Flash-annealed metastable alloys with novel microstructures and surface topographies

目前的建议侧重于研究快速加热的大块金属玻璃（bmg）的基础科学和技术方面，以创造新的亚稳材料。在这种闪蒸退火处理过程中，热塑性成形（TPF）被额外应用于调整bmg的表面形貌，使其表面功能化。因此，BMG是一种粘性亚稳液体，具有高变形能力，可以精确地复制微、纳米级和分层结构。因此，人们可以调整具有超疏水和/或亲湿特性的表面形貌。特别地，研究了表面结构的润湿特性、粗糙度和纵横比之间的关系。这种表面对于具有自清洁效果的材料或作为植入物具有很高的兴趣。在闪蒸退火过程中，bmg结晶形成具有新型微观结构的亚稳材料。相的形成取决于加热速率，并且可以控制。此外，结晶发生在大过冷时，这伴随着高成核和较低的晶体生长速率。因此，bmg的闪蒸退火可以形成高强度和最好的延展性材料，具有细晶到纳米晶，并且在适当的工艺控制下甚至可以形成双峰微结构。其机械性能应进行深入表征。到目前为止，对bmg闪蒸退火制备的材料及其产生的现象的研究还很少，是一个新的研究领域。研究了Cu44Zr44Al8Hf2Co2和Ti40Zr10Cu34Pd14Sn2两种不同晶化机制的玻璃成形合金的相形成和结晶动力学随升温速率的变化规律。cuzr基合金具有具有形状记忆效应的高温相，其显微组织可以通过闪蒸退火获得。钛基合金具有生物相容性，可作为植入材料。生物相容性还取决于表面的润湿特性，并可通过使用TPF进行适当的表面结构来增强。因此，在当前提案的框架内，将开发一个实现热塑性压花的单元，并将其集成到现有的闪蒸设备的基础设施中。当前提议的优越目标是创造具有增强机械和表面性能的材料，这是传统金属材料无法达到的，以扩大亚稳合金的应用范围。

The current proposal focuses on the investigation of fundamental scientific as well as technological aspects of bulk metallic glasses (BMGs) subjected to rapid heating in order to create novel metastable materials. In the course of this flash-annealing treatment, thermoplastic forming (TPF) is additionally applied to adjust the surface topography of the BMGs enabling the functionalization of their surface. Thereby, the BMG is present as a viscous metastable liquid with high deformability allowing the precise replication of micro-, nanoscale and hierarchical structures. Thus, one can adjust surface topographies with superhydrophobic and/ or –philic wetting characteristics. Particularly, the correlation between wetting characteristics, roughness, and aspect ratio of the surface structures is investigated. Such surfaces are of high interest for materials with a self-cleaning effect or as implants.During flash-annealing BMGs are crystallized in order to create metastable materials with novel microstructures. The phase formation depends on the heating rate and can be controlled. Furthermore, crystallization occurs at large undercoolings which are accompanied by high nucleation and lower crystal growth rates. Thus, flash-annealing of BMGs enables the formation of high-strength and at best ductile materials with fine-grained to nanocrystalline and at suitable process control even bimodal microstructures. Their mechanical properties shall be characterized in depth.So far, materials created from flash-annealing of BMGs as well as the thereby arising phenomena have been hardly studied and, thus, represent a new research field. The phase formation and crystallization kinetics as a function of the heating rate shall be investigated for two selected glass-forming alloys with different crystallization mechanisms: Cu44Zr44Al8Hf2Co2 and Ti40Zr10Cu34Pd14Sn2. The CuZr-based alloy has a high-temperature phase showing the shape memory effect and the resulting microstructures which could be obtained by flash-annealing are of high interest. The Ti-based alloy is biocompatible and could be used as implant material. The biocompatibility also depends on the wetting characteristics of the surface and could be enhanced by an appropriate surface structuring using TPF.Therefore, within the framework of the current proposal, a unit enabling thermoplastic embossing is going to be developed and integrated into the infrastructure of the already existing flash-annealing device.The superior objective of the current proposal is the creation of materials with enhanced mechanical and surface properties, which cannot be attained by conventional metallic materials, in order to enlarge the range of application for metastabile alloys.