The glass-forming ability of Zr–Cu-based metallic glass with high entropy is investigated. Samples are prepared by adding elements, such as Ag, Hf, and Ni, to ternary Zr48Al7Cu45 to systematically ...evaluate the multicomponent effect. The glass structures are fabricated by tilt casting. In quaternary and senary alloys with increased glass-forming ability, new competitive liquid crystalline phases are generated with the addition of elements. Compared with the quaternary alloy, the quinary alloy does not form a new crystalline phase, and the added Hf is highly soluble in the base crystalline phase. The driving force for crystallization, which is evaluated based on specific heat measurements, is the largest for the quinary alloys. This suggests that stabilization of the competitive phase by the high-entropy effect leads to a decrease in the glass-forming ability. From the kinetics point of view, the relationship between the liquid-phase fragility and glass-forming ability is clarified, and the addition of Ag and Ni, which strengthens the liquid properties, is found to improve the glass-forming ability. Based on the high-entropy strategy, a new high-entropy metallic glass Zr35Hf13Al11Ag8Ni8Cu25, with a maximum vitrification diameter of 20 mm, is fabricated.
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•The glass-forming ability of metallic glasses did not increase monotonically with increase configuration entropy.•When the high-entropy effect occurs in the crystalline phase, the glass-forming ability is reduced.•The driving force of the crystallization and the fragility index of alloys were correlated with the glass-forming ability.•The largest Be-free high-entropy bulk metallic glass with a maximum vitrification diameter of 20 mm, was newly fabricated.
We studied the features of CuSbS2 (CAS) and CuSbSe2 (CASe), two proposed photovoltaic compounds, and clarified their electronic structures by first-principles calculations and compared them to the ...chalcopyrite-type CuInSe2 results. For both CAS and CASe, the calculated enthalpies of formation of the chalcostibite phases were considerably lower than those of the chalcopyrite phases. Therefore, we considered that the chalcostibite phase is more stable for CAS and CASe. In their band structure calculated with the HSE06 hybrid functional, the valence band maxima of CAS and CASe were located at the Γ-point, and the conduction band minima were located at the R-point. Their second lowest conduction band was located at the Γ-point, whose energy level nearly equaled the R-point. For CAS (CASe), the partial density of the states shows the character of the Cu 3d and S 3p (Se 4p) orbitals at the top of the valence bands and the Sb 5p and S 3p (Se 4p) orbitals at the bottom of the conduction bands. The conduction bands of CAS and CASe have a p-orbital character (Sb 5p) that differs from the s-orbital character (In 5s) of CuInSe2. It is for the reason that CAS and CASe do not have a chalcopyrite structure but a chalcostibite-type structure. The calculated absorption coefficient of CuSbS2 (104–105cm−1) is comparable to that of CuInSe2.
•We studied the features of CuSbS2 and CuSbSe2, newly proposed photovoltaic compounds.•Chalcostibite phase is more stable in CuSbS2 and CuSbSe2.•Band structures of CuSbS2 and CuSbS2 were calculated with HSE06 hybrid functional.•Absorption coefficient of chalcostibite-type CuSbS2 is comparable to that of CuInSe2.
Lacking the structural information of crystalline solids, the origin of the relaxation dynamics of metallic glasses is unclear. Here, we report the evolution of stress relaxation of high-entropy ...metallic glasses with distinct β relaxation behavior. The fraction of liquidlike zones, determined at each temperature by the intensity of stress decay, is shown to be directly related to both the aging process and the spectrum of relaxation modes obtained by mechanical spectroscopy. The results shed light on the intrinsic correlation between the static and dynamic mechanical response in high-entropy and conventional metallic glasses, pointing toward a sluggish diffusion high-entropy effect in the liquid dynamics.
The relationship between white matter disruption and cognitive dysfunction of patients with mTBI in the chronic stage remains unclear. The aim of this study was to identify white matter integrity by ...using DTI in patients with mTBI without morphologic traumatic abnormalities seen with conventional imaging and to evaluate the association of such regions with cognitive function.
Diffusion tensor images from 51 consecutive patients with mTBI without morphologic traumatic abnormalities on conventional MRI were processed, and FA maps were generated as a measure of white matter integrity. All subjects underwent cognitive examinations (MMSE and WAIS-R FIQ). Correlations between the skeletonized FA values in the white matter and the cognitive function were analyzed by using regression analysis.
In patients with mTBI, significantly decreased FA value clusters in the white matter compared with the healthy controls were found in the superior longitudinal fasciculus, superior frontal gyrus, insula, and fornix. Cognitive examination scores positively correlated with FA values in a number of regions in deep brain structures, which were anatomically close or physiologically intimate to the regions with significant FA value reduction, in patients with mTBI.
The present study shows that patients with mTBI in the chronic stage have certain regions with abnormally reduced white matter integrity in the brain. Although the clinical and pathologic-anatomic correlation of these findings remains to be elucidated, these brain regions are strongly suggested to be related to chronic persistent cognitive impairments in these patients.
A senary ScYLaTiZrHf alloy was investigated for its ability to form a solid solution with an hcp structure, also known as a high-entropy alloy (HEA). X-ray diffraction analysis of the ScYLaTiZrHf ...alloy produced by arc-melting method confirmed this hcp structure. The microstructure of the ScYLaTiZrHf was composed of dual phases that were enriched in (Y, La) or (Ti, Zr, Hf), with Sc distributed evenly across both phases. The positive mixing enthalpy of 11.4 kJ mol−1 derived from Miedema's model, and the immiscible tendencies of its constituent binary phase diagrams help to explain the presence of dual phases in the ScYLaTiZrHf alloy. When formed into dual hcp solid solutions, the ScYLaTiZrHf alloy can be more accurately described as a multi-principal-element alloy (MPEA) rather than as a HEA, since the ScYLaTiZrHf alloy is a solid solution that is enthalpy-driven instead of entropy driven. The results also disclosed another procedure to stabilize solid solutions excepting for high-entropy scheme.
•Dual hcp structures form in ScYLaTiZrHf alloy comprising transition metals mainly.•The ScYLaTiZrHf alloy is regarded as a multi-principal-element alloy.•The ScYLaTiZrHf alloy is a prototypical high-entropy alloy with hcp structure.
Environmental radioactive contamination caused by the Fukushima Dai-ichi Nuclear Power Plant accident has aroused great concern regarding a possible increase in the incidence of childhood thyroid ...cancer. The ultrasound examinations were conducted immediately after the accident as part of the Fukushima Health Management Survey (FHMS), which is divided into the preliminary baseline survey (PBLS) and the full-scale survey (FSS). Some of their outcomes are reported regularly and made available to the public. We have detailed measurements of the air-dose rates and radioactive elements in soil in many places all over the Fukushima prefecture. To study the dose-response relationship, we begin with the assumption that the external and internal doses are correlated with the air-dose rate and the amount of
I in soil, respectively. We then investigate the relationship between these estimated doses and the PBLS and FSS thyroid cancer cases. Our analysis shows that the dose-response curve with the FSS data clearly differs from that with the PBLS data. Finally, we consider the potential mitigating effects of evacuation from highly contaminated areas in both external and internal exposure scenarios.
MR imaging can reflect the pathologic progression of carcinoma ex pleomorphic adenoma (CXPA). This study aimed to identify the imaging findings related to extracapsular invasion of CXPA. ...Additionally, the pathologic background of these findings was investigated.
This retrospective study included 37 patients with histologically confirmed CXPA. Three radiologists independently evaluated whether the CXPA showed the following characteristic MR imaging findings: border, capsule, the corona sign on fat-saturated T2WI and contrast-enhanced fat-saturated T1WI, and the black ring sign. The corona sign appeared larger on fat-saturated and/or contrast-enhanced fat-saturated T1WI than on T1WI. The black ring sign was defined as an intratumoral nodule with a thick low-intensity rim on T2WI. Interreader agreement of the visual assessment was performed using κ analysis, and MR imaging and histopathologic findings were also correlated. Kaplan-Meier survival and the log-rank test were used to estimate the 3-year disease-free survival.
MR imaging findings, especially peritumoral findings, showed a significant difference between invasive and noninvasive CXPA. The reliability was poor for the border and capsule. In contrast, it was good for the corona sign on fat-saturated and contrast-enhanced fat-saturated T1WI and the black ring sign. Pathologically, the corona sign reflected the invasiveness of the tumor and inflammatory cells, while the black ring sign reflected hyalinization or fibrosis. The corona sign also showed a significant difference in the 3-year disease-free survival.
MR imaging findings, including the corona and black ring signs, reliably differentiated invasive and noninvasive CXPA. The corona sign can be used as a prognostic factor for CXPA.
We consider a system described by a Fokker-Planck equation with a new type of momentum-dependent drift coefficient which asymptotically decreases as -1/p for a large momentum p. It is shown that the ...steady-state of this system is a κ-generalized Gaussian distribution, which is a non-Gaussian distribution with a power-law tail.
In TiNi-based crystalline/amorphous alloys, superelasticity in crystalline phase coordinating the dislocation sinking in amorphous phase lead to a high ductility and outstanding anti-fatigue ...properties. We performed cryogenic thermal cycling, between 77 K and 303 K, on the complex TiNi-based alloys consisting of a major B2 austenite phase, an interdendritic amorphous phase, and a minor B19′ martensite phase in the as-cast state. The critical martensitic phase transformation stress (σm) increased with the number of thermal cycles, reaching a maximum at 10 cycles. The initial B19’ martensite which is confined in the amorphous phase transformed to B2 austenite due to thermal induced stable transformation. A lamellar structure of alternating amorphous and crystalline layers dominantly grew into the amorphous matrix as a consequence of the thermal fatigue during the cryogenic thermal cycling. Initial cell for the molecular dynamic simulations was carefully prepared to contain three different phases. Cyclic compressive loading and cryogenic thermal cycling simulations were consistent with the experimental results.
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•TiNi composite was designed with excellent combination of strength and ductility.•Cryogenic thermal cycling induces an increase in σm which is improve the fatigue.•The amorphous phase in the composite plays an important role in thermal cycling process.
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