EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Metallic glasses (MGs) have been intensively studied since the 60’s, for their amorphous structure, their global chemical homogeneity and their lack of crystallographic defects, leading to unique characteristics. From a mechanical viewpoint, MGs are characterized by outstandingly high elastic domain and maximal strength, compared to their crystalline counterparts. Although they are macroscopically weak at room temperature, they are highly ductile under high temperature [1]. However, applications of MGs stay limited, due to fast quenching necessary to limit the crystallization process during the manufacturing process. As a result, only small pieces of multicomponent chemical materials can be obtained in the bulk state. The condensation from the vapor phase to form a solid film in physical vapor deposition (PVD) is another way to design metallic glasses. Compared to bulk MGs, thin film metallic glasses (TFMGs) show particular interest in terms of wide range of chemical compositions and enhanced ductility [2]. Nevertheless, due to their thin film nature, dedicated characterization techniques, suitable for small-scale systems, must be used for TFMGs characterization. In particular, there is a need for characterization techniques to monitor the mechanical evolution of TFMGs with temperature.
Here, high temperature scanning indentation (HTSI) [3], which is based on high speed nanoindentation during thermal cycles, is used to measure mechanical properties of model ZrCu-TFMGs at high temperature. The purpose is to use nano-hardness as a “DSC-like” technique to perform real-time observations of physical changes. The different transitions occurring within the coatings (i. e. metallic glass to supercooled liquid transition, crystallization…) are discussed in light of the mechanical response. HTSI results are also compared with more usual techniques, including differential scanning calorimetry and high temperature X-Ray Diffraction.
[1] Spaepen, Acta Mater. 1977
[2] Chu et al., JOM 2010
[3] Tiphéne et al., JMR 2021 (accepted)