MMCs reinforced with metallic glasses
Metallic glasses are extremely attractive as reinforcing agents in MMCs because of their remarkable mechanical properties, including high yield strength (1-4 GPa) and large elastic strain (~2 %). In addition, they may yield an improved interface between matrix and particles with respect to the more conventional ceramic reinforcements. In our work [1-5], different classes of metallic glass powders are used as reinforcement for metallic matrices. The glass-composite powders are consolidated by hot pressing and hot extrusion into bulk specimens with nearly full density by taking advantage of the reduced viscosity of the glassy particles at temperatures above the glass transition. The consolidation of glassy powders is not an easy task and the accurate control of the operational conditions, e.g., pressure, temperature and holding time, is crucial in order to obtain fully dense specimens without inducing the crystallization of the glass reinforcement during consolidation. To reach this aim, the detailed knowledge of the crystallization behavior and the temperature dependence of the viscosity of the glassy phase is an essential prerequisite to select the proper sintering parameters (Figure 1).
Main aim of our work is the investigation of the physical and mechanical properties of the composites. The addition of the glass reinforcement is very effective for improving the room temperature mechanical properties of the matrix. Depending on the type of metallic glass reinforcement used (Al-, Fe-, Mg-, Ni-, or Zr-based), the yield and compressive strengths may exceed that of the unreinforced matrix by a factor of 2-3, while retaining appreciable plastic deformation (Figure 2).
Another focus of our research is the description of the overall mechanical behavior of a composite from the properties of the single constituents, which is an important requirement for materials design and application. The mechanical properties of the composites have been modeled by using different approaches, ranging from the simple rule of mixture to more advanced methods, such as shear lag model and self-consistent effective medium approach (Figure 3). Important conclusions regarding the effect of the distribution of the particles, their contiguity and cracking can be obtained, giving additional possibilities to design and further improve the properties of the composites.
 J.Y. Kim, S. Scudino, B.S. Kim, M.H. Lee, U. Kühn, J. Eckert, Metals 2 (2012) 79.
 S. Scudino, K.B. Surreddi, S. Sager, M. Sakaliyska, J.S. Kim, W. Löser, J. Eckert, J. Mater. Sci. 43 (2008) 4518.
 Z. Wang, J. Tan, B. A. Sun, S. Scudino, K.G. Prashanth , W.W. Zhang, Y.Y. Li, J. Eckert, Mater. Sci. Eng. A 600 (2014) 53.
 S. Scudino, G. Liu, K.G. Prashanth, B. Bartusch, K.B. Surreddi, B.S. Murty, J. Eckert, Acta Mater. 57 (2009) 2029.
 Z. Wang, S. Scudino, M Stoica, W.W. Zhang, J. Eckert, J. Alloys Comp. 651 (2015) 170.