Quasi-static and dynamic compressive properties of Ti-based amorphous alloys modified from conventional Ti–6Al–4V alloy

Quasi-static and dynamic compressive properties of three Ti-based amorphous alloys modified from a conventional Ti–6Al–4V alloy were examined, and deformation mechanisms related with improvement of strength and ductility were investigated. The alloys contained 73–76 vol% of dendrites whose effective sizes ranged from 63 μm to 103 μm, and showed excellent compressive properties of the maximum strength over 1.7 GPa and the total strain over 18% under the quasi-static loading. Under dynamic compressive loading, the compressive strength increased up to 1.9 GPa, whereas the total strain decreased to 4–6%. In the alloy containing considerably large dendrites, the dynamic deformation was mainly concentrated on a maximum shear stress plane, and only a few deformation bands were observed beneath the fracture surface. In the alloy having sufficiently small effective dendrites for developing deformation bands, deformation bands and shear bands were initiated simultaneously at dendrites and the amorphous matrix, respectively, as the applied stress could be effectively dispersed. These findings provided the optimum effective dendrite size (63 μm) for improving compressive properties by understanding the quasi-static and dynamic compressive deformation behavior.