A new TiCuHfSi bulk metallic glass with potential for biomedical applications

A new Ti_41.3Cu_43.7Hf_13.9Si_1.1 bulk metallic glass (BMG), free of Ni, Al and Be elements, was designed using the proper mixing of binary deep eutectics. The alloy exhibited excellent glass forming ability (GFA) and could be cast into single glassy rod up to 3 mm in diameter by copper mould casting method. The appropriate atomic-size mismatch, the large negative heat of mixing among constituent elements, and the possible formation of glassy HfSiO₄ facilitated its superior GFA. The BMG also showed good mechanical properties with fracture strength of 1685 MPa and Young’s modulus of 95 GPa as well as better corrosion resistance in both NaCl and Hank’s solutions, compared with pure Ti and Ti–6Al–4V alloy. The above results demonstrated that the developed BMG is promising in biomedical applications.     

Investigation of glass-forming ability,deformation and corrosion behavior of Ni-free Ti-based BMG alloys designed for application as dental implants

We developed new Ti-based bulk metallic glassy (BMG) alloys in Ti–Zr–Pd–Cu–Sn system without Ni element for application as biomaterials. These BMG alloys have a high potential to be applied as metallic biomaterials in various forms, such as melt-spun ribbons and cylindrical rods with a diameter of 4 mm. We also investigated of new Ti-based BMG alloys with higher glass-forming ability (GFA) for medical market as dental implants. These Ti-based BMG alloys do not contain Ni, Al and Be elements which are well known to be harmful for human body. In particular, a rod sample of the Ti_44.1Zr_9.8Pd_9.8Cu_30.38Sn_3.92Nb₂ BMG alloy with a diameter of 3 mm produced by copper mold casting exhibits a compressive strength of 1990 MPa and a Young's modulus of 99 GPa. In addition, the Ti_44.1Zr_9.8Pd_9.8Cu_30.38Sn_3.92Nb₂ BMG shows a large supercooled liquid region of 62 K and a reduced glass-transition temperature, T_rg( = T_g / T_m) of 0.61. The high thermal stability of the supercooled liquid allowed the fabrication of cylindrical rod specimens up to 5 mm in diameter. Thus the studied alloy exhibits high glass-forming ability (GFA) and a large size enough to be used for dental implants. The Ti_44.1Zr_9.8Pd_9.8Cu_30.38Sn_3.92Nb₂ BMG alloy also has a high corrosion resistance and is passivated at the lower passive current density of approximately 10^? 2 A m^? 2, 10^? 3 A m^? 2 and 10^? 2 A m^? 2, in 1 mass% lactic acid, PBS (phosphate-buffered saline without calcium and magnesium salts solution) and HBSS (Hank's balance salt solution without calcium, magnesium and phenol red), respectively, at 310 K, which are lower than those of pure Titanium and Ti–6Al–4V alloy.     

In vivo evaluation of Zr-based bulk metallic glass alloy intramedullary nails in rat femora

Zr-based bulk metallic glasses (BMG) show high corrosion resistance in vitro and higher strength and lower Young’s modulus than crystalline alloys with the similar composition. This study aimed to perform an in vivo evaluation of Zr₆₅Al_7.5Ni₁₀Cu_17.5 BMG. Osteotomy of the femur was done in rats and stabilized with intramedullary nails made of Zr₆₅Al_7.5Ni₁₀Cu_17.5 BMG, Ti–6Al–4V alloy, or 316L stainless steel. Systemic and local effects of each type of nail were evaluated by measuring the levels of Cu and Ni in the blood and the surrounding soft tissue. Changes of the surface of each nail were examined by scanning electron microscopy (SEM). Healing of the osteotomy was evaluated by peripheral quantitative computed tomography and mechanical testing. No increase of Cu and Ni levels was recognized. Surface of the BMG showed no noticeable change, while Ti–6Al–4V alloy showed Ca and P deposition and 316L stainless steel showed surface irregularities and pitting by SEM observation. The stress strain index, maximum torque, torsional stiffness, and energy absorption values were larger for the BMG than those for Ti–6Al–4V alloy, although there was no significant difference. The Zr-based BMG can promote osteotomy healing as fast as Ti–6Al–4V alloy, with the possible advantage of the Zr-based BMG that bone bonding is less likely, allowing easier nail removal compared with Ti–6Al–4V alloy. The Zr-based BMG is promising for the use in osteosynthetic devices that are eventually removed.     

A comparison of crystallization behaviors of laser spot welded Zr–Cu–Ag–Al and Zr–Cu–Ni–Al bulk metallic glasses

A novel Ni-free Zr–Cu–Ag–Al ((Zr₄₈Cu₃₆Ag₈Al₈)Si_0.75) and a Zr–Cu–Ni–Al ((Zr₅₃Cu₃₀Ni₉Al₈)Si_0.5) bulk metallic glass (BMG), for comparison, were employed for Nd:YAG laser spot welding with three pre-selected energy inputs, including a low (6.2 J), a medium (8.0 J) and a high (9.2 J) energy input. After the welding process, the microstructure evolution, glass-forming ability (GFA) and mechanical properties of the welded samples were determined by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and the Vicker's microhardness test.     

Complete Composition Tunability of Cu(Ni)-Ti-Zr Alloys for Bulk Metallic Glass Formation

In the Cu-Zr-Ti ternary system, a new composition zone of bulk metallic glasses (BMGs) formation was discovered, locating at the 55-57 at. Pct Cu, 30-31 at. Pct Ti and 13-14 at. Pct Zr, and near Cu-Ti binary subsystem rather than the Cu-Zr binary. For these alloys, BMG rods of 2 mm in diameter can be fabricated by using copper mould casting. It is expected that these BMG-forming alloys correlate with (L→CuTi+Cu2TiZr+Cu61Zr14) eutectic reaction that the undercooled melt undergoes during solidification. Adopting "3D pinpointing ap-proach", compositional dependence of glass-forming ability (GFA) in Cu(Ni)-Ti-Zr pseudo ternary system was revisited. Optimized BMG-forming composition is located at Cu50.4Ni5.6Ti31Zr13, with a critical diameter of 6 mm for complete BMG formation. Its GFA is significantly superior to Vit 101 (Cu47Ni8Ti34Zr11) previously developed by Caltech group. The effect that the GFA of the ternary base alloy was improved by substitution of Ni for Cu is attributed to a role of retarding the crystallization of Cu51Zr14 intermetallics.     

First-principles study of NiAl microalloyed with Sc,Y, La and Nd

The structural, elastic, and electronic properties of NiAl microalloyed with rare earth elements (REEs) Sc, Y, La and Nd are investigated by using Density Functional Theory (DFT). It is found that Sc and La tend to substitute for Al site, while Y and Nd tend to substitute for Ni site, and Nd causes the largest lattice distortion. The elastic constants show that Sc, Y, La and Nd improve the ductility of NiAl. Ni₈Al₇La is more ductile and Ni₈Al₇Sc is harder, which could be explained by the increase of ionicity between Ni and Al in Ni₈Al₇La. The results agree well with the available experimental data and other theoretical results.     

On the glass-forming ability of Ni–P binary alloys

The composition dependence of glass-forming ability (GFA) of Ni–P binary alloys was systematically examined by fabricating ribbons of different thicknesses, and the microhardness of the glassy ribbon was measured. The eutectic alloy Ni_80.4P_19.6 has the best GFA and the highest microhardness in glassy state. As the alloy composition is deviated from the eutectic composition, both GFA and microhardness decrease, accompanied with an increasing full width at half maximum of the main broad peak in the X-ray diffraction spectrum of the glassy ribbon. All these results indicate a close correlation among microstructure, GFA and microhardness for the metallic glass.     

Corrosion performances in simulated body fluids and cytotoxicity evaluation of Fe-based bulk metallic glasses

The aim of this work is to investigate the corrosion resistance and biocompatibility of three kinds of Fe based bulk metallic glasses (BMGs), Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂ (BMG1), (Fe₄₄Cr₅Co₅Mo₁₃Mn₁₁C₁₆B₆)₉₈Y₂ (BMG2), and Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ (BMG3) by electrochemical measurements and indirect contact cytotoxicity assays, respectively. In comparison with 316 L SS biomedical steel, Fe based BMGs show better corrosion resistance in both simulated body fluids (Hank's solution and artificial saliva). The OCP curves show that the passive film on the Fe based BMG surfaces is quite stable, like 316 L SS. The corrosion current densities obtained from the anodic polarization curves from the lowest to highest are as follows: BMG3 < BMG1 < BMG2 < 316 L SS. The EIS analysis indicates that the Fe Based BMGs have larger polarization resistance value than that of 316 L SS except for BMG2 in artificial saliva. The pitting corrosion potentials of Fe based BMGs are much higher than that of the 316 L SS, resulting in very few ions releasing into the electrolytes while a significant amount of Ni and Fe ions release was found for 316 L SS under the same condition. The indirect cytotoxicity results suggest that all three Fe based BMG extracts have no cytotoxicity to L929 and NIH3T3 cells. All these results demonstrate that Fe based BMGs will open up a new path for the biomedical applications, especially in dental implantology.     

Glass-Forming Ability for Nd_(70-x)Fe_(20)Al_(10)Y_x and Nd_(60-x)Fe_(30)Al_(10)Y_x Alloys

The glass-forming ability (GFA) of Nd70-xFe2oAl10Yx and Nd60-xFe30Al10Yx (0< x <15) alloys produced by Cu mold casting was investigated. Except Y=5 at. pct, bulk amorphous Nd70-xFe20Al10Yx alloys up to 2 mm in diameter were obtained. The GFA for Nd60-xFe30Al10Yx alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy. The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, Tg, and the supercooled liquid region, TX, are 776 K and 58 K, respectively. The GFA and thermal stability of the Nd-Fe-AI-Y a     

Interatomic potential to predict the glass-forming ability of Ni–Nb–Mo ternary alloys

With the recently proposed formulation, an interatomic n-body potential was first constructed for the Ni–Nb–Mo metal system, and then applied to atomistic simulations to investigate the glass formation of the Ni–Nb–Mo ternary alloys. The simulations not only clarify the atomistic process of the metallic glass formation but also predict for the ternary system of a quantitative composition region within which metallic glass formation is energetically favored. In addition, the energy difference between crystalline solid solution and disordered phase i.e., the driving force for a supersaturated solid solution to amorphize could be considered as an indicator of the glass-forming ability (GFA) for a specific alloy. The GFAs of a series of Ni–Nb–Mo alloys were derived from the simulations, leading to pinpoint the Ni₅₅Nb₃₀Mo₁₅ alloy with superior GFA in this ternary metal system. The Ni₅₅Nb₃₀Mo₁₅ alloy can be considered as the optimized ternary metallic glass for thermal stability and manufacturability.     

Formation of ternary Mg-Cu-Dy bulk metallic glasses

The glass-forming ability (GFA) of ternary Mg-Cu-Dy alloys was systematically investigated by using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) techniques. The results showed that a series of ternary Mg-Cu-Dy bulk metallic glasses (BGMs) with a diameter of 4–8 mm were successfully fabricated in the system with conventional Cu-mold casting method. Mg₅₅Cu₃₂Dy₁₃, Mg₆₀Cu₂₇Dy₁₃, Mg₆₅Cu₂₅Dy₁₀ and Mg₇₀Cu₁₇Dy₁₃ BMGs exhibit a clear glass transition, a broad supercooled liquid region and different crystallization and melting behaviours. They have supercooled liquid region (ΔT _x) from 41 K to 65 K, reduced glass transition temperature (T _rg) from 0·5363 to 0·5974 and γ parameter from 0·4038 to 0·4136. The γ shows a relatively good agreement with the GFA of the BGMs. On the other hand, a high fracture compressive strength of 624 MPa was obtained for Mg₆₀Cu₂₇Dy₁₃ BMG.     

Influences of Similar Elements on Glass Forming Ability and Magnetic Properties in Al-Ni-La Amorphous Alloy

Similar element substitution has been applied for improving glass forming ability (GFA) in Al₈₆Ni₉La₅ amorphous alloy. The effects of La-Ce and Ni-Co pairs on the GFA, magnetic properties and hardness of Al-Ni-La alloy were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), magnetometer and hardness-tester. The results show the GFA of the samples in the order of Al86(Ni_0:5Co_0:5)9(La_0:5Ce_0:5)5< Al₈₆Ni₉La₅<Al₈₆Ni₉(La_0:5Ce_0:5)₅, implying that similar element substitution has a limited enhancing effect on the GFA of the present Al-Ni-La alloy. In addition, the measured samples display a diamagnetic behavior at room temperature. The variations of diamagnetic behavior as well as the microhardness of the samples are strongly dependent on the icrostructure, i.e., the amounts of the icosahedral structure and precipitates, after the similar element substitution in the Al-Ni-La alloy.     

Nd60Fe30 − xNixAl10 bulk metallic glasses with high hard magnetic properties

Bulk metallic glasses (BMGs) Nd₆₀Fe_30 − xNi_xAl₁₀ were prepared by suction cast method. The glass forming abilities (GFAs) and the hard magnetic properties of the BMGs were examined by differential scanning calorimeter (DSC) and vibrating sample magnetometer (VSM), respectively. The results show that the largest GFA (T_x / T_m = 0.61) of the alloys was obtained when Fe was substituted by 10% Ni and the rods of Nd₆₀Fe₂₀Ni₁₀Al₁₀ have the coercivity up to 323 kA/m and the remanence up to 9.41 Am²/kg as high as Nd-Fe-Co-Al, the Nd-Fe-based BMGs with highest hard magnetic properties up to date. The homogeneous distribution of Fe-rich nano-clusters, Nd(FeNiAl)₂, in amorphous matrix is responsible for the enhancement.     

Mg65Cu25Y10大块金属玻璃的玻璃转变行为与玻璃形成能力

简要回顾了Mg基大块金属玻璃(BMG)的历史,试图揭示其开发进程中所蕴藏的科学思想,以期能够给今后的研究工作带来某些启示;通过对一些实验结果的分析,探讨了Mg65Cu25Y10 BMG的玻璃转变行为与玻璃形成能力(GFA)之间的内在联系,并最终展示合金大的GFA.     

Hydrogen storage properties and phase structures of RMg2Ni (R = La,Ce, Pr,Nd) alloys

RMg₂Ni alloys were prepared by inductive melting where R is rare earth (R = La, Ce, Pr, Nd). X-ray diffraction (XRD) patterns revealed a single-phase composition of RMg₂Ni phase when R was one of the three elements (La, Pr, Nd), and a double-phase composition of CeMg₂Ni and CeMg₃ phases when R was Ce. In the hydriding process, RMg₂Ni phases transformed to rare earth hydrides (R-H) and Mg₂NiH₄ phase, and for CeMg₃ phase, it is decomposed to CeH_2.74 and MgH₂ phases. The enthalpy change of Mg₂Ni phase in RMg₂Ni alloys during the hydriding/dehydriding process was smaller compared with that of pristine Mg₂Ni alloy, which could be attributed to the existence of R-H. The hydrogen storage properties of RMg₂Ni alloys changed with different R compositions in R-H. At 573 K, the NdMg₂Ni alloy had the highest hydrogen storage capacity and dehydriding plateau, and the descending order of hysteresis was PrMg₂Ni < NdMg₂Ni < CeMg₂Ni < LaMg₂Ni, which suggested that the PrMg₂Ni alloy exhibited a better cycling stability and reversibility than the other three alloys. At 523 K, the uptake time of RMg₂Ni alloys to reach 90% of the maximum hydrogen storage capacity was 75 s, 34 s, 65 s and 52 s, respectively, compared with 110 s of pristine Mg₂Ni alloy. Therefore, we believed the R-H in the alloys not only improved their thermodynamic properties but also accelerated their hydriding kinetics.     

Diffusion bonding of Zr55Cu30Ni5Al10 bulk metallic glass to Cu with Al as transition layer

In this work we demonstrate the diffusion bonding of Zr₅₅Cu₃₀Ni₅Al₁₀ bulk metallic glass (BMG) to aluminum and copper alloy. The process parameters including temperature, pressure and time are investigated experimentally, and we obtain appropriate ones for accomplishing diffusion bonding of the BMG to aluminum alloy successfully. Then we present a two-step diffusion bonding process to bond the BMG to copper alloy by using aluminum alloy as transition layers, and achieve a five-layer bonded joint of BMG/Al/Cu/Al/BMG. The mechanical properties of the multilayer joint are examined. The hardness of the BMG in the joint is enhanced while the bending strength decreases significantly compared with the as-received BMG. Besides, the crystalline metals alleviate and block the extension of cracks in the BMG, which results in the joint fracturing in an explosion-proof glass manner, dissimilar to rupturing in a catastrophic manner that is always happened in the BMGs. Therefore, diffusion bonding of BMG to crystalline metals is a promising way to extend its application.     

Orientation and growth behavior of CaHfO3 thin films on non-oxide substrates

The growth behavior of CaHfO₃ on (001) Ni and Ge substrates was examined. CaHfO₃ is a perovskite insulator that is suitable for applications as a buffer layer or gate dielectric. The tendency for CaHfO₃ growth on both (001) Ni and (001) Ge substrates is to orient with the CaHfO₃ (200) + (121) planes parallel to the surface, which corresponds to the (110) orientation in the pseudo-cubic geometry. This differs from that of CaHfO₃ on perovskites, such as (001) LaAlO₃, where a pseudo-cube-on-cube orientation is observed.     

The local structure nature for a Ti-based bulk metallic glass

In the present work, the local atomic structures of a Be-containing Ti-based bulk metallic glass (BMG) have been characterized using electron spectrum for chemical analysis and Raman scattering, including directional bonds and medium range order. It might suggest that a coefficient could be extracted from Raman scattering to characterize the glass forming ability (GFA), which could be employed to interpret the enhanced GFA by Be addition of Ti-based BMG. Additionally, compared with the crystallized sample, the glassy sample exhibits larger average bond length and larger content of local bond distortion using Raman scattering.     

Glass forming ability of Fe–Co–Zr–Nd–B alloys and bulk permanent magnets derived from amorphous precursor

The glass forming ability (GFA) and magnetic properties for Fe_48−x Co₂₇Zr₃Nd _x B₂₂ (x = 0–6) alloys were investigated. It was found that the proper addition of Nd (4–5 at.%) was very effective in improving GFA. The as-cast Fe₄₄Co₂₇Zr₃Nd₄B₂₂ and Fe₄₃Co₂₇Zr₃Nd₅B₂₂ alloys exhibited good soft magnetic behavior, while showed hard magnetic property after annealing at 760 °C for 10 min. Bulk permanent magnets were obtained from crystallization of amorphous alloys, which could provide a promising way for the bulk magnet produced by the simple process of copper mold casting and subsequent heat treatment.