Formation, Structure and Properties of Bulk Metallic Glasses

Bulk metallic glasses with up to 72 mm critical section thickness have been obtained by conventional casting techniques and the properties of these materials, particularly the mechanical and magnetic properties have been studied. These materials have been demonstrated to have novel properties which are fundamentally different from their crystalline counterparts. The recent status of research and development in formation, structure and properties of bulk metallic glasses is reviewed. The techniques to produce such bulk glasses are summarized and the glass forming ability and the critical cooling rate of these materials are discussed. Further consideration of the development and application of this new class of materiaIs will be proposed.

Preparation,Structures,Thermal Properties and Sintering Behaviors of B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 Glass

B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with different Al_2O_3 contents（1mol%, 3mol%, 5mol%, and 7mol%） was prepared, and it was intended to be used as lead-free and low-melting glass sealants for solid oxide fuel cells. The effects of Al_2O_3 content on the structures, thermal properties, and sintering behaviors of the B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass were investigated in detail. The Al_2O_3 content largely influenced the structures and thermal properties of the glass. When the Al_2O_3 content 5mol%, the transition temperature of the glass decreased with the Al_2O_3 content, while the crystallization temperature increased with the Al_2O_3 content. However, higher Al_2O_3 content degraded the stability of the glass. The B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with 5 mol% Al_2O_3 content exhibits the optimal sintering densification characteristics and can be used as glass sealants for solid oxide fuel cells.

Analysis of Mechanical Properties of Injection Molded Short Glass Fibre (SGF)/Calcite/ABS Composites

Acrylonitrile-butadiene-Styrene (ABS), with and without calcium carbonate (calcite) particles,was used as the matrix for reinforcement with as-received short-glass fibres (were originallytreated by the manufacturer) and sized short-glass fibres with two amino-silane coupling agents.The calcite particle content is 0, 11.7 and 23.5 vol. pct for the matrices. The glass fiber contentis 0, 10 and 15 vol. pct. The matrix materials and corresponding composites were compoundedusing a twin screw extruder and dumbbell-shaped tensile bars were prepared with an injectionmolding process. The tensile and flexural properties as well as the unnotched and notchedCharpy impact energies of short glass fibre/calcite/ABS composites were studied in this paper.The effects of fibres, fibre surface treatments and particles on these mechanical properties ofthe composites were discussed in detail. An importarit information was obtained, which is thatthe tensile and flexural strengths of hybrid SGF/calcite/ABS composites are the same as thoseof corresponding fibre composites when the ratio of the interfacial adhesion strength betweenparticles and matrix to that between fibres and matrix is higher than certain value. otherwise theformer are lower than the latter.

Effect of Ga_2O_3 on Structure and Properties of Calcium Aluminate Glasses

The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter（DSC）, and infrared spectrum methods. The results show that calcium aluminate glass network only consists of [AlO_4] tetrahedral units. With the gradual addition of Ga_2O_3, the quantity of [GaO_4] tetrahedral units increases. Substitution of Ga_2O_3 for Al_2O_3 results in a decrease in Tg, Tx, and Tp, and an increase in the thermal stable index ΔT. Similarly, the absorption band around 3.0 μm obviously reduces and the transparency in 4.0-6.0 μm rapidly increases with increasing Ga_2O_3 content. However, the chemical stability of calcium aluminate glasses decreases if Ga_2O_3 is introduced due to the increasing of [GaO_4] units in the glass network.

Formation and Mechanical Properties of Zr-Nb-Cu-Ni-Al-Lu Bulk Glassy Alloys with Superior Glass-Forming Ability

Glass-forming ability（GFA） and mechanical properties of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x= 0-3 at%） alloys have been investigated.The GFA of Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is dramatically enhanced by adding Lu.The（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy possesses the highest GFA in the studied Zr-Nb-Cu-Ni-Al-Lu alloys,with its critical diameter for glass formation reaching 20 mm by copper-mould casting method,while that of the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is 7 mm.The critical diameters of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x =1 at%and 3 at%） alloys are 15 mm and 12 mm,respectively.The Lu addition to Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy induces the change of initial crystallization phases from face-centred-cubic Zr_2Ni and tetragonal Zr_2Ni phases for the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy to an icosahedral quasi-crystalline phase for the Lu-doped alloys,which may be the origin for the enhanced GFA of the Lu-doped alloys.The compressive fracture strength and plastic strain of the bulk glassy（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy are1 610 MPa and 1.5%,respectively.

Dielectric Properties of Some Borate Glasses

The dielectric constant, e', and the dielectric loss. e', for some selected lead borate glasses within the frequency band 105 to 107 Hz and the temperature range (20-50)'C were measured. The dielectric dispersion and the dielectric loss absorption bands were observed. the relaxation time, the activation enthalpy and entropy change of the dielectric relaxation were calculated. The results obtained were discussed and correlated to the internal network structure of the glasses studied.

Mechanical Properties and Solidified Mechanism of Tailings Mortar with Waste Glass

In order to improve the comprehensive utilization of solid waste such as iron tailings and waste glass and so on,mechanical property test of cement tailings mortar mixed waste glass and curing mechanism research were conducted in the key materials mechanics lab of Liaoning province.The experimental results show that adding waste glass particles can improve the grain size distribution of tailings.The effect is proportional to the content.The compressive strength of tailings mortar has increased significantly.The fineness modulus of tailings mortar mixture adding waste glass powder was gradually reducing with the increase of the dosage of waste glass powder,but the compressive strength of the mixture has gradually enhanced with the increase of the dosage.Microscopic analysis shows that the waste glass particles in the mortar mainly play a role of coarse aggregate and glass powder after grinding fine below a certain size shows strong volcanic activity,which can act hydration with tailings,at the same time glass powder also,plays a role in fine aggregate filling.Therefore,all of glass particles and glass powder can be used as the additive material for improving and optimizing the mechanical property of tailings mortar.

Structural and Magnetic Properties of MnO-P_2O_5-PbO Glasses

The xMnO(100-x)[2P2O5.PbO] glasses were prepared with MnO concentration being in the range of 0≤x≤50 mole fraction and were investigated by EPR spectroscopy and magneticsusceptibility measurements. Octahedral symmetric sites tetragonally distorted were detected for x≤5 mole fraction MnO. Only Mn2+ ions were identified in these glasses, involved in dipoledipole interactions

STUDY ON THE INFRARED TRANSMITTING As_2Te_3-BASED CHALCOHALIDE GLASSES

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-

High plastic Zr–Cu–Fe–Al–Nb bulk metallic glasses for biomedical applications

Four Zr–Cu–Fe–Al-based bulk metallic glasses（BMGs） with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties, and corrosion resistance properties of the prepared BMGs were investigated. These BMGs exhibit moderate glass forming abilities along with superior fracture and yield strengths compared to previously reported Zr–Cu–Fe–Al BMGs. Specifically, the addition of Nb into this quaternary system remarkably increases the plastic strain to 27.5%, which is related to the high Poisson＇s ratio and low Young＇s and shear moduli. The Nb-bearing BMGs also exhibit a lower corrosion current density by about one order of magnitude and a wider passive region than 316 L steel in phosphate buffer solution（PBS, pH 7.4）. The combination of the optimized composition with high deformation ability, low Young＇s modulus, and excellent corrosion resistance properties indicates that this kind of BMG is promising for biomedical applications.

Thermal and Mechanical Properties of Epoxy Resin Modified with N-(4-hydroxyphenyl)terahydrophthalic Anhydrideimide

A novel epoxy-imide resin based on diglycidyl ether of bisphenol-A and N-（4-hydroxyphenyl）terahydrophthalic anhydrideimide（HTAM） was synthesized. The structural characterization of the epoxy-imide resin was conducted by FT-IR spectra. 4,4＇-diaminodiphneylmethane（DDM） was used as a curing agent for the epoxy-imide resin. The thermal properties of the cured resin were evaluated with dynamic mechanical analyses（DMA） and thermogravimetric analysis（TGA）. The results showed that the cured resin exhibited a high glass transition temperature（Tg） of 186 ℃ when the molar amount of HTAM was 0.04 mol in the resin. The yields of the cured resin at 800 ℃ raised from 16.45% to 19.41%. The flexural properties were also measured, the flexural strength raised from 79.4 to 95.7 MPa, and the flexural modulus exhibited from 2.6 to 3.0 GPa.

Effect of Nd^(3+) on spectroscopic properties of lithium borate glasses

The spectroscopic properties of lithium borate glasses as a function of Nd3＋ ions concentration were reported.Optical absorption spectra of these glasses showed a number of absorption bands in ultra violet and visible region.Optical absorption edge was found to shift towards the longer wavelength（red shift） with increase in Nd2O3.Luminescence spectra revealed three major bands at 902, 1063 and 1334 nm which was due to 4F3/2→4I9/2, 11/2 ＆13/2 transitions of Nd3＋ ions.Luminescence intensity was maximum for 1 mol.% Nd2O3 and further increase in Nd2O3 resulted in luminescence quenching.The luminescence quenching behavior at higher concentration of Nd2O3 was attributed to the Nd3＋-Nd3＋ interaction in the glass matrix.An absorption and emission property of these glasses suggested that these glasses could be useful for 1.06 μm infrared laser applications.

Thermal and structural properties of Nd2O3-doped calcium boroaluminate glasses

Nd^3＋ doped CaO-Al2O-B2O3-CaF2 glasses were prepared by conventional melt-quenching technique,and their structural and thermal properties were studied.The amorphous nature of these samples was confirmed by X-ray diffraction（XRD）.The measured density showed an increase with Nd2O3 doping,at the expense of CaO.Raman spectra presented changes with addition of Nd2O3,which indicated that the network structure of the glasses studied presented various borate groups,such as tetraborates,metaborates,ortho-borates and pyroborates units.The N4 values calculated from FTIR spectra revealed that incorporation of Nd2O3 into glass network converted the structural units from BO4 to BO3.From the analysis of DTA curves,we verified that Tg increased with the addition of Nd2O3;it was similar to the behavior caused by modifier oxides in the structure of borate glasses.Besides that,the calculated glass stability Tx–Tg for doped samples presented a decrease if compared to the undoped glass.Specific heat and thermal conductivity did not present significant changes with Nd2O3 concentration,up to 2.30 mol.%.The results of density,DTA,Raman and FTIR reinforced the idea that Nd2O3 acted as network modifier.

Mechanical and Magnetic Properties of New(Fe,Co,Ni)–B–Si–Ta Bulk Glassy Alloys

The alloying effects of the like-atom substitution of Ni and Co for Fe on the various properties of Fe_（70）B_（16.7）Si_（8.3）Ta_5 metallic glass are investigated in this present work. New Fe-based bulk glassy alloys, namely Fe_（60–x）Co_xNi_（10）B_（16.7）Si_（8.3）Ta_5（at.%;x = 10, 20 and 30） with critical diameters up to 1.5 mm, were made by means of copper mold casting.A new glass-forming ability indicator, viz., the enthalpy of supercooled liquid, has been introduced for assessment of the glass-forming abilities（GFAs） of these Fe-based multi-component alloys. Nano-indentation results indicate that the calculated elastic modulus and hardness of the bulk glassy alloys are lower than those of the Fe_（70）B_（16.7）Si_（8.3）Ta_5 alloy.Among these bulk glassy alloys, Fe_（70）B_（16.7）Si_（8.3）Ta_5 exhibits the large elastic modulus and hardness with values of 178 ± 1GPa and 12.9 ± 0.1 GPa, respectively. All the bulk glassy alloys exhibit good soft magnetic properties with high saturation magnetization Bs^0.75–1.04 T but low coercive force Hc^0.2–5.2 A/m.

Flexural Strength and Weibull Analysis of Bulk Metallic Glasses

The flexural strength reliability of bulk metallic glasses （BMGs） plates is analyzed using Weibull statistics. The Weibull modulus （m） and characteristic strength （σ0） of the Zr48Cu45AI7 BMG are 34 and 2630 MPa, respectively, which are much higher than the values of fine ceramics （m 〈 30, σ0 〈 1600 MPa）. In particular, the m values obtained by flexural strength and compressive strength statistics of the Mg61Cu28Gd11 BMG are 5 and 33, respectively, indicating that the m values of BMGs are test method dependent, and only the m values obtained by flexural strength statistics can be used to make a convincible comparison with those of ceramics.