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- ItemIn-situ tensile testing of ZrCu-based metallic glass composites(London : Nature Publishing Group, 2018) Sun, H.C.; Ning, Z.L.; Wang, G.; Liang, W.Z.; Pauly, S.; Huang, Y.J.; Guo, S.; Xue, X.; Sun, J.F.ZrCu-based bulk metallic glass composites (BMGCs) are well known for their plastic deformability, superior to traditional metallic glasses (MGs), which is attributed to a unique dual-phases structure, namely, the glassy matrix and unstable B2 phase. In the present study, in-situ tensile testing is used to trace the deformation process of a ZrCu-based BMGC. Three deformation stages of the BMGC, i.e., the elastic-elastic stage, the elastic-plastic stage, and the plastic-plastic stage are identified. In the elastic-elastic and elastic-plastic stages, the yield strength and elastic limit are major influenced by the volume fraction of the B2 crystals. In the plastic-plastic stage, the B2 phase stimulates the formation of multiple shear bands and deflects the direction of shear bands by disturbing the stress field in front of the crack tip. The deformation-induced martensitic transformation of the metastable B2 phase contributes to the plasticity and work hardening of the composite. This study highlights the formation and propagation of multiple shear bands and reveals the interactions of shear bands with structural heterogeneities in situ. Especially, the blocking of shear bands by crystals and the martensitic transformation of the B2 phase are critical for the mechanistic deformation process and illustrate the function of the B2 phase in the present BMGCs.
- ItemPhase formation of a biocompatible Ti-based alloy under kinetic constraints studied via in-situ high-energy X-ray diffraction(Amsterdam : Elsevier B.V., 2020) Kosiba, K.; Rothkirch, A.; Han, J.; Deng, L.; Escher, B.; Wang, G.; Kühn, U.; Bednarcik, J.The biocompatible Ti40Cu34Pd14Zr10Sn2 bulk metallic glass was rapidly heated, also known as flash-annealed, at varying heating rates up to 1579 K/s. Thereby, the phase formation was characterized via advanced in-situ high-energy X-ray diffraction. It has been found that the evolving kinetic constraints can be used as a tool to deliberately alter the crystalline phase formation. This novel processing route permits to select phases to crystallize to a predefined fraction and, thus, to potentially design the microstructure of materials according to a specified property-profile. Consequently, flash-annealing poses a unique synthesis route to design materials with, for instance, good biomechanical compatibility.