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In this paper, a broadband tri-polarization reconfigurable antenna applied to polarization diversity is proposed. A partially reflective surface (PRS) is designed to form an air-filled resonator cavity. The reflection phase of the PRS has a positive phase gradient in order to achieve the characteristics of the proposed antenna gain enhancement in the wideband. A metal patch of a four-arm meander structure is used as the radiation structure and the feeding is realized through a four-channel rotating feeding network with equal amplitude and 90∘ phase difference. The feeding network is connected to the radiation structure through four metallized vias. In order to realize the polarization reconfigurability, the PIN diodes and the corresponding DC bias circuit are integrated in the rotating feeding network. The characteristics of horizontal polarization (HP), vertical polarization (VP) and right-hand circular polarization (RHCP) are realized by changing the ON/OFF states of PIN diodes integrated in the feeding network. In order to verify the performance of the proposed antenna, fabrication and testing were carried out. The measurement results show that the -10 dB impedance bandwidths of HP, VP, RHCP are 11% (12.5-14 GHz), 6.4% (13.7-14.6 GHz) and 20% (12.2-14.9 GHz), and the peak realized gains are 9.1, 9.2 and 11.5 dBi, respectively. For RHCP mode, the 3-dB axial ratio bandwidth reaches about 17% (12.35-13.4 GHz and 13.6-14.9 GHz).

The implantable antenna is an important part of the wireless capsule endoscopy (WCE) system to achieve wireless communication. This paper designed an ultra-wideband flexible implantable antenna for wireless capsule endoscopy system. With a very wide bandwidth, the antenna can completely cover the industrial, scientific, and medical frequency bands (ISM, 2.4-2.48 GHz) and Wireless Medical Telemetry Service (WMTS, 1.395-1.4 GHz). The expanded size of the proposed antenna is 18mm× 10mm× 0.1mm. The conformal technology of the antenna has further reduced the space of the system and achieved miniaturization. The capsule antenna in this paper is a compact planar monopole antenna fed by a coplanar waveguide, and it uses a flexible material as a dielectric substrate to achieve the conformal shape of the antenna. U-shaped ground branch (UGB) and a loaded split ring resonator (SRR) structure were used to further improve the antenna performance. Simulation and measurement results were basically the same. On the premise of radiation safety and miniaturization of the antenna, the ultra-wideband operation of the antenna was realized. This antenna design provided reference value for the design and application of the capsule antenna.

The available experimental self-diffusion coefficients of twenty-two liquid elements near their melting temperatures are compared with the calculated data by the first-principal dynamics simulation. The holistic evaluation shows that the calculated self-diffusion coefficients are in reasonable agreement with the experimental data. For liquid metals with loose-packed structure, the self-diffusion coefficient decreases in general with the increase of packing fraction. For liquid metals with close-packed structure in which the coordination number is larger than 11.5, the self-diffusion coefficient fluctuates around 2.0×10-9 m2s-1, except for liquid Al, Ti and Li of which the self-diffusion coefficients are anomalously large. The packing fraction can only partially account for the self-diffusion coefficient of liquid metals.

International audience; Based on the time-temperature-transformation interpretation, a new criterion for glass forming ability, Z = [(Tx-Tg)/(Tl-Tg)][(Tl–Tl(c))/(Tl-Tg)]0.556, is proposed, where Tg, Tx, Tl and Tl(c) respectively denote the glass transition temperature, the onset crystallization temperature upon heating, the liquidus temperature and the onset solidification temperature of the liquid upon cooling. The Z parameter jointly considers the stability of the liquid and the devitrification of glassy phases. A non-linear relationship between the parameter Z and the critical glassy size dc has been found to be log (dc)cal = 0.1392 + 17.0616Z - 41.985(Z)2, showing stronger correlation than other earlier reported parameters. The advantage of using Z as a GFA parameter is that it roughly reflects the relative influences of the thermodynamics and kinetics of the systems on glass formation. In addition, the parameter describes the stability of liquid in the course of being quenched from above liquidus temperature.

Bond breaking related with plastic deformation in a deformed metallic glass Zr50Cu50 is investigated by molecular dynamics simulations. The results show that the spatial distributions of broken bonds are closely correlated with local shear strains, and the clustering behaviors of atoms with broken bonds (flow defects) are characterized with different stages of plastic deformation. The average distance among those clusters of flow defects decreases as the strains increase, which follows the curvature quadrupole model for flow defects in ideal amorphous solids. For the first time, the features of bond breaking processes are quantitatively measured with the chemical composition, bond length and orientation, bond pairs, local five-fold symmetry and quasi-nearest atoms, whose threshold values are important factors that could characterize the flow defects in metallic glasses under plastic deformation. The shape, orientation and energetics of flow defects quantitatively characterized by the bond breaking analysis thus facilitate our understanding on the deformation mechanisms in metallic glasses.

An attempt is carried out to design metallic glasses by modifying the local structure of icosahedral quasicrystals. A series of metallic glasses are prepared by introducing beryllium to the quasicrystal former, Zr40Ti40Ni20, and the maximum diameter of the glasses reaches 20 mm. A phase transformation diagram is constructed for the alloys of (Zr40Ti40Ni20)100-xBex, revealing the transition from stable crystal to quasicrystal and then to metallic glasses with the increased Be content. This study shows a connection between the formation of metallic glasses and the specific thermodynamics of the initially precipitated quasicrystals. Interestingly, both improvements in the forming ability for glasses and quasicrystals are observed over a wide composition range. Ab initio molecular dynamic simulations show the evolution of the structural features of the metallic melts for the optimised glass forming region, which guarantee the primary precipitation of quasicrystal.

Hydrogenation properties of two five-component Mg60Ce10Ni20Cu5X5 (X = Co, Zn) metallic glasses have been studied. Using high-pressure differential scanning calorimetery (HP-DSC) under hydrogen atmosphere and hydrogenation kinetics study, it is demonstrated that alloying with Zn shows negligible impact on the hydrogenation kinetics and storage capacity of the Mg Ce Ni Cu metallic glass, however, alloying with Co remarkably improves the hydrogenation kinetics and storage capacities. Apparent activation energies for hydrogenation are calculated to be 64.4 kJ/mol, and 107.2 kJ/mol, for the Mg60Ce10Ni20Cu5Co5 and Mg60Ce10Ni20Cu5Zn5 metallic glasses, respectively. Theoretical calculations are performed to understand the atomic structure of the five-component metallic glasses. It shows that the overall, Mg Mg pair and Mg Ni pair distribution functions (PDFs) of the Mg60Ce10Ni20Cu5Co5 and Mg60Ce10Ni20Cu5Zn5 metallic glasses are almost the same, indicating that geometry issue is not a key factor on influencing the hydrogenation properties of the studied Mg-based metallic glasses. It is proposed that chemical composition is the key to improve the hydrogenation properties of Mg-based metallic glasses.

The atomic structures of Zr50Cu50 metallic glasses (MGs) under high pressures from 0 GPa to 150 GPa are investigated via molecular dynamics simulations. We found that as pressure and density increase, local structural parameters such as coordination number, five-fold symmetry and quasi-nearest atom reach maxima (or minima) at 60 GPa, rather than monotonous pressure dependence. Atomic structure analyses uncover unexpected shortening of Zr-Zr bonding of Zr50Cu50 MGs under high pressures, responsible for the change of atomic packing in Zr50Cu50 MGs from dense to loose while pressure increasing. Furthermore, composition segregation is observed at high pressures, resulted from the new finding that the Zr-Zr and Cu-Cu bonding are much easier to decrease than Zr-Cu under high pressures. The results help to understand the behaviors of metallic glasses under extreme conditions.

We observed the transition of medium-range orders (MROs) and physical properties in liquid Fe–Al alloys by using ab initio molecular dynamics simulation. Above 66 at. % Al, only Fe–Fe MRO exists, while in other binary Fe–Al alloys studied Fe–Fe and Al–Al MROs coexist, and below 50 at. % Al, Al–Al MRO turns to be dominant. The curve of short-range order around Fe atoms versus Al content also shows a juncture at 66 at. % Al above which polyhedron type increase significantly, correspondingly a significant decrease of the average magnetic moment per Fe atom is observed. In addition, the self-diffusion coefficient of Al atom increases sharply above 66 at. % Al.

The atomic structure and corrosion behavior of Fe87-xB13Nbx (x = 0, 7, 10 and 13) metallic glasses were investigated using various experimental techniques and simulations. The netlike (Fe, Nb)23B6 structure units, which took root in the Nb-contained amorphous matrix, emerged after annealing and raised markedly corrosion resistance of as-spun amorphous samples as cNb > 7 at.%, such as the occurrence of wider passive platform in the potentiodynamic polarization plots and the transformation from the porous holes to stable passive films on corrosion surfaces.

Rejuvenation is the structural excitation of metallic glasses that can significantly increase the enthalpy and free volume. Here, the rejuvenation in Zr46Cu46Al8 metallic glasses with pressure preloading was studied by molecular dynamics simulation. As the strain gradually increases, high-density deformation units in different regions are formed in the rejuvenated Zr46Cu46Al8 metallic glass with pressure preloading, but they do not form the shear bands that cause brittle fracture. In terms of the microstructure, the pressure preloading increases the degree of the short range order, but decreases the medium range order. 3-atom connections in the medium range order of icosahedra and other clusters are proposed to represent the level of rejuvenation. The decrease of 3-atom connections in the medium range order can lower the energy barrier and decrease the elastic modulus, improving the level of the rejuvenation. With the weakening of the 3-atom connections, the rejuvenated metallic glass possesses the features of high density, high energy, high Poisson's ratio, high defects and low localization. These findings open an avenue to evaluate the level of rejuvenation and provide a strong foundation for metallic glass design. Keywords: Metallic glass, Rejuvenation, Pressure, Plasticity, Molecular dynamic simulation

Structural and bonding transformation of the Al0.67CrCoFeNi high-entropy alloys (HEA) during quenching is investigated by molecular dynamics simulations. At a high cooling rate, some short-ranged ordered clusters, such as FCC, HCP and BCC crystalline clusters are already present in the almost amorphous HEAs. When the cooling rate decreases, the atoms become packed more orderly and ultimately form a nano-polycrystalline structure dominated by FCC structures. The BCC structures appear only as an intermediate state acting on the course of crystallization, while the HCP structure can be viewed as the precursor of the malposed FCC structure due to the identical first neighbor distances. In liquid HEAs, the low-symmetry and low-coordination bond pairs, either transform to high-symmetry and high-coordination 1551 bond pairs, or transform to 1(5,4)41 bond pairs for FCC structure and 1661 bond pairs for an HCP structure, depending on the cooling rates. This study will contribute to a better understanding of the essential phase change in HEAs.

Minor alloying addition of Ag improves the hydrogen storage capacity and reduces the dehydrogenation temperature of the amorphous Mg65Cu25Y10 alloy. Hydrogen storage capacity is increased from 2.1 wt% to 3.2 wt% when substituting Mg by only 1 at% of Ag. After hydrogenation, the amorphous Mg-Cu-Y(-Ag) alloys decompose into two types of sites for hydrogen occupations: i.e. a new amorphous Mg-Cu(-Ag) hydride clusters and YH3 nanocrystals. This study shows a simple method to tailor hydrogen storage properties of amorphous Mg65Cu25Y10 alloy.

The quasi-crystal-forming alloys with adjustable compositions were prepared by element-addition to a pre-existing pure quasi-crystalline system. The protocol alloy Zr40Ti40Ni20 was chosen as the parent alloy, and beryllium was used as the additive element. The quasi-crystal forming ability was found to be enhanced with Be content within a wide composition range of (Zr40Ti40Ni20)100-xBex (0 ≤ x ≤ 16). A maximum size of up to 10 mm in diameter of pure quasi-crystalline rod was attained at a composition of (Zr40Ti40Ni20)84Be16. Structural analyses show that Be-addition continuously reduces the interplanar spacing. The mechanism of the enhanced quasi-crystal forming ability was also discussed.

The atomic dynamics of a Zr50Cu50 metallic glass-forming liquid has been investigated in isothermal compression by using molecular dynamics simulations. It is found that the mean square displacement (MSD) for Zr is unexpectedly larger than that for Cu under super-high pressures. This interesting result challenges our understanding that the Cu atoms are always faster than Zr atoms in normal liquids, suggesting that the atomic dynamics for Zr becomes extraordinary under super-high pressure. We found that the shorter-bonded Zr atoms can be formed under-super high pressure because of the remarkable softness of Zr-Zr bonding ways. Further studies suggest that this special local structure is responsible for the unexpected atomic dynamics of Zr. These results shed light on the understanding of the inimitable dynamics in Zr-based metallic glass-forming liquids under super-high pressure.

The structural evolution of liquid Mg–Al alloys has been investigated with composition variation from pure Mg to Al at 973 K using ab initio molecular dynamics simulation. The local structures are characterized in terms of pair correlation functions, coordinate numbers, and bond pairs. The atomic interactions are evaluated by the electronic structures to reveal the formation mechanism of the liquid structures. As a result of the fact that the formation of Mg–Al bonds is actually restrained by Al–Al bonds with lower energy, the initial local structures around Mg trend to be maintained as the fragments during the structural evolution, and the discrete Al atoms transforms to be segregated around Mg in the composition region from 18.75 to 31.25 at.% Al. Based on these structural characteristics, the liquid structures are modeled as the Al bonded networks surrounding Mg fragments. Further, the dynamical properties are reflected by the self-diffusion coefficients. The results show that the diffusion of Mg atoms is actually limited by Al bonded networks, which confirm the reliability of the model. It is also worth expecting that the structure model may provide a new viewpoint for further study on the complex metallic alloys in solid Mg–Al system.

Athermal quasi-static compressive deformation for a model metallic glass is investigated by molecular dynamics simulations. A new structural parameter, quasi-nearest atom (QNA), is used to characterize local atomic packing of initial structure. We find that regions with higher nonaffine displacement have more atoms with more QNA. The coarse grained number of QNAs exhibits significant spatial heterogeneities and these structural fluctuations show close correlation with the nonaffine displacement. The correlation between the coarse grained number of QNA and nonaffine displacement does not decrease as the strain increases but show the maximum at a certain strain, indicating that strain localized regions are activated individually. Therefore, our results provide a direct evidence of the correlation between atomic structure and deformation in metallic glass.

The mechanism of refinement of eutectic Si with Sb additions in an Al–10 wt.% Si alloy is studied. The increased holding time designates a transition of the eutectic nucleation temperature from a decreased value to an increased one, accompanied by a morphological transformation of eutectic Si from lamellar to a shorter, rod-like shape. By ab initio molecular dynamics simulation, the chemical short-range order of −0.002 demonstrates weak affinity in the Al–Sb pair, which does not favor the existence of AlSb clusters in the melts. Sb–Sb segregation and the Sb–Si repulsive force are revealed, which promote the formation of Al-enriched precursors and the accumulation of Si atoms adjacent to precursors, inducing precursor nucleation. Continuous attachment of precursors and individual Si atoms during Si growth results in the high number-density nano-particles and suppresses the formation of twin grains within eutectic Si. Keywords: Al–Si alloys, High number-density nano-particle, Precursor-assisted nucleation, Atomic structure, Eutectic Si refinement

The icosahedral short-range order and medium-range order of Zr50Cu50 and Zr50Cu40Al10 metallic glasses have been investigated by molecular dynamics simulations. Our analysis shows that, although the replacement of a few percent of Cu by Al enlarges the population of full icosahedra (FIs), the degree of interpenetrating aggregation for FIs is reduced which might be caused by the strong avoidance of Al-centered FIs in the ternary system. However, this fact does not mean the weakness of icosahedral medium range order in Zr50Cu40Al10 metallic glass. If the interpenetrating and non-interpenetrating connections are both considered, the largest super-cluster formed by the connected FIs in Zr50Cu40Al10 is rather larger than that in Zr50Cu50, which might play an important role in slowing down the kinetics and thus enlarge the glass-forming ability.

The exploration of favourable hydrogen storage materials is of great importance for the realization of a sustainable hydrogen energy society. Here, we report a hydrogen-induced glass-to-glass transition in Mg-based metallic glasses (MGs) with a storage capacity as high as 5 wt%-H. The hydrogen storage capacity of metallic glassy hydrides (MGHs) is obviously higher than that of their crystalline counterparts owing to the free volume and disordered atomic structure associated with glasses. The glass-to-glass transition is demonstrated by direct experimental observation using aberration-corrected scanning transmission electron microscopy combined with ab initio molecular dynamics simulations. Remarkably, the dehydrogenation temperature of the MGHs can be efficiently tuned as it shows a close relationship with the enthalpy of mixing between the alloying element and hydrogen, and can be decreased from ∼350 °C to ∼150 °C when alloying with 5 at.%-Cu. MGs therefore have great potential as solid-state hydrogen storage materials.

Dynamic heterogeneity as one of the most important properties in supercooled liquids has been found for several decades. However, its structural origin remains open for many systems. Here, we propose a new structural parameter to characterize local atomic packing in metallic liquids. It is found that the new parameter in a simulated metallic glass-forming liquid is closely correlated with potential energy and atomic mobility. It also exhibits significant spatial heterogeneities and these structural fluctuations show close correlation with the spatial distribution of the long-time dynamic propensities. Therefore, our results provide a direct evidence of the correlation between atomic structure and dynamical heterogeneity. The new structural parameter might be used to reflect the structural “defect” in metallic liquids and glasses and further play an important role to uncover the structure-property relationship in these disordered systems.

The effects of flow defects of hypothetical metallic glasses on the microstructure and plasticity are investigated through the use of a molecular dynamics simulation. With the design concept of increasing plasticity, the hypothetical metallic glass containing much effective flow defects is successfully simulated by using Zr45Cu45Al10 metallic glass as the precursor. Simulation reproduces the images depicting the microstructural evolution after yielding the required flow defects. This model analysis quantitatively demonstrates that the yielding flow defects render hypothetical metallic glasses closer to their liquid structure. The flow defects lead to only small reductions in strength, but to a significantly enhanced plasticity. The simulation results are in good agreement with those obtained by experiment. These findings provide physical insight into the mechanical instability and provide a strong foundation for future metallic glass designs.

The structures of liquid Fe–C alloys in the Fe-rich end were investigated by ab initio molecular dynamics simulations. The trend of intensity of chemical short range order around Fe and C atoms changes at the eutectic composition, indicating the close correlation between liquid structure and phase diagram. The tri-capped trigonal prism (Voronoi index ) and mono-capped square archimedean antiprism (Voronoi index ) around C atoms have the largest frequency fractions and the longest lifetimes among all the polyhedra. Moreover, they tend to connect with each other to form network structure. The maximum intensity of network structure is located at the 20% C composition, which might be the reason why alloys near eutectic composition have great glass-forming ability.

The effect of Y minor addition on the structure-property relationship of Mg65Cu25Y10 metallic glass was investigated through molecular dynamics simulations. The average local five-fold symmetry is reduced and the number of quasi-nearest atoms increases in Mg65Cu25Y10, indicating a lower atomic packing. This fact is inconsistent to the normal effect of minor elements to enhance the glass-forming ability by enlarging the atomic packing of the systems. Although the reduce of atomic packing, the numbers of icosahedra and some other Kasper polyhedra with the fewest disclinations increase in Mg65Cu25Y10. That might be the reason for the larger glass forming ability of Mg65Cu25Y10 than Mg65Cu35. Moreover, the strength of Mg65Cu25Y10 is not weakened by the low atomic packing, which might result from the strong chemical bonding of Cu-Y. Our results are helpful to understand the effect of minor elements on the properties of metallic glasses.

Molecular dynamics simulations on the atomic structure of shear bands (SBs) in Cu64Zr36 metallic glasses are presented. Results show that the atoms in the SB move desultorily, in contrast to those in the matrix. The saturated degree of bonded pairs considering the “liquid-like” character of SB quantitatively provides important details in extending earlier studies on SBs. Zr-centered 〈0, 2, 8, 5〉 clusters exhibit strong spatial correlations and tendency to connect with each other in short-range order. The 〈0, 2, 8, 5〉 cluster-type medium-range order is the main feature inside the SB relative to the matrix. The fractal results demonstrate the planar-like fashion of the 〈0, 2, 8, 5〉 network in SB, forming an interpenetrating solid-like backbone. Such heterogeneous structure provides a fundamental structural perspective of mechanical instability in SB.

In many glass-forming liquids, fractional Stokes-Einstein relation (SER) is observed above the glass transition temperature. However, the origin of such phenomenon remains elusive. Using molecular dynamics simulations, we investigate the break- down of SER and the onset of fractional SER in a model of metallic glass-forming liquid. We find that SER breaks down when the size of the largest cluster consisting of trapped atoms starts to increase sharply at which the largest cluster spans half of the simulations box along one direction, and the fractional SER starts to follows when the largest cluster percolates the entire system and forms 3-dimentional network structures. Further analysis based on the percolation theory also confirms that percolation occurs at the onset of the fractional SER. Our results directly link the breakdown of the SER with structure inhomogeneity and onset of the fraction SER with percolation of largest clusters, thus provide a possible picture for the break- down of SER and onset of fractional SER in glass-forming liquids, which is is important for the understanding of the dynamic properties in glass-forming liquids.

Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously.

The deformation behaviors of body-centered cubic Cu 0.5 CoNiCrAl high-entropy alloys processed by the cooling rate gradient are investigated by the molecular dynamics simulations. The plastic deformation ability of the high-entropy alloy is significantly improved by triggering multiple-type dislocation slips along different deformation paths. The cooling rate gradient introduces abundant atomic vacancies, proliferating the nucleation sites of dislocations. Additionally, the nucleation barriers of dislocations are reduced by the resultant structural disorder, high potential energy and chemical segregation. Consequently, the cooling rate gradient enhances the structural heterogeneity, promoting the formation of multiple deformation paths and preventing strain localization.

To clarify the relation between the thermodynamics and metastable pitting behavior of Al–Ni–Gd glassy alloys, the as-spun ribbons were investigated using various experimental methods and ab initio molecular dynamic simulations. The results show that the relative area of main peak shoulder in XRD patterns, onset crystallization temperature, contraction degree of samples increase with increasing c Ni . The peak for the metastable pitting events in the polarization curves with Cl − containing solutions is accelerated by increasing c Ni . The variation of thermal and electrochemical properties of samples is attributed to the strong interaction of Al–Ni bond based on the atomic structure analysis.

We investigated structural disorder by a new structural parameter, quasi-nearest atom (QNA), in atomistic configurations of eight metallic glass-forming systems generated through molecular dynamics simulations at various temperatures. Structural analysis reveals that the scaled distribution of the number of QNA appears to be an universal property of metallic liquids and the spatial distribution of the number of QNA displays to be clearly heterogeneous. Furthermore, the new parameter can be directly correlated with potential energy and structural relaxation at the atomic level. Some straightforward relationships between QNA and other properties (per-atom potential energy and α-relaxation time) are introduced to reflect structure-property relationship in metallic liquids. We believe that the new structural parameter can well reflect structure disorder in metallic liquids and play an important role in understanding various properties in metallic liquids.

The liquid structure of Zn95Fe5 alloy was studied by ab initio molecular dynamic simulations. The important variation tendency of pair correlation function has been characterized. It is found that the interaction of unlike atoms is stronger than the like atoms. Voronoi polyhedron analysis reveals that icosahedral-like clusters are frequently found around Fe and the dominated voronoi polyhedrons around Zn atoms are icosahedral-like and deformed-bcc clusters. Chemical short range order analysis suggests that there are 12 Zn atoms around Fe, which is similar to the structure of FeZn13 phase. More importantly, this simulated result is proved indirectly by the experiment that a mass of FeZn13 phase was confirmed in zinc slag by X-ray diffraction, which indicates that the liquid structure is partially kept during solidification process.

We report simulations on the local structural evolution in the liquid-bcc transition of a model iron. Fourteen main Voronoi polyhedra are chosen as the representatives of short-range orders (SROs) and their transformations during crystallization are also investigated. Thus, the crystallization pathways for the main SROs are drawn. Our results also show that the transformations between two SROs in the crystallization pathways can be classified into two categories, first the enlargement of coordination number, second the transformation of local symmetry from five-fold to four-fold. The former reduces the potential energy while the latter increases it. It is found that the potential energy cannot decease monotonously whatever crystallization pathway is chosen to transform the icosahedral SRO to bcc SRO. Therefore, the latter transformation might provide the energy barrier of crystallization. We propose two transformation styles among SROs. All the transformations in the crystallization pathways can be achieved according to the styles. Moreover, the two transformation styles indicates that the bcc structure is more similar to liquid than other crystals. That might be the reason why the first phase nucleated during a rapid cooling process should be bcc crystal.

The structure of Fe 80 Si 10 B 10 alloy melt was investigated by ab initio molecular dynamic simulation from the local atomic environments. It presents that Fe 80 Si 10 B 10 alloy can be considered as the combination of B-centered prism-like clusters and bcc-like Fe-Si solid solution. The poor glass-forming ability of the alloy has been investigated and can be attributed to the bcc-like environment around Si atoms and the relative high content of pure Fe clusters.