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

在本项目中，我们将用透射电子显微镜研究Zr55Cu30Ni5Al10块体金属玻璃的详细纳米化过程，并与两种样品在高应变率和高温下变形后的部分纳米化的Zr55Cu30Ni5Al10块体金属玻璃进行比较。通过对不同类型样品的比较，可以了解纳米化对高温变形行为的影响，以及关于新纳米化相与先前热处理获得的部分纳米化相之间的反应从非均匀流动到均匀流动的转变。此外，为了控制和建立不同的树枝晶长度和体积分数，从而了解树枝晶形态和体积分数对不同应变速率和高温下的顺流的影响，优化具有韧性树枝晶的大块金属玻璃复合材料的铸造条件是很有意义的。最后，系统地研究和比较了整体块体金属玻璃、部分纳米化块体金属玻璃和含延性相的块体金属玻璃的高温变形行为。这也将有助于理解非晶相、纳米晶和微米级枝晶之间剪切带的产生、运动和相互作用。

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