Quaternary Ti–Zr–Be–Ni bulk metallic glasses with large glass-forming ability

The glass-forming ability (GFA) of Ti–Zr–Be ternary alloys is dramatically improved by partially replacing Be with Ni. Centimeter-scale fully amorphous samples can be obtained in a wide Ni content range of 4 at.%–12 at.%. In particular, some of the developed Ti–Zr–Be–Ni alloys exhibit a critical diameter up to 20 mm, which is larger than that of other quaternary Ti-based bulk metallic glasses (BMGs). Moreover, Ni addition also enhances the yield strength and compressive plastic strain of Ti–Zr–Be alloys obviously. Based on the experimental results, the effect of substituting elements addition on the glass-forming ability of Ti–Zr–Be alloys has been systematically investigated and an empirical composition design method for the development of novel Ti-based BMGs with large GFA has been proposed.     

Evaluation of glass forming ability in binary and ternary metallic alloy systems – an application of thermodynamic phase diagram calculations

Abstract

The glass forming ability (GFA) of a wide range of binary and ternary alloy systems (Au–Si, Pd–Si, Ti–Be, Zr–Be, Hf–Be, Cu–Ti, Co–Zr, Ni–Zr, Cu–Zr, Ni–P, Pd–P, Ni–Pd–P, Cu–Pd–P, Co–Ti–Zr, Zr–Be–Hf, Ti–Be–Hf, Ti–Be–Zr) was calculated using a combined thermodynamic and kinetic approach. There is good agreement between the predicted glass forming ranges and those experimentally observed. By using this combined approach it has also proved possible to estimate critical cooling rates for phases not observed in the equilibrium phase diagram. A significant advantage of the approach is that, for multicomponent alloys, the melting temperatures and thermodynamic input parameters for the kinetic equations are derived using the constituent binary thermodynamic phase diagram calculations and, therefore, it has the potential to predict GFA in multicomponent systems using information from mainly binary systems.

MST/788     

具有大过冷液相温度区间的Cu基大块非晶合金的制备和机械性能

利用铜模铸造方法制备了具有大过冷液相温度区间的Cu-Zr-Ti-Ni系高强度Cu基大块非晶合金,对于Cu55Zr55Ti15Ni5合金,最大直径达5mm.过冷液相区温度范围ΔTx达45.48～70.98 K.Cu基玻璃合金棒表现出非常高的机械性能和明显的塑性,对于Cu50Zr25Ti15Ni10、Cu55Zr25Ti15Ni5和Cu54Zr22Ti18Ni6合金,压缩断裂强度分别达2155MPa、2026MPa和1904MPa,维氏硬度分别达674、678和685.加入Co元素扩大了CuZr-Ti-Ni系合金的ΔTx,Cu50Zr22Ti18Ni6Co4合金的ΔTx高达74.5K.     

微量Al添加对铜基大块非晶合金性能的影响

为了进一步提高铜基大块非晶合金的玻璃形成能力及力学性能,采用添加微量Al元素的方法对块体非晶合金Cu52.5Ti30Zr11.5Ni6进行了成分优化.热分析与X射线衍射结果显示,随着微量Al的添加,液相线温度从非晶合金Cu52.5Ti30Zr11.5Ni6的1150 K逐步降低到Cu50.5Ti30Zr11.5Ni6Al2的1134 K,临界直径相应的从5 mm提高到6 mm.大块非晶Cu50.5Ti30Zr11.5Ni6Al2的压缩断裂强度达到2286 MPa,比经典的铜基非晶合金Cu47Ti34Zr11Ni8提高约100 MPa,表明微量Al的添加在有效提高玻璃形成能力的同时,强度也略有提高.     

Zr基大块非晶合金成分的等电子浓度和等原子尺寸判据

制备了6种合金Zr65.5Al5.6Ni6.5Cu22.4,Zr65.3Al6.5Ni8.2Cu20,Zr65Al7.5Ni10Cu7.5,Zr64.8Al8.3Ni11.4Cu5.5,Zr64.5Al9.2Ni13.2Cu13.1和Zr63.8Al11.4Ni17.2Cu7.6,共晶成分位于合金Zr64.5Al9.2Ni13.2Cu13.1和合金Zr63.8Al11.4Ni17.2Cu7.6的成分之间，这6种合金均显示了非晶相的形成和较宽的过冷液相区范围△Tx值，以及较大的约化玻璃转变温度Trg值，除合金Zr63.8Al11.4Ni17.2Cu7.6的△Tx值为87K外，其余5种成分合金的△Tx值均在97K以上，最宽的达105K，表明这6种合金是一个具有大玻璃形成能力和高热稳定性的非晶合金系列，合金Zr63.8Al11.4Ni17.2Cu7.6是6种合金中玻璃表成能力和热稳定性最高的，其Tg，Tx和Trg值最高，Inoue非晶合金Zr65Al7.5Ni10Cu17.5并不是最佳非晶成分，提出以等电子浓度和等原子尺寸规律作为设计大块非晶合金成分的判据。     

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.     

Roles of alloying additions on local structure and glass-forming ability of Cu–Zr metallic glasses

To identify the structural role of alloying element M (M = Ti, Ga, Co, Fe) on the glass-forming ability (GFA) of Cu₅₀Zr₅₀ base alloy, the atomic structures of the binary and ternary metallic glasses were examined by extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS curve-fitting analysis indicates that the main structural difference among the metallic glasses is in the atomic packing density of Cu-centered clusters. The relative shortening of the Cu–M distance is closely related to the heat of mixing between Cu and M: the more negative the heat of mixing, the larger is the shortening of the Cu–M distance. Based on a systematic analysis of the component properties and GFA data for Cu–Zr based alloys, it is suggested that alloying elements that bring a more uniform distribution of atomic size and possess strong chemical interactions with the main components should be selected in developing large-size bulk metallic glasses.     

Preparation of Cu-based Bulk Metallic Glass Matrix Composites

Cu47Ti34Zr11Ni8 bulk metallic glass （BMG） matrix composites containing in situ formed TiC particles and 5-TiCu dendrite phase were developed by copper mold cast. The thermal stability and microstructure of the composites are investigated. Room temperature compression tests reveal that the composite samples exhibit higher fracture strength and distinct plastic strain of 0.2%-0.5%, comparing with that of the corresponding Cu47Ti34Zr11Ni8 monolithic BMG.     

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.     

Co47.6Fe20.4B21.9Si5.1Nb5-xZrx(x=0~5)合金的非晶形成能力和磁性能

采用铜模吸铸法制备了直径d为2~5mm的Co_(47.6)Fe_(20.4)B_(21.9)Si_(5.1)Nb_(5-x)Zr_x(x=0~5)合金。利用X射线衍射(XRD)、差示扫描量热仪(DSC)、振动样品磁强计(VSM)和显微硬度计分析合金的非晶形成能力(GFA)、磁性能及显微硬度。结果表明:该合金体系具有较好的GFA,随着Zr含量的增加,其GFA呈逐渐降低的趋势。Zr含量为0~2%(原子分数)时,能制得d为3mm的非晶合金;Zr含量为0~3%(原子分数)时,可制得d为2mm的非晶合金。直径2mm的棒状非晶合金(Zr含量为0~3%(原子分数))表现为明显的软磁性,饱和磁化强度Ms趋于一定值。该体系非晶合金均具有很高的显微硬度,Zr含量为3%(原子分数)时达到1420HV。     

钎焊工艺参数对C/C复合材料/Cu/Mo/TC4钎焊接头微观组织的影响

在钎焊温度为820～940℃,钎焊时间为1～30min的条件下,采用TiZrNiCu钎料、Cu/Mo复合中间层对C/C复合材料和TC4进行了钎焊实验。利用扫描电镜及能谱仪对接头的界面组织进行了研究。结果表明:在较低工艺参数下,Cu/C/C复合材料界面结构为Cu/Cu51Zr14/Ti2(Cu,Ni)+Ti(Cu,Ni)+TiCu+Cu2TiZr/TiC/C/C复合材料。随着工艺参数的提高,TiCu和Cu2TiZr反应相逐渐消失,Ti(Cu,Ni)2新相生成,此时的界面结构为Cu/Cu51Zr14/Ti2(Cu,Ni)+Ti(Cu,Ni)+Ti(Cu,Ni)2/TiC/C/C复合材料。钎焊工艺参数较高时界面结构为Cu/Cu51Zr14/Cu(s.s)+Ti(Cu,Ni)2/TiC/C/C复合材料。随着钎焊温度的增加以及保温时间的延长,界面反应层Cu51Zr14和TiC反应层厚度增加。     

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.     

Precipitation hardening of Cu – Ti – Zr alloys

Abstract

The influence of age hardening temperature and time on the hardness, tensile properties, electrical conductivity, and microstructure of Cu – 4Ti – 0.1Zr and Cu – 3Ti – 0.1Zr alloys has been investigated. The resulting microstructure of these alloys suggests that zirconium addition prohibited the formation of compositional modulations in the solution treated condition. These alloys exhibited maximum hardness and strength on peak aging at 450°C for 24 h by the formation of a coherent and metastable Cu₄Ti phase (β') in modulated structure while overaging occurred by the formation of equilibrium phase β-Cu₃Ti. The electrical conductivity of both the alloys increased moderately on aging. Unlike in an earlier study of binary Cu – Ti and some ternary Cu – Ti – X alloys, overaging did not cause any discontinuous precipitation in the Cu – Ti – Zr alloys investigated. Modulated structure formed on peak aging persisted on prolonged aging at 450°C for 80 h or at 500°C for 8 h.     

Enhanced glass forming ability of Fe-based alloys with minor additions

Minor Fe and Yof Fe_71.2B₂₄Y_4.8 bulk metallic glass (BMG) are replaced by Ni, Nd, and Ge, respectively, and glass-forming ability (GFA) influenced by these similar element substitutions are studied. Except Ge, Ni and Nd can both improve the critical diameter of base BMG from 2 to 3 mm. Therefore, substitutions with chemical similar elements are more effective on GFA enhancement than those with atom size similar elements.     

Ductilization of Ni_3Al by Alloying with Substitutional Elements

This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binaryalloys with hypostoichiometric compositions show appreciable ductility at room temperature whenthe samples are prepared by recrystallization annealing after cold pressing,although the alloys withstoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons withhypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can beseen in melt-spun ribbons with a hyperstoichiometric composition.The ductility inhypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition ofternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improvesductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists offine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac-ture.No APD was observed in the melt-spun ribbons of these ternary alloys.     

Phenomena of nanotube nucleation and growth on new ternary titanium alloys

Ti-30Nb-xZr and Ti-30Ta-xNb alloys have been investigated using various methods of surface nanotube formation. Ternary Ti-30Nb-xZr (x = 3 and 15 wt%) and Ti-30Ta-xNb (x = 3 and 15 wt%) alloys were prepared by using high-purity sponge Ti (Grade 4, G&S Titanium, USA), Ta, Zr and Nb spheres. The two groups of ternary Ti alloys were prepared using a vacuum arc melting furnace. Nanotube formation was carried out with a conventional three-electrode configuration with the Ti alloy specimen, a platinum counterelectrode, and a saturated calomel (SCE) reference electrode. Experiments were performed in 1 M H3PO4 with small additions of NaF (0.1-0.8 wt%), using a potentiostat. Nanotubes formed on the surfaces of the two ternary Ti alloys were examined by field emission scanning electron microscopy, EDS and XRD. The Ti-30Ta-xZr alloys had microstructure with entirely needle-like constituents; the thickness of the needle-like alpha-phase increased as the Zr content increased. The Ti-30Nb-xZr alloys had equiaxed microstructures of the beta-phase, and increasing amounts of the needle-like alpha phase appeared at the grain boundaries of the beta-phase as the Zr content increased. The nanotubes were nucleated and grew mainly on the beta phase for the Ti-30Ta-3Zr and Ti-30Nb-3Zr alloys, which had nanotubes with uniform shape, but the nanotubes were nucleated at the alpha phase for the Ti-30Ta-15Zr and Ti-30Nb-15Zr alloys, which had nanotubes with irregular shape and diameters of two sizes. The diameter and depth of the nanotubes could be controlled, depending upon the alloy composition and composition of the surface oxide films (TiO2, Nb2O5, Ta2O5, and ZrO2). It is concluded that this research that selection of the appropriate alloying element can allow significant control of the nanotopography of these Ti alloy surfaces and that it is possible to control the surface nanotube size to promote long-term osseointegration for clinical dental or orthopedic use.     

Short communication Effects of tantalum addition on transformation behaviour of (Ni51 Ti49 )1-x Tax and Ni50 Ti50-y Tay shape memory alloys

Abstract

The effect of Ta content on the transformation characteristics of Ni–Ti–Ta ternary alloys has been studied. In (Ni₅₁ Ti₄₉ )_1-x Ta_x type alloys, the phase transformation temperatures increase with Ta content, especially when the Ta content is less than 4 at.-%. In Ni₅₀ Ti_50-x Ta_x type alloys, the phase transformation temperatures decrease as Ta content increases. The martensite start temperature is less sensitive to changes in Ni content in ternary Ni–Ti–Ta alloys than that in Ni–Ti binary alloys. The phase transformation temperatures of Ni–Ti–Ta ternary alloys are mainly controlled by the Ni/Ti ratio in the Ni–Ti matrix.     

Joining of Zirconia and Ti-6Al-4V Using a Ti-based Amorphous Filler

Polycrystalline ZrO2-3 mol.%Y2O3 was brazed to Ti-6Al-4V by using a Ti47Zr28Cu14Ni11(at.%) amorphous ribbon at 1123-1273 K in a high vacuum. The influences of brazing temperature on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be described as ZrO2/TiO+TiO2+Cu2Ti4O+Ni2Ti4O/α-Ti+(Ti,Zr)2(Cu,Ni) eutectic/acicular Widmanst¨aten structure/Ti-6Al-4V alloy. With the increase in the brazing temperature, the thickness of the TiO+TiO2+Cu2Ti4O+Ni2Ti4O layer reduced, the content of the α-Ti+(Ti,Zr)2(Cu,Ni) eutectic phase decreased, while that of the coarse α-Ti phase gradually increased. The shear strength of the joints did not show a close relationship with the thickness of the TiO+TiO2+Cu2Ti4O+Ni2Ti4O layer. However, when the coarse (Ti,Zr)2(Cu,Ni) phase was non-uniformly distributed in the α-Ti phase, or when α-Ti solely situated at the center of the joint, forming a coarse block or even connecting into a continuous strip, the shear strength greatly decreased.     

激光诱导燃烧合成Zr-Ti-Al-Ni合金

根据等电子浓度和等原子尺寸判据设计了四种Zr Ti-Al-Ni系合金,并用激光诱导燃烧合成的方法制备了材料研究发现,其合成产物主要由金属间化合物和Ti/Zr固溶体组成,在成分Zr55Ti1o 8Al171Ni17 1和Zr50Ti21 6Al14 2Ni14 2中还出现了非晶相.合成产物的硬度和摩擦磨损特性与相组成有密切的关系,非晶含量越大,合金硬度值越低,平均摩擦系数越高.