Mechanisms of Nanoglass Ultrastability

The origin of the astonishing properties of recently discovered ultrastable nanoglasses is presently not well understood. Nanoglasses appear to exhibit density variations not common in bulk glasses and differ significantly in thermal, magnetic, biocompatible, and mechanic properties from the bulk materials of the same composition. Here, we investigate a generic model system that permits modeling of both the physical vapor deposition process (PVD) of the nanoparticles and their consolidation into a nanoglass. We performed molecular dynamics simulations to investigate the PVD process generating nanometer-sized noncrystalline clusters and the formation of the PVD-nanoglass when these nanoclusters are consolidated. In agreement with the experiments, we find that the resulting PVD-nanoglass consists of two structural components: noncrystalline nanometer-sized cores and interfacial regions that are formed during the consolidation process. The interfacial regions were found to have an atomic structure and an internal energy that differ from the structure and internal energy of the corresponding melt-quenched glass. The resulting material represents a noncrystalline state that differs from a bulk glass with the same chemical composition and a glass obtained from nanoparticles derived from the bulk glass

Mechanisms of Nanoglass Ultrastability

The origin of the astonishing properties of recently discovered ultrastable nanoglasses is presently not well understood. Nanoglasses appear to exhibit density variations not common in bulk glasses and differ significantly in thermal, magnetic, biocompatible, and mechanic properties from the bulk materials of the same composition. Here, we investigate a generic model system that permits modeling of both the physical vapor deposition process (PVD) of the nanoparticles and their consolidation into a nanoglass. We performed molecular dynamics simulations to investigate the PVD process generating nanometer-sized noncrystalline clusters and the formation of the PVD-nanoglass when these nanoclusters are consolidated. In agreement with the experiments, we find that the resulting PVD-nanoglass consists of two structural components: noncrystalline nanometer-sized cores and interfacial regions that are formed during the consolidation process. The interfacial regions were found to have an atomic structure and an internal energy that differ from the structure and internal energy of the corresponding melt-quenched glass. The resulting material represents a noncrystalline state that differs from a bulk glass with the same chemical composition and a glass obtained from nanoparticles derived from the bulk glass

Ni-P nanoglass prepared by multi-phase pulsed electrodeposition

<p>Ni-P nanoglass consisting of nanometer-sized amorphous grains separated by amorphous interfaces was prepared by a specially designed multi-phase pulsed electrodeposition technique. The microstructure of the deposited Ni-P nanoglass was confirmed by X-ray diffraction, high-resolution transmission electron microscopy, small-angle X-ray scattering, and X-ray photoelectron spectroscopy. The formation of the Ni-P nanoglass, which is characterized by inhomogeneities on the nanometer length scale, is achieved via proper control of the rate of cluster formation and cluster growth by a multi-phase pulsed electrodeposition process.</p

Low temperature structural stability of Fe₉₀Sc₁₀ nanoglasses

<p>The structural stability of Fe₉₀Sc₁₀ nanoglasses has been studied by means of low temperature crystallization. Specimens were annealed <i>in situ</i> in a transmission electron microscope, and <i>ex situ</i> in an ultra-high vacuum tube-furnace. Both studies led to similar results. The structure of the Fe₉₀Sc₁₀ nanoglasses was stable for up to 2 h when annealed at 150°C. Annealing the Fe₉₀Sc₁₀ nanoglasses at higher temperature resulted in the formation of the nanocrystalline bcc-Fe(Sc).</p> <p><b>Impact statement</b></p> <p>The structural evolution of Fe₉₀Sc₁₀ nanoglasses has been studied in detail during low temperature annealing. Our results indicate that the nanostructure of Fe₉₀Sc₁₀ nanoglasses is quite stable at low temperature.</p

Enhanced inter-diffusion of immiscible elements Fe/Cu at the interface of FeZr/CuZr amorphous multilayers

<p>Fe₇₅Zr₂₅/Cu₆₄Zr₃₆ amorphous multilayers were prepared by magnetron sputtering. Atom probe tomography was employed to analyze the atomic inter-diffusion at the interface of the multilayers before and after annealing (573 K, 60 min). An unexpected enhanced inter-diffusion of the immiscible elements Fe and Cu was detected at the interface of the multilayers. As the inter-diffusion in amorphous multilayers is much faster than that in the crystalline counterparts, this process may open a way to manipulate or create amorphous multilayers with new properties. This idea agrees with the observation of the variation of magnetic properties of Fe₇₅Zr₂₅/Cu₆₄Zr₃₆ amorphous multilayers.</p> <p><b>IMPACT STATEMENT</b> This paper reveals the enhanced atomic inter-diffusion at the interface of amorphous materials, and may open a way to manipulate or create amorphous multilayers with new properties.</p

Nanoscale Structural Evolution and Anomalous Mechanical Response of Nanoglasses by Cryogenic Thermal Cycling

One of the central themes in the amorphous materials research is to understand the nanoscale structural responses to mechanical and thermal agitations, the decoding of which is expected to provide new insights into the complex amorphous structural-property relationship. For common metallic glasses, their inherent atomic structural inhomogeneities can be rejuvenated and amplified by cryogenic thermal cycling, thus can be decoded from their responses to mechanical and thermal agitations. Here, we reported an anomalous mechanical response of a new kind of metallic glass (nanoglass) with nanoscale interface structures to cryogenic thermal cycling. As compared to those metallic glasses by liquid quenching, the Sc₇₅Fe₂₅ (at. %) nanoglass exhibits a decrease in the Young’s modulus but a significant increase in the yield strength after cryogenic cycling treatments. The abnormal mechanical property change can be attributed to the complex atomic rearrangements at the short- and medium- range orders due to the intrinsic nonuniformity of the nanoglass architecture. The present work gives a new route for designing high-performance metallic glassy materials by manipulating their atomic structures and helps for understanding the complex atomic structure–property relationship in amorphous materials