Quantum mechanically guided design of ultra strong and damage tolerant glasses

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Co-based bulk glassy alloys have high mechanical strength and stiffness as well as good soft magnetic properties. Co43Fe20Ta5.5B31.5 exhibits a strength of 5185 GPa and an elastic modulus of 268 GPa [Inoue et al., Nat. Mater. 2003]. Metallic glasses were developed mostly based on phenomenological glass forming rules. As quantum mechanical calculations of materials in the glassy state are challenging, most topological descriptions of metallic glasses are so far based on reversed Monte Carlo approaches. Hence, basic physical and chemical materials design principles for metallic glasses have not been identified. This project aims at identifying and understanding these principles to realize future knowledge-based design of metallic glasses with high strength and stiffness as well as toughness. Based on ab initio molecular dynamics simulations [Hostert et al., J. Phys.: Cond. Mater. 2011] stiffness as well as toughness of Co43Fe20Ta5.5B31.5-xNMx (NM = C, N, O) and Co43Fe20-yTMyTa5.5B31.5 (TM = Zr, Nb, Mo, Hf, W) metallic glasses alloy systems suitable for experiments are determined, synthesized and characterized. We systematically explore the influence of the chemical composition on the electronic structure, topology, stiffness and toughness. We will synthesize Co-based metallic glasses using a thin film combinatorial approach. It enables the efficient investigation of a multi-component system in a limited number of experiments. The ab initio molecular dynamics data are compared to the experimental data of the stiffness, the elastic plastic transition, the density and the chemical order. Topological and chemical ordering is analyzed by atom probe tomography (LEAP 3000X HR) and by selected area electron diffraction. It is envisioned that based on this combined theoretical and experimental research strategy the basic physical and chemical design principles required to realize future knowledge-based design of metallic glasses with high strength and stiffness as well as toughness can be identified.