Deformation behaviour of Zr-based metallic glass and metallic glass composite at elevated temperatures

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In this project, the detailed nanocrytallization of the Zr55Cu30Ni5Al10 monolithic bulk metallic glass will be investigated using TEM in comparison with that of the partially nanocrystallized Zr55Cu30Ni5Al10 bulk metallic glass obtained by previous annealing after the deformation of both types of samples at high strain rates and at elevated temperatures. The comparison of the different types of samples allows to understand the effect of the nanocrystallization on the high temperature deformation behaviour and the transitionfrom inhomogeneous to homogeneous flow regarding the reaction between the newly nanocrystallized phase and the partially nanocrystallized phase obtained by previous annealing. In addition, it is of interest to optimize the casting conditions of the Zr66.4Cu10.5Ni8.7Al8 bulk metallic glass composite with ductile dendrites in order to control and establish a different lenght scale and volume fraction of dendrites, and hence to understand the effect of the morphology and the volume fraction of the dendrites, on the ciscous flow at various strain rates and at elevated temperatures. Finally, the deformation behavior at elevated temperatures between monolithic bulk metallic glass, partially nanocrystallized bulk metallic glass and bulk metallic glass composite with ductile phase will be systematically investigated and compared. This will be also helpful to understand the generation, movement and interaction of shear bands between the amorphous phase, the nanocrystals, and the micrometer- sized dendrites