Formation and mechanical properties of bulk Cu-Ti-Zr-Ni metallic glasses with high glass forming ability

Bulk amorphous Cu52.5Ti30Zr11.5Ni6 and Cu53.1Ti31.4Zr9.5Ni6 alloys with a high glass forming ability can be quenched into single amorphous rods with a diameter of 5 mm, and exhibit a high fracture strength of 2 212 MPa and 2 184 MPa under compressive condition, respectively. The stress—strain curves show nearly 2% elastic strain limit, yet display no appreciable macroscopic plastic deformation prior to the catastrophic fracture due to highly localized shear bands. The present work shows clearly evidence of molten droplets besides well-developed vein patterns typical of bulk metallic glasses on the fracture surface, suggesting that localized melting induced by adiabatic heating may occur during the final failure event.     

FeCo基大块非晶合金盐雾与电化学腐蚀研究

通过电化学测试方法与中性盐雾腐蚀实验研究Fe24 xCo24-xCr15Mo14C15B6Y2 (X=0, 2, 4, 6, 17)块体非晶合金的耐蚀性。合金在1 mol/L HCl中出现了宽的钝化区,其EIS图谱均由单一容抗弧组成,显示出良好耐蚀性;结合极化曲线与交流阻抗结果分析可得合金耐蚀性随着Co含量的增加先增大后减小,当Co含量为20%时合金耐蚀性最好。利用能谱分析(EDS)与原子力显微镜(AFM)对合金的中性盐雾腐蚀结果进行分析,可知它们的腐蚀产物主要由铁和钴的氧化物以及它们的氯化物组成。同时FeCo基大块非晶合金腐蚀程度随着Co含量的变化而变化,其盐雾腐蚀耐蚀性规律与电化学腐蚀耐蚀性规律一致。     

Role of yttrium in glass formation of Ti-based bulk metallic glasses

Starting with Zr of two different purities, Ti-based bulk metallic glasses (BMGs) with a nominal composition of Ti40Zr25Cu12Ni3Be20 were prepared. The effect of the addition of yttrium at levels of 0.2 at.%, 0.4 at.%, 0.5 at.%, 0.6 at.%, and 1 at.% on the glass forming ability (GFA) of the alloy has been investigated by means of metallography, X-ray diffraction, and differential scanning calorimetry. Experimental data in-dicates that high impurity content dramatically reduces the glass forming ability. Microalloying with 0.5 at.% Y is effective in suppressing the crystalline phase formation and alleviating the detrimental effect of oxygen in the low-purity alloy. On the contrary, in the alloy contain-ing high-purity element, the effective yttrium addition is less than 0.4 at.%. The results indicate that the beneficial effect of the optimum dopants is mainly due to scavenging the oxygen impurity via the formation of innocuous phase.     

Zr基和Ti基块体非晶合金的电化学腐蚀性能(英文)

用电化学方法研究Ti基和Zr基非晶合金及与非晶成分相同的Zr基晶态合金在1mol/LH2SO4和3.5%NaCl溶液中的腐蚀行为。极化曲线测试结果表明:在H2SO4溶液中,Zr基非晶和晶态合金自腐蚀电位比Ti基非晶合金的低;在NaCl溶液中,Zr基晶态合金的自腐蚀电位最低,而且在腐蚀过程中没有发生钝化,然而非晶合金都表现出钝化特性。交流阻抗测试结果表明:在NaCl溶液中非晶合金比晶态合金表现出更好的耐腐蚀性能,但是在H2SO4溶液中并没看到它们之间有明显的区别。表面形貌分析表明:在NaCl溶液中,这2种非晶合金都发生点蚀,而在H2SO4溶液中所有试验合金都表现出类似的特征,试样表面基本保持平整,只是在腐蚀表面的局部区域有一些裂纹出现。     

Ti基非晶复合材料的强韧化机理研究

采用水冷铜坩埚磁悬浮熔炼-铜模吸铸法在真空及高纯氩气保护条件下制备了直径3mm的(Ti_0.5Ni_0.48M_0.02)₈₀Cu₂₀ (M=Fe、Ce、Zr)合金,研究了Fe、Ce、Zr对合金凝固组织中形状记忆晶相析出的变化规律,分析了该合金的室温力学行为与强韧化机理。研究发现,(Ti_0.5Ni_0.48M_0.02)₈₀Cu₂₀ (M=Fe、Ce、Zr)合金铸态结构均为非晶+形状记忆晶相(B2过冷奥氏体和B19_’热致马氏体)的复合结构,其中M=Fe的合金B2相体积分数析出最多,M=Zr的合金B19_,相体积分数最多。在室温压缩过程中,合金均表现出良好的综合力学性能,其中以M=Ce 的合金性能最优,断裂强度,屈服强度,塑性应变分别达到2645Mpa,1150Mpa和12.2%。合金在受压应力断裂后,组织中奥氏体相体积分数减小,马氏体相体积分数增加,同时在屈服后均表现出强烈的加工硬化行为。加工硬化速率和瞬时加工硬化速率随真应变的变化分为三个阶段,合金内部在压应力的作用下B2向B19_,相转变是合金强韧化的主要动力。M=Fe的合金加工硬化速率、平均加工硬化指数、瞬时加工硬化指数最大,加工硬化能力最强,M=Ce的合金次之,M=Zr的合金最弱。     

铁基非晶基涂层的HVOF制备及耐腐蚀性能(英文)

以工业原材料制备的铁基非晶合金、镍铬合金、碳化钨颗粒的混合粉末为原材料,采用高速火焰喷涂技术制备铁基非晶基涂层。通过分析铁基非晶基涂层分别在1 mol/L盐酸、氯化钠、硫酸和氢氧化钠溶液中的动态极化特性,研究其腐蚀阻抗。采用扫描电子显微镜(SEM)分析涂层的腐蚀形貌。结果表明:铁基非晶基涂层具有优良的耐蚀性能,而且在含氯离子溶液中,表现出比304L奥氏体不锈钢更高的腐蚀阻抗。在1 mol/L盐酸溶液中,铁基非晶基涂层的腐蚀电流密度和钝化电流密度分别为132.0μA/cm2和9.0 mA/cm2,在1 mol/L氯化钠溶液中分别为2.5μA/cm2和2.3 mA/cm2,且表现出一个宽的自钝化区间。其优异的耐蚀性能表明铁基非晶基粉末可以作为一种耐腐蚀、耐磨损的工程材料。     

Preparation and properties of borate glass coatings on Ti-based alloy substrates

A series of BaO-La2O3-B2O3 （BLB） glass coats on the Ti-based alloy substrates were developed at different temperatures for different times. The BLB glasses were analyzed by differential thermal analysis （DTA） and thermal mechanical analysis （TMA） to determine the crystallization temperature and coefficients of thermal expansion （CETs） of the glass. The tensile strength and microstructure of the glass coats were analyzed and the effects of the coating condition on the tensile strength and microstructure were discussed. The results show that the CETs of the borate glass at different temperatures match with those of Ti-based alloy, and the difference between the borate glass and Ti-based alloy at each temperature is below 5%. The spreading area in N2 atmosphere is much larger than that in air atmosphere, indicating that N2 atmosphere is helpful for the wetting of borate glass to Ti-based alloy. The tensile strength of the glass coats can reach as high as 28.42 MPa, meeting the requirements for the coat binder. With the increase of coating time, the tensile strength of coats increases firstly while then decreases. The coat prepared at 730 ℃ for 30 min is fairly smooth and complete, while the other coats contain lots of defects such as large or small uncoated region. It is believed that the coating temperature of 730℃ and coating time of 30 min are the proper coating conditions to prepare BLB glass coats.     

Synthesis,properties and XPS analysis of Cu-,Ni-,Ti-based metallic glasses

Metallic glasses（MG）represent an interesting group of materials as they possess outstanding physical,chemical and mechanical properties compared to their crystalline counterparts.This paper reviews the synergistic influence of Ni and Nb elements on thermal stability of supercooled liquid and corrosion resistance of as-cast Cu-Zr（Hf）-Ti-Ni-Nb bulk metallic glasses（BMGs）.Additionally,in-situ second phase reinforced Cu-based BMG composites with high corrosion resistance and excellent mechanical properties are investigated.On the other hand,this paper reports the development of ultra-high corrosion resistant Ni-based metallic glasses at high temperatures for their potential applications.Corrosion resistance and XPS analysis of the Nifree Ti-based BMG are also introduced.     

Effect of processing parameters on the microstructures and corrosion behaviour of high‐velocity oxy‐fuel (HVOF) sprayed Fe‐based amorphous metallic coatings

A FeCrMoMnWBCSi amorphous metallic coating was prepared by using high‐velocity oxy‐fuel spray. The influence of processing parameters on microstructure, porosity level, amorphous phase fraction and corrosion behaviour of the coatings was characterised by scanning electron microscopy, X‐ray diffraction, differential scanning calorimeter and electrochemical methods. The results indicated that the microstructures of the coatings were sensitive to the spray parameters considerably. Porosity and unmelted particle proportion decreased with the oxygen/fuel (O/F) ratio and increased with the powder feed rate. The trend of oxides content was opposite to the porosity and unmelted particle proportion. The coatings obtained with higher O/F ratio and lower powder feed rate exhibited higher hardness. The low coating hardness was mainly due to the high porosity especially when the porosity was higher than 1.21%. The spraying parameters strongly affected the amorphous phase fraction. There was a critical passive current density for balancing the porosity and the amorphous phase fraction. Corrosion resistance is dominant by the amorphous phase fraction when the porosity is less than 1.21%, while by porosity when it is higher than that. Open‐circuit potential, potentiodynamic polarisation and electrochemical impedance spectroscopy results showed that the coatings obtained with the O/F ratio of 4.2 and the powder feed rate of 40 g/min exhibiting the best corrosion resistance in 1 wt% sodium chloride solution.     

Nd对块体Mg-Cu-Y-Nd非晶合金玻璃形成能力的影响

在非真空熔炼条件下采用工业纯原材料和负压铜模吸铸法制备Mg65Cu25Y10-xNdx(x=0,2,4,6,8,10)棒状试样,利用差示扫描量热(DSC)和X射线衍射(XRD)等方法分析Nd对Mg-Cu-Y-Nd非晶合金玻璃形成能力的影响。结果表明:Nd的含量(x)为0,4,6成分的合金试样具有完全非晶态组织,且x=4时具有最大的玻璃形成能力,其约化玻璃转变温度(Trg)为0.592,过冷液相区宽度(ΔTx)高达66 K;当x为2,8,10时,由于合金成分明显偏离共晶成分,玻璃形成能力降低,试样只含有少量非晶,且主要呈晶体组织特征。     

Dynamic mechanical behavior of a Zr-based bulk metallic glass during glass transition and crystallization

The dynamic mechanical behaviors of the Zr41Ti14Cu12.5Ni8Be22.5Fe2 bulk metallic glass (BMG) during continuous heating at a constant rate were investigated. The glass transition and crystallization of the Zr-based BMG were thus characterized by the measurements of storage modulus E and internal friction Q-1. It was found that the variations of these dynamic mechanical quantifies with temperature were interre-lated and were well in agreement with the DSC trace obtained at the same heating rate. The origin of the first peak in the internal friction curve was closely related to the dynamic glass transition and subsequent primary crystallization. Moreover, it can be well described by a physical model, which can characterize atomic mobility and mechanical response of disordered condense materials. In comparison with the DSC trace, the relative position of the first internal friction peak of the BMG was found to be dependent on its thermal stability against crys-tallization.     

Oxidation induced ductility enhancement of Zr based metallic glass ribbons in vicinity of glass transition temperature

Zr-based metallic glasses(MGs)possess a wide supercooled liquid region,which gives a wide processing window for superplastic forming to make microdevices with demanding size accuracy and surface finishing.The existence of oxygen may have an influence on the thermoplastic deformation process.Therefore,the effect of oxidation on the mechanical behavior of the MGs in the vicinity of glass transition temperature is of great significance for practical forming of MG components.In the present study,the effect of oxidation on tensile properties of Zr50Cu40Al10 metallic glass was investigated.The tested samples were characterized by XRD and SEM analysis.For the samples tested in air,the strength decreases 187 MPa,61 MPa and 59 MPa and the ductility increases 0.31,0.36,and 0.77 at 420℃,430℃,and 440℃,respectively,compared with those tested in flowing argon.ZrO₂ preferentially formed during the tensile testing at 420℃,and both ZrO₂ and Al₂O₃ oxides formed at 430℃.The dilution of Zr elements in the remaining amorphous matrix caused by preferential oxidation on the surface layer attributes to the decrease in strength and enhancement in ductility of the Zr₅₀Cu₄₀Al₁₀ metallic glasses.     

镍基非晶合金涂层的制备与腐蚀性能

用气体雾化法制备了Ni53Nb20Ti10Zr6Co6Cu3非晶合金粉末,将粒度小于25μm的非晶粉末用动力金属喷涂工艺制备了非晶涂层．研究表明,非晶涂层厚度约500μm,涂层的空隙率随喷涂温度和沉积率的增加而减少．涂层腐蚀性能的评价选用1kmol／m^3 HCl水溶液,动电位极化曲线测量表明,随着空隙率的减少,涂层呈现出与非晶合金相当的优良耐蚀性能．     

粉末非晶硅制备及其气体氢化和电化学储氢性能研究

以Li13Si4为原料采用化学去锂化法制备了具有层状结构的非晶硅(α-Si)粉体并对α-Si进行球磨改性,研究了改性前后α-Si在H2中的氢化行为以及氢化处理对α-Si电极在质子传导离子液体中的电化学储氢性能影响。研究结果表明,球磨能明显减小α-Si粉体的颗粒尺寸,但易引入Fe和Cr金属杂质并形成Fe2Si与CrSi2。氢化时α-Si逐渐发生晶化,当氢化时间不少于8 h时,α-Si基本完全晶化,氢化后的SiHx结构由SiH、SiH2和SiH3三种成键模式组成。球磨改性有助于增加α-Si的初始吸氢量,随氢化时间延长,α-Si的吸氢量逐渐增大,其中经球磨和氢化2、5、8和58 h后的α-Si吸氢量分别达到(质量分数)0.38%、0.76%、0.91%和3.8%,其吸氢速率比较缓慢。α-Si电极在质子型离子液体中具有电化学吸放氢反应活性,但其放电容量偏低(42~163 mAh/g),其中球磨和氢化8 h的α-Si经20次充放电后具有最大放电容量163 mAh/g。球磨改性和适当的氢化处理(8 h)有利于提高α-Si电极的放电容量。     

Ti基非晶及准纳米晶材料制备技术研究

用Al、B取代Ti50Ni15Cu25Sn3Be7中有毒的Be元素,采用真空甩带及铜模吸铸法制备名义成分为Ti50Ni15Cu25-Sn3Al6.9B0.1的非晶合金。对制得的合金经热处理制备准纳米晶体。采用SEM观察组织及晶粒大小。XRD分析结果表明,铜模吸铸法所制得的合金为晶态加少量非晶。DTA分析表明,合金存在三个相变转变点,转变温度分别为Te1=350℃、Te2=430℃和Te3=510℃。合金经800℃油淬10min、350℃回火12h后晶粒细化,晶粒尺寸在1μm以下,其中析出相的晶粒尺寸已是准纳米级或纳米级尺度。回火24h后晶粒明显长大,晶粒平均尺寸在10μm左右。     

3D printing of crack-free high strength Zr-based bulk metallic glass composite by selective laser melting

3D printing of crack-free bulk metallic glasses remains challenge due to the generation of huge thermal stress during the selective laser melting and their intrinsic brittleness. Herein, Zr₅₅Cu₃₀Ni₅Al₁₀ system was selected and 3D printed by selective laser melting technique. The results indicated that bulk metallic glassy composite comprises a large fraction (about 83%) of amorphous phase and minor fraction of intermetallic compounds with free of cracks were successfully fabricated. The 3D printed metallic glassy composite exhibited high strength over 1500 MPa. Experiment combined with finite-element-method simulation not only revealed the mechanism of crystallization at heat affected zones, but demonstrated that low thermal stress reduce the risk of micro-cracks generation and fracture toughness plays a crucial role in suppression the crack propagation during selective laser melting process.     

Design of Bulk metallic glasses with high glass forming ability and enhancement of plasticity in metallic glass matrix composites: A review

To overcome some of the limits of existing metallic alloys, a new alloy design concept has been introduced recently in order to control the crystallinity, i.e. to utilize crystalline, quasicrystalline, and amorphous structures. In particular, bulk metallic glasses (BMGs) receive great attention because of their unique properties due to their different atomic configuration. Recently, significant progress in enhancing glass forming ability (GFA) has led to the fabrication of BMGs having potential for application as structural and functional materials. Moreover, successful design of BMG matrix composite microstructure suggests that the plasticity of BMGs can be controlled properly. In this review article, we introduce recent research results on the design of BMGs with high GFA and on the enhancement of plasticity in metallic glass matrix composites.     

合金微结构的调整对铁基块体金属玻璃室温塑性的影响(英文)

报道一种新奇的现象,即随着Fe75Mo5P10C8.3B1.7块体金属玻璃的直径从1.5mm增加到2.0mm,其室温压缩塑性反而从0.5%增加到1.8%。这主要归因于随着铁基块体金属玻璃样品直径的增加,原位形成了零星的α-Fe枝晶相,这种在边缘化的块体金属玻璃中出现的异质结构是提高当前铁基块体金属玻璃室温塑性的主要原因。     

Zr基块体非晶合金的微塑性成形性能

采用自行研制的微成形系统进行热压缩实验,分别研究成形温度、成形时间和冲头速度等对尺寸为d1 mm×1.5 mm的Zr41.2Ti13.8Cu12.5Ni10Be22.5块体非晶合金(Vit.1)在过冷液相区微塑性成形性能的影响规律。进一步研究了不同坯料尺寸对Vit.1块体非晶合金在过冷液相区超塑性成形性能的影响程度,结果表明流动应力随坯料尺寸的减小而降低。在此基础上,利用闭式模锻方法成形了分度圆直径为d1 mm的微型齿轮,采用SEM观察成形件的表面形貌,结果表明采用微成形方法可以获得尺寸精度较高的Vit.1块体非晶合金微型齿轮。     

Effect of carbon addition on microstructure and mechanical properties of Ti-based bulk metallic glass forming alloys

A kind of novel Ti-based composites was developed by introducing different amounts of carbon element to the Ti50 Cu23 Ni20 Sn7 bulk metallic glass forming alloys. The thermal stability and microstructural evolution of the composites were investigated. Room temperature compression tests reveal that the composite samples with 1% and 3% （mass fraction） carbon additions have higher fracture strength and obvious plastic strain of 2 195 MPa, 3. 1% and 1 913 MPa, 1.3% respectively, compared with those of the corresponding carbon-free Ti50 Ni20 Cu23 Sn7 alloys. The deformation mechanisms of the composites with improved mechanical properties were also discussed.