Effects of rare-earth elements on the glass-forming ability and mechanical properties of Cu_(46)Zr_(47-x)Al_7M_x(M = Ce,Pr,Tb,and Gd) bulk metallic glasses

Cu46Zr47-xA17Mx （M = Ce, Pr, Tb, and Gd） bulk metallic glassy （BMG） alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability （GFA）, thermal stability, and mechanical properties of Cu46Zr47-xA17Mx were investigated. The GFA of Cu46Zr47-xA17Mx （M = Ce, Pr） alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xA17Thx（X = 2, 4, and 5） amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zr47-xA17Gdx（x = 2, 4, and 5） increases with increasing Gd. Tx and Tp of all decrease. Tg is dependent on the rare-earth element and its content. ATx for most of these alloys decreases except the Cu46Zra2Al7Gd5 alloy. The activation energies △Eg, △Ex, and △Ep for the Cu46Zr42A17Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respec- tively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43A17Pr4 alloy presents the least, Hv 479. The compressive strength （at.f.） of the Cu46Zra3A17Gd4 BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.

Formation and thermal stability of Cu-Zr-Al-Er bulk metallic glasses with high glass-forming ability

The formation and thermal stabilities of Cu46.25Zr46.25xAl7.5Erx (x=0 to 8) bulk metallic glasses (BMGs) were investigated. The addition of a small amount of Er (2at%) for replacing Zr effectively improves the glass-forming ability of Cu46.25Zr46.25Al7.5 alloy, and the glassy rod with a diameter of at least 12 mm can be formed. The glass transition temperature (Tg), temperature interval of su- percooled liquid region △Tx (=Tx-Tg), and reduced glass transition temperature Trg (=Tg/Tl) of Cu46.25Zr44.25Al7.5Er2 glassy alloy are 699 K, 62 K and 0.607, respectively.

Glass-forming Ability and Chemical Stability of Magneto-optical Glass Heavily Doped with Rare Earth Oxide

The glass-forming region of B2O3-Al2O3-SiO2 （BAS） glass heavily doped with rare earth oxides was investigated by an effective method, and the chemical stability was investigated by powder method. Influences of rare earth oxides on the glass-forming ability and the chemical stability of the BAS glass were also discussed. The experimental results show that the BAS glass-forming region expands firstly with the increase of the Tb2O3 content up to 30mol% and then shrinks. The acid-resistant capacity of the BAS glass doped with rare earth oxides is the lowest, the water-resistant capacity is secondary, and the alkali-resistant capacity is the best. Besides, the glass chemical stability can be improved by doping appropriate amount of rare earth oxides. Moreover, the stronger the ionic polarization ability of the rare earth ions is, the better the chemical stability of the BAS glass will be.

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.

Ferromagnetic Fe-based Amorphous Alloy with High Glass-forming Ability

A ferromagnetic amorphous Fe73Al4Ge2Nb1P10C6B4 alloy with high glass-forming ability was synthesized by melt spinning. The supercooled liquid region before crystallization reaches about 65.7 K. The crystallized structure consists of alpha -Fe, Fe3B, FeB, Fe3P and Fe3C phases. The Fe-based amorphous alloy exhibits good magnetic properties with a high saturation magnetization and a low saturated magnetostriction. The crystallization leads to an obvious decrease in the soft magnetic properties.

Correlation between the glass-forming ability and activation energy of crystallization for Zr_(75-x)Ni_(25)Al_x metallic glasses

The thermal stability and the kinetics of glass transition and crystallization for Zr75-xNi25Alx （x = 8-15） metallic glasses were investigated using differential scanning calorimetry （DSC） under continuous heating conditions. The apparent activation energy of glass transition rises monotonously with the A1 content increasing; the activation energy of crystallization increases with A1 changing from 8at% to 15at%, and then decreases with A1 further up to 24at%, which exhibits a good correlation to the thermal stability and the glass-forming ability （GFA）. The Zr60Ni25A115 metallic glass with the largest supercooled liquid region and GFA possesses the highest activation energy of crystallization. The relation between the thermal stability, GFA and activation energy of crystallization was discussed in terms of the primary precipitated phases.

New criterion in predicting glass forming ability of various glass-forming systems

It has been confirmed that glass-forming ability （GFA） of supercooled liquids is related to not only liquid phase stability but also the crystallization resistance. In this paper, it is found that the liquid region interval （T1 - Tg） characterized by the normalized parameter of Tg/T1 could reflect the stability of glass-forming liquids at the equilibrium state, whilst the normalization of supercooled liquid region △Tx=（Tx - Tg）, i.e. △Tx/Tx （wherein T1 is the liquidus temperature, Tg the glass transition temperature, and Tx the onset crystallization temperature） could indicate the crystallization resistance during glass formation. Thus, a new parameter, defined as ζ = Tg/T1＋△Tx/Tx is established to predict the GFA of supercooled liquids. In comparison with other commonly used criteria, this parameter demonstrates a better statistical correlation with the GFA for various glass-forming systems including metallic glasses, oxide glasses and cryoprotectants.

Effect of Al Addition on the Glass-Forming Ability and Magnetic Properties of a Gd-Co Binary Amorphous Alloy

The glass-forming ability （CFA） and magnetic properties of the Cd50 Co50-based amorphous alloy with AI addition substitution for Co are investigated. It is found that the CFA and magneto-caloric effect of the Gd50Co45Al5 amorphous alloy are better than Cd50Co50 amorphous alloy. The maximum magnetic entropy change （-△ Sm^peak） and the magnetic refrigerant capacity- of the amorphous alloy under a field of 5 T are about 6.64 J·kg^-1 K^-1 and 764 J·kg^-1, respectively. The field dependence of magnetic entropy change meets the one predicted by the mean field theory, which is investigated for a better understanding of the magneto-caloric behaviors of the Gdso Co45Al5 amorphous alloy.

Effect of Y element on atomic structure, glass forming ability,and magnetic properties of FeBC alloy

The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-forming ability and magnetic properties of Fe_(86-x)Y_xB_7C_7(x = 0, 5, 10 at.%) amorphous alloys via both experiments and ab initio molecular dynamics simulations. Furthermore, we explore the correlation between local atomic structures and properties. Our results demonstrate that an increased Y content in the alloys leads to a higher proportion of icosahedral clusters, which can potentially enhance both glass-forming ability and thermal stability. These findings have been experimentally validated. The analysis of the electron energy density and magnetic moment of the alloy reveals that the addition of Y leads to hybridization between Y-4d and Fe-3d orbitals, resulting in a reduction in ferromagnetic coupling between Fe atoms. This subsequently reduces the magnetic moment of Fe atoms as well as the total magnetic moment of the system, which is consistent with experimental results. The results could help understand the relationship between atomic structure and magnetic property,and providing valuable insights for enhancing the performance of metallic glasses in industrial applications.

Effect of niobium on glass-formation ability and soft magnetic properties of Gd-doping glassy alloys

The effect of niobium on glass-formation ability and soft magnetic properties were studied in Fe-Gd-B glassy alloys. The glassy alloys exhibited high glass-formation ability when the element of Nb was added. Bulk glassy rod （Fe0.87Co0.13）68.5Gd3.5Nb3B25 with a diameter up to 3 mm was produced by copper mold casting. The size of the atom might play an important role in increasing glass-formation ability. The coercive force of glassy （Fe0.87Co0.13）71.5.xGd3.sNbxB25 （x=1.2, 1.5, 2, 2.5, 3, 4） alloys decreased after the addition of niobium element and was in the range of 1.5-2.9 A/m. The permeability spectrum of （Fe0.87Co0.13）70.3Gd3.5Nb1.5B25 glassy ribbon showed that the relaxation frequency （f0） was 6.1 MHz.

Effect of Pd on GFA and Thermal Stability of Zr-based Bulk Amorphous Alloy

The effect of Pd addition on the glass-forming ability and thermal stability of the Zr55Al10Cu30Ni5-xPdx (x=0, 1, 3, 5 at. pct) alloys upon copper-mold casting has been investigated. The structure, thermal stability and microstructure were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. It was identified that a new bulk amorphous alloy with the larger supercooled liquid region Tx of 100 K is obtained with substituting Ni by 1 at. pct Pd. Furthermore, the origins that thermal stability and GFA change with increasing of Pd have also beer discussed.

STRUCTURE AND GLASS FORMING ABILITY(GFA)OF AMORPHOUS ALLOYS

A new microstructure model is developed for amorphous alloys,so called Cluster medel, in which the amorphous phase is thought of composing of randomly distributed ordered clusters of different sizes.Thermodynamic calculation on this model deduces a parameter describing the glass forming ability of metallic alloys:α_c=(1-2.08/Φ_m)T_g/T_m,where T_g is gass transition temperature,T_m is the melting temperature,and Φ_m is entralpy change of melting.It is believed that easy glass forming alloy systems have larger values of a_c.This new criterion of GFA not only provides the theoretical background for several GFA criteria in the literature cited,but also can predict the GFA of many alloy systems more reasonably and accurately.

Thermodynamic model for glass forming ability of ternary metallic glass systems

The thermodynamic model of multicomponent chemical short range order (MCSRO) was established in order to evaluate the glass forming ability (GFA) of ternary alloys. Comprehensive numerical calculations using MSCRO software were conducted to obtain the composition dependence of the MCSRO undercooling in Zr Ni Cu, Zr Si Cu and Pd Si Cu ternary systems. By the MCSRO undercooling principle, the composition range of Zr Ni Cu system with optimum GFA is determined to be 62.5 ～ 75 Zr, 5～ 20 Cu, 12.5 ～ 25 Ni ( n (Ni)/ n (Cu)=1～5). The TTT curves of Zr Ni Cu system were also calculated based on the MCSRO model. The critical cooling rates for Zr based alloy with deep MSCRO undercooling are estimated to be as low as 100?K/s, which is consistent with the practical cooling rate in the preparation of Zr based bulk metallic glass (BMG). The calculation also illustrates that the easy glass forming systems such as Pd based alloys exhibit an extraordinary deep MCSRO undercooling. It is shown that the thermodynamic model of MCSRO provides an effective method for the alloy designing of BMG.

Evaluation of glass forming ability of alloys

Key step of exploiting a new type BMG (Bulk Metallic Glass) is quickly judging GFA (Glass Forming Ability) of the alloys. The mole melting heats of BMGs are calculated using the weighted averages principle. The reliability and limitation of Trg criterion for GFA are discussed. The reason why Trg of BMGs is larger than 0.5 is discussed. Two new criteria for GFA, ΔHmg and ΔGg, are proposed. GFA sequence of BMGs is calculated using the ΔHmg criterion, the result agrees with that of A. Inoue and the Rc criterion. Furthermore, as an example, the Rc of the alloys developed by Chuang DONG et al is calculated using the ΔHmg and ΔGg. The ascending sequence of these alloys calculated with the ΔHmg criterion agrees with that of Chuang DONG et al. On the contrary, the result by the ΔGg criterion is in contrary with Chuang DONG et al, indicating that the ΔHmg criterion is better and more convenient than the ΔGg criterion. Calculation showed that the optimum ΔHmg is -15.16 kJ/mol.

Deciphering the glass-forming ability of Al_(2)O_(3)-Y_(2)O_(3)system from temperature susceptibility of melt structure

Despite its significance in both fundamental science and industrial applications,the glass-forming transition in the Al_(2)O_(3)-Y_(2)O_(3)(AY)refractory system is not yet fully understood due to the elusive structure evolution upon cooling.Here,atomic-scale structural changes in AY-bearing melts with different compositions and temperatures are tracked by employing in situ high-energy synchrotron X-ray diffraction and empirical potential structure refinement simulation.We find that the glass-forming abilities(GFA)of AY-bearing melts are intriguingly correlated with the dependence of melt structure on temperature.In the case of the Al_(2)O_(3)and Y_(3)A_(l5)O_(12)(YAG),the observed large structural changes from superheating to under-cooling melt(i.e.,higher temperature susceptibility)correspond to a low GFA.Conversely,the 74Al_(2)O_(3)-26Y_(2)O_(3)(AY26)melt,with the smallest temperature susceptibility,exhibits the highest GFA.Simulation models illustrate that the temperature susceptibility of melt is associated with its atomic arrangement,especially the stability of cation-cation pairs.A balanced network(in AY26 melt),where the unsteady OAl3 tri-clusters are minimized and steady apex-to-apex connections between adjacent network units are abundant,contributes to stabilizing cationic interactions.This,in turn,fosters the formation of largesized Al-O-Al rings,which topologically facilitates the subsequent glass-forming transition.Our findings provide new structural insight into the GFA of AY-bearing melts and may expand to other unconventional glass-forming systems to accelerate glassy materials design.

Effects of Cu,Fe and Co addition on the glass-forming ability and mechanical properties of Zr-Al-Ni bulk metallic glasses

The thermal stability,glass-forming ability(GFA) and mechanical properties of Zr60Al15Ni25xTMx(TM = Cu,Fe and Co,x = 0-10) bulk metallic glasses(BMGs) were systematically investigated.Additional 5-10 at.% Cu greatly enhances the thermal stability and GFA of the base alloy.Zr60Al15Ni15Cu10 BMG exhibits the largest supercooled liquid region of 104 K and critical diameter of 18 mm.However,addition of 5-10 at.% Fe or Co decrease the thermal stability and GFA.In addition,the plasticity of the BMG can be improved by adding of Cu,while the strength is decreased slightly.Zr60Al15Ni20Cu5 BMG has the largest plastic strain of 5.5% with a yield stress of 1755 MPa and Young's modulus of 83 GPa.Addition of Co brings an increase of strength but a lower of plasticity,and additional Fe reduces the strength and plasticity simultaneously.

Effects of Mo additions on the glass-forming ability and magnetic properties of bulk amorphous Fe-C-Si-B-P-Mo alloys

Glass formation, mechanical and magnetic properties of the Fe76-xC7.0Si3.3B5.0P8.7Mox (x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of Mo for Fe, glass-forming ability (GFA) was significantly enhanced and fully amorphous rods with a diameter of up to 5 mm were produced in the alloy with 3% Mo. The Mo-containing amorphous alloys also exhibited high fracture strength of 3635–3881 MPa and excellent magnetic properties including a high saturation magnetization of 1.10–1.41 T, a high Curie temperature and a low coercive force. The unique combination of high GFA, high fracture strength and excellent magnetic properties make the newly developed bulk metallic glasses viable for practical engineering applications.

Glass-forming ability and corrosion performance of Mn-doped Mg-Zn-Ca amorphous alloys for biomedical applications

In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion performance in simulated body fluid of Mg65Zn30Ca5 alloy were studied through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and electrochemical and immersion tests. Results show that with the Mn addition increasing, all the ribbon samples are completely in amorphous state. However, the microstructure of 2-mm rod samples transfers from fully amorphous for the Mn-free alloy to almost polycrystalline state with precipitated Mg, Mn, and MgZn phases. Glass-forming ability of Mg65Zn30Ca5 alloy is decreased by Mn addition. Results of electrochemical and immersion tests demon- strate that the Mn-doped samples exhibit more negative corrosion potential and larger corrosion current density, suggesting that the corrosion resistance decreases with doping amount of Mn element increasing.

Enhancement of glass-forming ability and thermal stability of a soft magnetic Co_(75)B_(25)metallic glass by micro-alloying Y and Nb

Soft magnetic Co-based Co-Y-Nb-B bulk metallic glasses(BMGs)without Fe have been developed by micro-alloying Y and Nb into a C075B25 alloy.First,addition of 3^at.%Y promotes the occurrence of glass transition and increases the supercooled liquid stability and magnetic softness.C0_(71.5)Y_(35)B_(25) metallic glass possesses a large supercooled liquid region(△T_(x))of 33 K and low coercivity(H_(c))of l.5 A/m.Subsequent alloying 2-4 at.% Nb into C0_(71.5)Y_(35)B_(25) alloy further enlarges △T_(x) to 50 K,lowers H_(c) to 0.9 A/m,and enables the formation of BMGs with a critical sample diameter up to 2.0 mm.The alloying Nb causes the formation of complex(Co,Nb,Y)_(23)B_(6) competing phase during crystallization and widens the melt undercooling during solidification,which improves the supercooled liquid stability and glass-forming ability,respectively.Co-Y-Nb-B BMGs also exhibit good soft magnetic and mechanical properties,i.e.,lowH_(c)of 0.9-1.2 A/m,relatively high saturation magnetic flux density of 0.36-0.57 T,high yielding strength of 3877-3930 MPa with plastic strain of 0.2%-0.3%,and high Vickers hardness of 1156-1201.The developed soft magnetic Co-based BMGs are promising for applications as structural and functional materials.

Comparative Study of the Magnetic Properties and Glass-Forming Ability of Fe-Based Bulk Metallic Glass with Minor Mn, Co, Ni, and Cu Additions

Fe43MsCra5Mo14C15B6Y2 （M = Mn, Co, Ni, and Cu in at.%） bulk metallic glasses （BMGs） are synthesized using the suction casting technique, and the glass-forming ability （GFA）, microstructure, and thermal and magnetic properties of these glasses are extensively examined using X-ray diffraction, differential scanning calorimeter, and vibrating sample magnetometer techniques. Among the four BMG alloys, Fe43NisCr15Mo14C15B6Y2 exhibits the lowest coercivity and the highest saturation magnetization, Curie temperature, effective magnetic moment, and GFA. By contrast, Fe43MnsCrlsMo14C15B6Y2 presents the poorest magnetic properties, such as the highest coercivity and the lowest saturation magnetization, Curie temperature, and effective magnetic moment. Fe43Cu5Cr15MolaC15B6Y2 demonstrates the lowest thermal stability and GFA. The observed thermal, structural, and magnetic properties of these BMG alloys are discussed in terms of the kinetics of BMG synthesization and the formation of different ferromagnetic, ferrimagnetic, and antiferromagnetic phases.