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Titanium-based Bulk Metallic Glasses : Glass Forming Ability and Mechanical Behavior

Abstract : Two Ti-based bulk metallic glasses, with the nominal composition of Ti40Zr25Ni8Cu9Be18 and Ti41.5Cu37.5Ni7.5Zr2.5Hf5Sn5Si1, who exhibit different structural nature (quenched-in nuclei/amorphous structure and phase separation-like structure, respectively), were investigated. Our studies focus on thermally induced structural transformations (structural relaxation and crystallization) behavior and their effects on thermodynamics and kinetics of the subsequent glass transition and crystallization as well as room-temperature mechanical response in addition to homogeneous deformation in the supercooled liquid region and low-temperature physical properties. As a result, their enthalpy relaxation both follows the general characteristics although their unique structure nature. The latter shows better thermal stability however lower glass forming ability than the former. Phase transformation upon heating was investigated by Neutron diffraction, and JMA as well as Starink model was introduced to study their crystallization kinetics. They both exhibit high value of compressive strength, however with significantly different plastic strain at room temperature. Their unique deformation and fracture behavior whose fracture angles change from<45 to 90° can be interpreted by ellipse criterion. Structural relaxation and crystallization lead to a drastic degradation of plasticity, although the structural relaxation may produce a slight increase in hardness as well as fracture strength. The latter exhibits a good superplasticity and workability, and a beneficial domain for optimum hot workability of this alloy has been located by constructing the power dissipation efficiency map.
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Submitted on : Sunday, September 5, 2010 - 11:40:41 PM
Last modification on : Friday, December 18, 2020 - 1:08:04 PM
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Jinna Mei. Titanium-based Bulk Metallic Glasses : Glass Forming Ability and Mechanical Behavior. Mechanics [physics.med-ph]. Université Joseph-Fourier - Grenoble I, 2009. English. ⟨tel-00515163⟩

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