Recently we have reported a number of bulk glass forming compositions in the CuHf-Ti system,with the critical thickness for complete glass formation,dc,ranging from 2 mm to 4 mm.In order to improve the glass forming a...Recently we have reported a number of bulk glass forming compositions in the CuHf-Ti system,with the critical thickness for complete glass formation,dc,ranging from 2 mm to 4 mm.In order to improve the glass forming ability （GFA） getting even larger dc,the prevailing approach is to use complex multicomponent systems.This strategy has been investigated by us for the Cu-Hf-Ti bulk glass forming alloy Cu55Hf25Ti20 using 〉1 at.pct additions of B,Y,Nb,Ta,Al,Mn,Si or V but with no significant improvement in the GFA.Clearly,it is necessary,in order to utilise the full potential of the base ternary system,to identify the best glass-forming compositions as a basis for extending the search into multi-dimensional compositional space.Thus,CuxHfyTiz alloys,where x=（40-70） at.pct,y=（5-30） at.pct,and z=（10-36） at.pct,were prepared by melt spinning andcopper mould suction-casting.The composition dependence of the GFA for the Cu-Hf-Ti alloys,as measured by dc for rod and ribbon samples,is reported over the composition range given above.展开更多
The glass forming ability, thermal and mechanical properties of some Zr Cu Al Ni bulk metallic glasses were analyzed. The compositions of the alloys were theoretically determined with the dense packing and kinetic fra...The glass forming ability, thermal and mechanical properties of some Zr Cu Al Ni bulk metallic glasses were analyzed. The compositions of the alloys were theoretically determined with the dense packing and kinetic fragility index models. Cylindrical and conical ingots were produced by copper mould suction-casting under Ar atmosphere. The conical ingots were characterized by means of X-ray diffraction in order to determine the glassy structure. It was found that both alloys have a critical glassy diameter, Dc, of 3 mm. Thermal behaviours were investigated by differential scanning calorimetry at heating rates of 0.5, 0.67 and 0.83 K/s. The gamma parameter γ, supercooled liquid region ΔTx, and reduced glass transition temperature Trg, of the experimentally obtained glasses indicated high glass forming ability. The glassy compositions showed a fragility index of ~40 GPa. The compression test of the investigated alloys was carried out at a strain rate of 0.016 s^-1, obtaining a elastic modulus of ~83 GPa, total deformation of ~5%, yield strength of 1.6 GPa and hardness of 4 GPa. It was concluded that the use of the dense packing and kinetic fragility index models helped to predict glass-forming compositions in the family alloy investigated.展开更多
The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, an...The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, and the refractive indexes and absorption spectra of samples were measured. It is found that the refractive index of samples as well as the UV absorption increase with the increase of BaO content. According to the Tauc law, optical band gap Eopg which is assumed to be the effective energy band gap Eg is calculated and decreases with the increasing BaO content, and the ratio of Eg/Eopg is 1.3.展开更多
In this paper the critical cooling rate, Rc, for the glass formation of Fe80P13C7 alloy has been determined using both Uhlmann＇s and Barandiaran-Colmenero＇s method. In Uhlmann＇s method, all kinds of the expres-sion...In this paper the critical cooling rate, Rc, for the glass formation of Fe80P13C7 alloy has been determined using both Uhlmann＇s and Barandiaran-Colmenero＇s method. In Uhlmann＇s method, all kinds of the expres-sions of △G^l-s （T） and η/（T） determined using the different modes and methods had been investigated. It is indicated that the Rc for the glass formation of FesoP13C7 alloy can be estimated to be 349 K/s by Uhlmann＇s method based on the appropriate expressions of △G^l-s（T） and η/（T）. The calculated result accords with our experimental result. The Rc for the glass formation of Fe80P13C7 alloy has also been determined to be 0.49 K/s using Barandiaran-Colmenero＇s method. This resultant Rc is unreasonable low and it indicates that Barandiaran-Colmenero＇s method does not suit to Fe-based alloy.展开更多
The dynamics of polymeric and other glass-forming liquids dramatically slows down upon cooling toward the glass transition temperature without any obvious significant change in their static structure.A quantitative un...The dynamics of polymeric and other glass-forming liquids dramatically slows down upon cooling toward the glass transition temperature without any obvious significant change in their static structure.A quantitative understanding of this extraordinary dynamic slowdown remains one of the most significant challenges in condensed matter physics.Historically,extensive efforts have been devoted to explaining the dynamics of glass-forming liquids in terms of thermodynamic properties,leading to a number of semi-empirical models emphasizing distinct thermodynamic properties.Here,a thermodynamic perspective is provided on the glass formation of polymeric and other materials.We begin with an overview of the thermodynamic models of glass formation,including the intuitively appealing“free volume”models,enthalpy models originally emphasized by Goldstein and later by others,and the highly influential configurational entropy-based models.The review of these models is followed by a discussion of the advances that attempt to bring together some of the seemingly disparate thermodynamic viewpoints on glass formation by revealing a close interrelation between thermodynamic properties.We conclude this review with remarks on several key topics in this field,along with our viewpoint for future work.展开更多
Having highly tunable molecular topology is one of the most important characteristics of polymers that provides these materials with a wide range of interesting and unique properties.In particular,ring polymers exhibi...Having highly tunable molecular topology is one of the most important characteristics of polymers that provides these materials with a wide range of interesting and unique properties.In particular,ring polymers exhibit a number of properties that are markedly distinct from their linear counterparts.Here,we compare and contrast the glass formation of unknotted,nonconcatenated ring and linear polymer melts having variable molecular mass based on molecular dynamics simulations of a coarse-grained model.After revealing an unusual property in the structure of small rings,we discuss the mass dependence of the structural relaxation time determined from the self-intermediate scattering function over a wide range of temperatures in both ring and linear polymers.As a general trend,we find that the characteristic temperatures(e.g.,the glass transition temperature)and fragility of glass formation increase with increasing molecular mass in linear polymers,but the mass dependences of these properties are rather weak in the family of ring polymer models considered,in broad accord with experimental measurements.Importantly,we show that the glass formation of ring polymers can quantitatively be described by the string model,a model that is broadly consistent with the entropy theory of glass formation and that takes the mass of string-like clusters as a molecular realization of the abstract cooperatively rearranging regions.This opens the possibility of applying the configurational entropy-based theories to describe the glass formation of ring polymers,once the ring topology is taken into account.展开更多
In this paper the characteristics of glass formation and structure of non-oxide glasses, have been summarized and some basic points have been discussed. The main points are as follows-Chemical bond nature is a deter-m...In this paper the characteristics of glass formation and structure of non-oxide glasses, have been summarized and some basic points have been discussed. The main points are as follows-Chemical bond nature is a deter-minative factor of formation and structure of glass ;Calcu-lation of glass formation ability by chemical bond paramiters; Classification of inorganic glass systems by characteristics of short range order of the glass structure; Structural models of non-oxide glasses.展开更多
Using coarse-grained molecular dynamics simulations based on Gay-Berne potential model, we have simulated the cooling process of liquid n-butanol. A new set of GB parameters are obtained by fitting the results of dens...Using coarse-grained molecular dynamics simulations based on Gay-Berne potential model, we have simulated the cooling process of liquid n-butanol. A new set of GB parameters are obtained by fitting the results of density functional theory calculations. The simulations are carried out in the range of 290-50 K with temperature decrements of 10 K. The cooling characteristics are determined on the basis of the variations of the density, the potential energy and orientational order parameter with temperature, whose slopes all show discontinuity. Both the radial distribution function curves and the second-rank orientational correlation function curves exhibit splitting in the second peak. Using the discontinuous change of these thermodynamic and structure properties, we obtain the glass transition at an estimate of temperature Tg=1204.10 K, which is in good agreement with experimental results 1104-1 K.展开更多
Dual-nano-phase alloys with an ultrafine crystal-glass imbedding nanostructure exhibit exceptional high structural and functional performances,yet they generally suffer from the dimension limit and the harsh manufactu...Dual-nano-phase alloys with an ultrafine crystal-glass imbedding nanostructure exhibit exceptional high structural and functional performances,yet they generally suffer from the dimension limit and the harsh manufacturing process,especially for the one with a simple nanocrystalline phase comprised of the principal component.Here,an innovative composition design strategy was developed to unprecedentedly combine the high glass-forming andα-Fe nanocrystallizing abilities in Febased alloys,via kinetic ally slowing the devitrification process and thermodynamically facilitating theα-Fe nanocrystallization.The newly developed(Fe_(71)Nb_(6))_(x/77)B_(100-x)alloys exhibit a high glass-forming ability(critical dimension of 1 mm)for fast solidification productions of glassy precursors and a large temperature interval for the nanoprecipitation,meeting the requirements of multiple industrialization techniques.Moreover,the alloys possess attractive soft magnetic properties in multi-states,overcoming the common problems of the grain coarsening and property fluctuation.These are of paramount importance for the widespread applications of the emerging materials,and can mechanistically reveal the intrinsic connection between the glass formation and nanocrystallization.展开更多
A series of new glass compositions based on PbX2 (X: Cl, Br or I) have been studied. Binary and ternary glasses resulted from the association of PbI2, Pb-Cl-2, AgI, KCl and KBr. By means of differential scanning calor...A series of new glass compositions based on PbX2 (X: Cl, Br or I) have been studied. Binary and ternary glasses resulted from the association of PbI2, Pb-Cl-2, AgI, KCl and KBr. By means of differential scanning calorimetry (DSC), the mechanism and kinetics of crystallization process were studied. X-ray diffraction studies demonstrate that there is the formation of complicated crystalline phases in crystallized lead iodide based glasses. By heat treating halide glasses of appropriate composition under adequate heating temperature and duration, the lead iodide based glasses could be converted into glass-ceramics with microcrystal size less 1 mu m of which mechanical properties are improved.展开更多
Development of advanced metals materials with ultrahigh strength,large plasticity and high thermostability is one of the most attractive aims for materials researchers.Co-based bulk metallic glasses(BMGs)with the high...Development of advanced metals materials with ultrahigh strength,large plasticity and high thermostability is one of the most attractive aims for materials researchers.Co-based bulk metallic glasses(BMGs)with the highest strength(up to 6 GPa)and special strength(up to 650 Nm/g)among all of metals materials so far we known have received extensive attentions.In this paper,a family of Co-Ta-B-Si BMGs with high glass-transition temperature(above 870 K),large compressive plasticity(up to 6.4%)and high strength(above 5.5 GPa),and high glass-forming ability(the critical diameter,Dc:up to 4 mm)was developed by accurately tuning metalloid element contents of Si and B in the parental alloy of Co_(55)Ta_(10)B_(35).The changes of glass formation and plasticity caused by the adjustment of the constituent metalloid elements were evaluated by the combination of experimental and calculated results.The reason for the significant improvement of plastic deformation is revealed by the analysis of the self-organization behaviors of high-density shear bands.展开更多
Inspired by research into the association between icosahedral local orders and the plasticity of metallic glasses(MGs),beryllium(Be) is added to the icosahedral quasi-crystal forming alloy Zr40Ti40Ni20. In this way, b...Inspired by research into the association between icosahedral local orders and the plasticity of metallic glasses(MGs),beryllium(Be) is added to the icosahedral quasi-crystal forming alloy Zr40Ti40Ni20. In this way, bulk metallic glasses(BMGs) with favorable compressive plasticity are fabricated. Therein, the icosahedral quasi-crystalline phase is the main competing phase of amorphous phases and icosahedral local orders are the main local atomic motifs in amorphous phases.The alloys of(Zr40Ti40Ni20)76Be24and (Zr40Ti40Ni20)72Be28with their greater plastic strain capacity show similar characteristics to highly plastic amorphous systems: The serrated flow of compression curves always follows a near-exponential distribution. The primary and secondary shear bands intersect each other, bifurcate, and bend. Typical vein patterns are densely distributed on the fracture surfaces. The relaxation enthalpy of four MGs is linearly correlated with the plastic strain, that is, the greater the relaxation enthalpy, the larger the plastic strain.展开更多
This paper reports the formation and some properties of a new class of chalcohalide glasses in the As2Tef iodide systems. The As2Te3-Pb12, As2Te3-HgI2, As2Te3-CitI and As2Te3-AgI systems can form stable bulk glasses i...This paper reports the formation and some properties of a new class of chalcohalide glasses in the As2Tef iodide systems. The As2Te3-Pb12, As2Te3-HgI2, As2Te3-CitI and As2Te3-AgI systems can form stable bulk glasses in wide composition regions ?and no bulk glass formation was found in the As2Te3-TH sys-tem. As2Te3-based glasses have glass transition tempera-展开更多
The fundamental science behind glass and glass-ceramics in relation to research including syntheses, processing, characterization and applications are critically reviewed in this paper. The crystalline structure of th...The fundamental science behind glass and glass-ceramics in relation to research including syntheses, processing, characterization and applications are critically reviewed in this paper. The crystalline structure of the crystalline phases/s investigated in the literature is also discussed. Throughout this paper, the scene is set toward the overall picture of the rationale behind the choice of a glass system. Additionally, earlier reviews do not include the most recent literature in this fast-moving field. The main methods of synthesizing glasses and glass-ceramics are explained and described in relation to their applications. The paper concludes with recommendations for future research.展开更多
This work investigated the microstructure,magnetic properties,and crystallization kinetics of the as-spun and annealed alloy ribbons of(Fe_(40-x)Co_xNi_(40)Si_(6.33)B_(12.66)Cu_1)_(0.97)Nb_(0.03),where x=0,6,7,8,9,pre...This work investigated the microstructure,magnetic properties,and crystallization kinetics of the as-spun and annealed alloy ribbons of(Fe_(40-x)Co_xNi_(40)Si_(6.33)B_(12.66)Cu_1)_(0.97)Nb_(0.03),where x=0,6,7,8,9,prepared using the meltspinning method.The results show that adding a moderate amount of Co can improve the glass forming ability(GFA),the first peak crystallization temperature,and thermal stability of the as-spun alloy ribbons.With x=7,the two-stage crystallization temperature interval△Tx=90 exhibits optimal thermal stability,and the alloy annealed at 673 K for 10 minutes shows the favorable combined magnetic properties,with H_(c)=0.12 A/m,M_(s)=88.7 A·m^(2)/kg,andμ_(e)=13800.The magnetic domain results show that annealing removes numerous pinning points in the magnetic domains of the alloy ribbons,making the domain walls smoother and effectively reducing the pinning effect.展开更多
The Mg65Cu25Y10 melts were quenched at a temperature of 973 K under various pressures in the range of 2-5 GPa and ambient pressure. The microstructure of the solidified specimens has been investigated by X-ray diffrac...The Mg65Cu25Y10 melts were quenched at a temperature of 973 K under various pressures in the range of 2-5 GPa and ambient pressure. The microstructure of the solidified specimens has been investigated by X-ray diffraction, transmission electron microscope and electron probe microanalysis. Experimental results show that the pressure has a great influence on the solidification microstructure of the Mg65Cu25Y10. At ambient pressure, the solidification products are Mg2(Cu,Y) and a very small amount of Y2O3 inclusion. As the pressure is above 2 GPa, a new Cu2(Y,Mg) phase appears, while Y2O3 is not observed at the pressure of 3, 4 and 5 GPa. When the pressure increases from 2 GPa to 5 GPa, the grain sizes of Mg2(Cu,Y) and Cu2(Y,Mg) decrease from 125, 96 nm to 80, 7 nm, respectively. The mechanisms for the effects of the pressure on the phase evolution and microstructure during solidification process of Mg65Cu25Y10 alloy have been discussed.展开更多
The surface of Ni_（61）Nb_（39） crystalline ingot was treated by laser surface melting with different processing parameters.A fully amorphous layer with a thickness of approximately 10μm could be produced on the to...The surface of Ni_（61）Nb_（39） crystalline ingot was treated by laser surface melting with different processing parameters.A fully amorphous layer with a thickness of approximately 10μm could be produced on the top surface under optimal parameters.An amorphous-crystalline composite layer with the depth from 10 to 50μm,consisting of amorphous matrix and intermetallic phases of Ni_3 Nb and Ni_6Nb_7,could be formed.The micro-hardness（about 831HV）of the treated surface was remarkably improved by nearly 100% compared with the value of the crystalline substrate caused by the formation of the fully amorphous structure.A finite volume simulation was adopted to evaluate the temperature distribution in the laser-affected zone of Ni_（61）Nb_（39） alloys and to reveal the mechanism of glass formation in the laser-affected zone.展开更多
Advances in developing high entropy alloys and ceramics with improved physical properties have greatly broadened their application field from aerospace industry,public transportation to nuclear plants.In this review,w...Advances in developing high entropy alloys and ceramics with improved physical properties have greatly broadened their application field from aerospace industry,public transportation to nuclear plants.In this review,we describe the concept of entropy engineering as applicable to inorganic non-metallic glasses,especially for tailoring and enhancing their mechanical,electrical,and optical properties.We also present opportunities and challenges in calculating entropy of inorganic non-metallic glass systems,correlating entropy to glass formation,and in developing functional inorganic non-metallic glasses via the entropy concept.展开更多
Ab-initio molecular dynamics simulation was performed to investigate the local atomic structure of Co55Ta^0B35 alloys. Pair distribution function, coordination number, HA index and Voronoi polyhedra were used to descr...Ab-initio molecular dynamics simulation was performed to investigate the local atomic structure of Co55Ta^0B35 alloys. Pair distribution function, coordination number, HA index and Voronoi polyhedra were used to describe the detailed local structure of this alloy. It was revealed Co7TalB2, Co6TalB2 and CosTa2B4 among the dominant （0 3 6 0）, （0 4 4 0）, （0 1 10 2） and （0 3 6 4） polyhedra were the basic local structure units in CossTal0B3s amorphous alloy. Furthermore, most of the dominant poly- hedra tended to have Ta atoms involved and these polyhedra may have a critical role during glass formation.展开更多
基金support of PAPIIT-UNAM IB100712SENER-CONACYT151496 in funding the project
文摘Recently we have reported a number of bulk glass forming compositions in the CuHf-Ti system,with the critical thickness for complete glass formation,dc,ranging from 2 mm to 4 mm.In order to improve the glass forming ability （GFA） getting even larger dc,the prevailing approach is to use complex multicomponent systems.This strategy has been investigated by us for the Cu-Hf-Ti bulk glass forming alloy Cu55Hf25Ti20 using 〉1 at.pct additions of B,Y,Nb,Ta,Al,Mn,Si or V but with no significant improvement in the GFA.Clearly,it is necessary,in order to utilise the full potential of the base ternary system,to identify the best glass-forming compositions as a basis for extending the search into multi-dimensional compositional space.Thus,CuxHfyTiz alloys,where x=（40-70） at.pct,y=（5-30） at.pct,and z=（10-36） at.pct,were prepared by melt spinning andcopper mould suction-casting.The composition dependence of the GFA for the Cu-Hf-Ti alloys,as measured by dc for rod and ribbon samples,is reported over the composition range given above.
基金the financial support from UNAM-DGAPA-PAPIIT thorough the project 101016CONACYT for the 232312 Ph D scholarship grant
文摘The glass forming ability, thermal and mechanical properties of some Zr Cu Al Ni bulk metallic glasses were analyzed. The compositions of the alloys were theoretically determined with the dense packing and kinetic fragility index models. Cylindrical and conical ingots were produced by copper mould suction-casting under Ar atmosphere. The conical ingots were characterized by means of X-ray diffraction in order to determine the glassy structure. It was found that both alloys have a critical glassy diameter, Dc, of 3 mm. Thermal behaviours were investigated by differential scanning calorimetry at heating rates of 0.5, 0.67 and 0.83 K/s. The gamma parameter γ, supercooled liquid region ΔTx, and reduced glass transition temperature Trg, of the experimentally obtained glasses indicated high glass forming ability. The glassy compositions showed a fragility index of ~40 GPa. The compression test of the investigated alloys was carried out at a strain rate of 0.016 s^-1, obtaining a elastic modulus of ~83 GPa, total deformation of ~5%, yield strength of 1.6 GPa and hardness of 4 GPa. It was concluded that the use of the dense packing and kinetic fragility index models helped to predict glass-forming compositions in the family alloy investigated.
基金Funded by the National Natural Science Foundation of China (No.60677015)the Tackling Key Project of Science and Technology Department of Zhejiang Province (No. 2007C21122)+1 种基金the Natural Science Foundation of Ningbo (No. 2006A610020)sponsored by K C Wong Magna Fund in NingBo University
文摘The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, and the refractive indexes and absorption spectra of samples were measured. It is found that the refractive index of samples as well as the UV absorption increase with the increase of BaO content. According to the Tauc law, optical band gap Eopg which is assumed to be the effective energy band gap Eg is calculated and decreases with the increasing BaO content, and the ratio of Eg/Eopg is 1.3.
基金supported by the National Natural Science Foundation of China (No. 50861007)the Project of Supporting Xinjiang Uyghur Autonomous Region by Science and Technology (No. 201191203)the Opening Subject from State Key Laboratory of Powder Metallurgy in Central South University
文摘In this paper the critical cooling rate, Rc, for the glass formation of Fe80P13C7 alloy has been determined using both Uhlmann＇s and Barandiaran-Colmenero＇s method. In Uhlmann＇s method, all kinds of the expres-sions of △G^l-s （T） and η/（T） determined using the different modes and methods had been investigated. It is indicated that the Rc for the glass formation of FesoP13C7 alloy can be estimated to be 349 K/s by Uhlmann＇s method based on the appropriate expressions of △G^l-s（T） and η/（T）. The calculated result accords with our experimental result. The Rc for the glass formation of Fe80P13C7 alloy has also been determined to be 0.49 K/s using Barandiaran-Colmenero＇s method. This resultant Rc is unreasonable low and it indicates that Barandiaran-Colmenero＇s method does not suit to Fe-based alloy.
基金support from the National Natural Science Foundation of China(Nos.22222307 and 21973089)support from the National Natural Science Foundation of China(Nos.21833008 and 52293471)the National Key R&D Program of China(No.2022YFB3707303)。
文摘The dynamics of polymeric and other glass-forming liquids dramatically slows down upon cooling toward the glass transition temperature without any obvious significant change in their static structure.A quantitative understanding of this extraordinary dynamic slowdown remains one of the most significant challenges in condensed matter physics.Historically,extensive efforts have been devoted to explaining the dynamics of glass-forming liquids in terms of thermodynamic properties,leading to a number of semi-empirical models emphasizing distinct thermodynamic properties.Here,a thermodynamic perspective is provided on the glass formation of polymeric and other materials.We begin with an overview of the thermodynamic models of glass formation,including the intuitively appealing“free volume”models,enthalpy models originally emphasized by Goldstein and later by others,and the highly influential configurational entropy-based models.The review of these models is followed by a discussion of the advances that attempt to bring together some of the seemingly disparate thermodynamic viewpoints on glass formation by revealing a close interrelation between thermodynamic properties.We conclude this review with remarks on several key topics in this field,along with our viewpoint for future work.
基金financially supported by the National Natural Science Foundation of China(Nos.22222307 and 21973089)。
文摘Having highly tunable molecular topology is one of the most important characteristics of polymers that provides these materials with a wide range of interesting and unique properties.In particular,ring polymers exhibit a number of properties that are markedly distinct from their linear counterparts.Here,we compare and contrast the glass formation of unknotted,nonconcatenated ring and linear polymer melts having variable molecular mass based on molecular dynamics simulations of a coarse-grained model.After revealing an unusual property in the structure of small rings,we discuss the mass dependence of the structural relaxation time determined from the self-intermediate scattering function over a wide range of temperatures in both ring and linear polymers.As a general trend,we find that the characteristic temperatures(e.g.,the glass transition temperature)and fragility of glass formation increase with increasing molecular mass in linear polymers,but the mass dependences of these properties are rather weak in the family of ring polymer models considered,in broad accord with experimental measurements.Importantly,we show that the glass formation of ring polymers can quantitatively be described by the string model,a model that is broadly consistent with the entropy theory of glass formation and that takes the mass of string-like clusters as a molecular realization of the abstract cooperatively rearranging regions.This opens the possibility of applying the configurational entropy-based theories to describe the glass formation of ring polymers,once the ring topology is taken into account.
文摘In this paper the characteristics of glass formation and structure of non-oxide glasses, have been summarized and some basic points have been discussed. The main points are as follows-Chemical bond nature is a deter-minative factor of formation and structure of glass ;Calcu-lation of glass formation ability by chemical bond paramiters; Classification of inorganic glass systems by characteristics of short range order of the glass structure; Structural models of non-oxide glasses.
文摘Using coarse-grained molecular dynamics simulations based on Gay-Berne potential model, we have simulated the cooling process of liquid n-butanol. A new set of GB parameters are obtained by fitting the results of density functional theory calculations. The simulations are carried out in the range of 290-50 K with temperature decrements of 10 K. The cooling characteristics are determined on the basis of the variations of the density, the potential energy and orientational order parameter with temperature, whose slopes all show discontinuity. Both the radial distribution function curves and the second-rank orientational correlation function curves exhibit splitting in the second peak. Using the discontinuous change of these thermodynamic and structure properties, we obtain the glass transition at an estimate of temperature Tg=1204.10 K, which is in good agreement with experimental results 1104-1 K.
基金financially supported by the National Key R&D Program of China(No.2023YFB3711900)the National Natural Science Foundation of China(Nos.52271143,52001184 and 52201175)
文摘Dual-nano-phase alloys with an ultrafine crystal-glass imbedding nanostructure exhibit exceptional high structural and functional performances,yet they generally suffer from the dimension limit and the harsh manufacturing process,especially for the one with a simple nanocrystalline phase comprised of the principal component.Here,an innovative composition design strategy was developed to unprecedentedly combine the high glass-forming andα-Fe nanocrystallizing abilities in Febased alloys,via kinetic ally slowing the devitrification process and thermodynamically facilitating theα-Fe nanocrystallization.The newly developed(Fe_(71)Nb_(6))_(x/77)B_(100-x)alloys exhibit a high glass-forming ability(critical dimension of 1 mm)for fast solidification productions of glassy precursors and a large temperature interval for the nanoprecipitation,meeting the requirements of multiple industrialization techniques.Moreover,the alloys possess attractive soft magnetic properties in multi-states,overcoming the common problems of the grain coarsening and property fluctuation.These are of paramount importance for the widespread applications of the emerging materials,and can mechanistically reveal the intrinsic connection between the glass formation and nanocrystallization.
基金This project was supported by the National Natural Science Foundation of China and the Foundation of the State Commission of Education
文摘A series of new glass compositions based on PbX2 (X: Cl, Br or I) have been studied. Binary and ternary glasses resulted from the association of PbI2, Pb-Cl-2, AgI, KCl and KBr. By means of differential scanning calorimetry (DSC), the mechanism and kinetics of crystallization process were studied. X-ray diffraction studies demonstrate that there is the formation of complicated crystalline phases in crystallized lead iodide based glasses. By heat treating halide glasses of appropriate composition under adequate heating temperature and duration, the lead iodide based glasses could be converted into glass-ceramics with microcrystal size less 1 mu m of which mechanical properties are improved.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0703601)the National Natural Science Foundation of China(Grant Nos.51771008)Beijing Natural Science Foundation(2172034)。
文摘Development of advanced metals materials with ultrahigh strength,large plasticity and high thermostability is one of the most attractive aims for materials researchers.Co-based bulk metallic glasses(BMGs)with the highest strength(up to 6 GPa)and special strength(up to 650 Nm/g)among all of metals materials so far we known have received extensive attentions.In this paper,a family of Co-Ta-B-Si BMGs with high glass-transition temperature(above 870 K),large compressive plasticity(up to 6.4%)and high strength(above 5.5 GPa),and high glass-forming ability(the critical diameter,Dc:up to 4 mm)was developed by accurately tuning metalloid element contents of Si and B in the parental alloy of Co_(55)Ta_(10)B_(35).The changes of glass formation and plasticity caused by the adjustment of the constituent metalloid elements were evaluated by the combination of experimental and calculated results.The reason for the significant improvement of plastic deformation is revealed by the analysis of the self-organization behaviors of high-density shear bands.
基金supported by the National Key R&D Program of China (Grant No. 2018YFA0703602)the National Natural Science Foundation of China (Grant Nos. 51871193, 52271155 and 52271154)+2 种基金the Natural Science Foundation for Excellent Young Scholars of Hebei Province (Grant No. E2021203050)the Hundred Talent Program of Hebei Province (Grant No. E2020050018)the Hebei Province Innovation Ability Promotion Project (Grant No. 22567609H)。
文摘Inspired by research into the association between icosahedral local orders and the plasticity of metallic glasses(MGs),beryllium(Be) is added to the icosahedral quasi-crystal forming alloy Zr40Ti40Ni20. In this way, bulk metallic glasses(BMGs) with favorable compressive plasticity are fabricated. Therein, the icosahedral quasi-crystalline phase is the main competing phase of amorphous phases and icosahedral local orders are the main local atomic motifs in amorphous phases.The alloys of(Zr40Ti40Ni20)76Be24and (Zr40Ti40Ni20)72Be28with their greater plastic strain capacity show similar characteristics to highly plastic amorphous systems: The serrated flow of compression curves always follows a near-exponential distribution. The primary and secondary shear bands intersect each other, bifurcate, and bend. Typical vein patterns are densely distributed on the fracture surfaces. The relaxation enthalpy of four MGs is linearly correlated with the plastic strain, that is, the greater the relaxation enthalpy, the larger the plastic strain.
文摘This paper reports the formation and some properties of a new class of chalcohalide glasses in the As2Tef iodide systems. The As2Te3-Pb12, As2Te3-HgI2, As2Te3-CitI and As2Te3-AgI systems can form stable bulk glasses in wide composition regions ?and no bulk glass formation was found in the As2Te3-TH sys-tem. As2Te3-based glasses have glass transition tempera-
文摘The fundamental science behind glass and glass-ceramics in relation to research including syntheses, processing, characterization and applications are critically reviewed in this paper. The crystalline structure of the crystalline phases/s investigated in the literature is also discussed. Throughout this paper, the scene is set toward the overall picture of the rationale behind the choice of a glass system. Additionally, earlier reviews do not include the most recent literature in this fast-moving field. The main methods of synthesizing glasses and glass-ceramics are explained and described in relation to their applications. The paper concludes with recommendations for future research.
基金Project supported by the National Natural Science Foundation of China(Grant No.52275567)the Key Research and Development Program of Shanxi Province,China(Grant No.202202050201020)+3 种基金the Doctoral Starting-up Foundation of Taiyuan University of Science and Technology(Grant No.20192016)the Research Project Supported by Shanxi Scholarship Council(Grant No.2017-085)the Graduate Education and Teaching Reform Project of Shanxi Province,China(Grant No.2023JG136)the Special Fund for Science and Technology Innovation Teams of Shanxi Province,China(Grant No.202304051001036)。
文摘This work investigated the microstructure,magnetic properties,and crystallization kinetics of the as-spun and annealed alloy ribbons of(Fe_(40-x)Co_xNi_(40)Si_(6.33)B_(12.66)Cu_1)_(0.97)Nb_(0.03),where x=0,6,7,8,9,prepared using the meltspinning method.The results show that adding a moderate amount of Co can improve the glass forming ability(GFA),the first peak crystallization temperature,and thermal stability of the as-spun alloy ribbons.With x=7,the two-stage crystallization temperature interval△Tx=90 exhibits optimal thermal stability,and the alloy annealed at 673 K for 10 minutes shows the favorable combined magnetic properties,with H_(c)=0.12 A/m,M_(s)=88.7 A·m^(2)/kg,andμ_(e)=13800.The magnetic domain results show that annealing removes numerous pinning points in the magnetic domains of the alloy ribbons,making the domain walls smoother and effectively reducing the pinning effect.
基金supported by the National Natural Science Foundation of China(Grant number:50071060)the National Development Project for Basic Scientific Research(Grant number:G2000067201).
文摘The Mg65Cu25Y10 melts were quenched at a temperature of 973 K under various pressures in the range of 2-5 GPa and ambient pressure. The microstructure of the solidified specimens has been investigated by X-ray diffraction, transmission electron microscope and electron probe microanalysis. Experimental results show that the pressure has a great influence on the solidification microstructure of the Mg65Cu25Y10. At ambient pressure, the solidification products are Mg2(Cu,Y) and a very small amount of Y2O3 inclusion. As the pressure is above 2 GPa, a new Cu2(Y,Mg) phase appears, while Y2O3 is not observed at the pressure of 3, 4 and 5 GPa. When the pressure increases from 2 GPa to 5 GPa, the grain sizes of Mg2(Cu,Y) and Cu2(Y,Mg) decrease from 125, 96 nm to 80, 7 nm, respectively. The mechanisms for the effects of the pressure on the phase evolution and microstructure during solidification process of Mg65Cu25Y10 alloy have been discussed.
基金Item Sponsored by National Natural Science Foundation of China(51131002,51301196)Fundamental Research Funds for the Central Universities of China(YWF-15-CLXY-002)Fok Ying Tong Education Foundation of China(142008)
文摘The surface of Ni_（61）Nb_（39） crystalline ingot was treated by laser surface melting with different processing parameters.A fully amorphous layer with a thickness of approximately 10μm could be produced on the top surface under optimal parameters.An amorphous-crystalline composite layer with the depth from 10 to 50μm,consisting of amorphous matrix and intermetallic phases of Ni_3 Nb and Ni_6Nb_7,could be formed.The micro-hardness（about 831HV）of the treated surface was remarkably improved by nearly 100% compared with the value of the crystalline substrate caused by the formation of the fully amorphous structure.A finite volume simulation was adopted to evaluate the temperature distribution in the laser-affected zone of Ni_（61）Nb_（39） alloys and to reveal the mechanism of glass formation in the laser-affected zone.
基金financial support from the National Key Research and Development Program of China(Grant No.2020YFB1805901)the National Science Fund for Distinguished Young Scholars(Grant No.62125502)+5 种基金the National Natural Science Foundation of China(Grant No.51972113)the Key Program of Guangzhou Scientific Research Special Project(Grant No.201904020013)the Key Research and Development Program of Guangzhou(Grant No.202007020003)the Science and Technology Project of Guangdong Province(Grant No.2021A0505030004)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(Grant No.2017BT01×137)the Fundamental Research Funds for the Central University.
文摘Advances in developing high entropy alloys and ceramics with improved physical properties have greatly broadened their application field from aerospace industry,public transportation to nuclear plants.In this review,we describe the concept of entropy engineering as applicable to inorganic non-metallic glasses,especially for tailoring and enhancing their mechanical,electrical,and optical properties.We also present opportunities and challenges in calculating entropy of inorganic non-metallic glass systems,correlating entropy to glass formation,and in developing functional inorganic non-metallic glasses via the entropy concept.
基金supported by the National Natural Science Foundation of China (Grant No. 51101004)the Fundamental Research Funds for the Central Universities
文摘Ab-initio molecular dynamics simulation was performed to investigate the local atomic structure of Co55Ta^0B35 alloys. Pair distribution function, coordination number, HA index and Voronoi polyhedra were used to describe the detailed local structure of this alloy. It was revealed Co7TalB2, Co6TalB2 and CosTa2B4 among the dominant （0 3 6 0）, （0 4 4 0）, （0 1 10 2） and （0 3 6 4） polyhedra were the basic local structure units in CossTal0B3s amorphous alloy. Furthermore, most of the dominant poly- hedra tended to have Ta atoms involved and these polyhedra may have a critical role during glass formation.
