterdam : Elsevier B.V., 2019) Kosiba, K.; Song, K.; Kühn, U.; Wang, G.; Pauly, S.
    The influence of Hf additions on the glass-forming ability (GFA), phase formation and mechanical properties of Cu50HfxZr50-x (x = 2,5,10,20 at.%) alloys has been systematically investigated. We report on a distinct correlation between phase formation and GFA of Cu50Zr50-based alloys. Increasing additions of Hf reduce the thermal stability of the high-temperature B2 Cu(Hf,Zr) phase, while the thermal stability of the corresponding undercooled melt is enhanced. The GFA of these alloy series gradually raises up to 10 at.% Hf, whereas at 20 at.%Hf, the GFA is drastically lowered, since the B2 Cu(Hf,Zr) phase becomes unstable and the precipitation of the low-temperature equilibrium phases is favoured. This interrelation determines the microstructure and results in the formation of Cu-Hf-Zr-based bulk metallic glass composites. These composites not only show appreciable macroscopic plastic strain, but also high yield strength.
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    A tensile deformation model for in-situ dendrite/metallic glass matrix composites
    (London : Nature Publishing Group, 2013) Qiao, J.W.; Zhang, T.; Yang, F.Q.; Liaw, P.K.; Pauly, S.; Xu, B.S.
    In-situ dendrite/metallic glass matrix composites (MGMCs) with a composition of Ti46Zr20V12Cu5Be17 exhibit ultimate tensile strength of 1510 MPa and fracture strain of about 7.6%. A tensile deformation model is established, based on the five-stage classification: (1) elastic-elastic, (2) elastic-plastic, (3) plastic-plastic (yield platform), (4) plastic-plastic (work hardening), and (5) plastic-plastic (softening) stages, analogous to the tensile behavior of common carbon steels. The constitutive relations strongly elucidate the tensile deformation mechanism. In parallel, the simulation results by a finite-element method (FEM) are in good agreement with the experimental findings and theoretical calculations. The present study gives a mathematical model to clarify the work-hardening behavior of dendrites and softening of the amorphous matrix. Furthermore, the model can be employed to simulate the tensile behavior of in-situ dendrite/MGMCs.