Bioinspired ceramics with micron-scale ceramic “bricks” bonded by a metallic “mortar” are projected to result in higher strength and toughness ceramics, but their processing is challenging as metals do not typically wet ceramics. To resolve this issue, we made alumina structures using rapid pressureless infiltration of a zirconium-based bulk-metallic glass mortar that reactively wets the surface of freeze-cast alumina preforms. The mechanical properties of the resulting Al 2 O 3 with a glass-forming compliant-phase change with infiltration temperature and ceramic content, leading to a trade-off between flexural strength (varying from 89 to 800 MPa) and fracture toughness (varying from 4 to more than 9 MPa·m ½ ). The high toughness levels are attributed to brick pull-out and crack deflection along the ceramic/metal interfaces. Since these mechanisms are enabled by interfacial failure rather than failure within the metallic mortar, the potential for optimizing these bioinspired materials for damage tolerance has still not been fully realized.

We present the results of a structural study of metallic alloy liquids from high temperature through the glass transition. We use high energy X-ray scattering and electro-static levitation in combination with molecular dynamics simulation and show that the height of the first peak of the structure function, S(Q) − 1, follows the Curie-Weiss law. The structural coherence length is proportional to the height of the first peak, and we suggest that its increase with cooling may be related to the rapid increase in viscosity. The Curie temperature is negative, implying an analogy with spin-glass. The Curie-Weiss behavior provides a pathway to an ideal glass state, a state with long-range correlation without lattice periodicity, which is characterized by highly diverse local structures, reminiscent of spin-glass.

It is difficult to characterize by experiment the structural features of liquids and glasses which lack long-range translational periodicity in the structure. Here we suggest that the height and shape of the first peak of the structure function, S(Q), carry significant information about the nature of the medium-range order and the coherence of density correlations. It is further proposed that they indicate how ideal the liquid structure is. Here the ideal state is defined by long-range density correlations, not by structural coherence at the atomic level. The analysis is applied to the S(Q) of metallic alloy liquids determined by X-ray diffraction and simulation.The ideality index defined here may provide a common parameter to characterize structural coherence among various disparate groups of liquids and glasses.

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In this paper, we propose a new parameter for glass-forming ability (GFA) based on the combination of thermodynamic (stability of stable and metastable liquids by ΔTm = Tmmix − Tl and ΔTx = Tx − Tg, respectively) and kinetic (resistance to crystallization by Tx) aspects for glass formation. The parameter is defined as ε = (ΔTm + ΔTx + Tx)/Tmmix without directly adding Tg while considering the whole temperature range for glass formation up to Tmmix, which reflects the relative position of crystallization curve in continuous cooling transformation diagram. The relationship between the ε parameter and critical cooling rate (Rc) or maximum section thickness for glass formation (Zmax) clearly confirms that the ε parameter exhibits a better correlation with GFA than other commonly used GFA parameters, such as ΔTx (=Tx − Tg), K (=[Tx − Tg]/[Tl − Tx]), ΔT*(=(Tmmix − Tl)/Tmmix), Trg (=Tg/Tl), and γ (=[Tx]/[Tl + Tg]). The relationship between the ε parameter and Rc or Zmax is also formulated and evaluated in the study. The results suggest that the ε parameter can effectively predict Rc and Zmax for various glass-forming alloys, which would permit more widespread uses of these paradigm-shifting materials in a variety of industries.

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Electrolyte solutions are ubiquitous in materials in daily use and in biological systems. However, the understanding of their molecular and ionic dynamics, particularly those of their correlated motions, are elusive despite extensive experimental, theoretical, and numerical studies. Here we report the real-space observations of the molecular/ionic-correlated dynamics of aqueous salt (NaCl, NaBr, and NaI) solutions using the Van Hove functions obtained by high-resolution inelastic X-ray scattering measurement and molecular dynamics simulation. Our results directly depict the distance-dependent dynamics of aqueous salt solutions on the picosecond time scale and identify the changes in the anion−water correlations. This study demonstrates the capability of the real-space Van Hove function analysis to describe the local correlated dynamics in aqueous salt solutions.