锆基大块非晶在HCl溶液中的耐腐蚀性研究

利用CHI660B型电化学工作站研究了4种不同成分（Zr55Al10Ni5Cu30，Zr60Al15Ni25，Zr65Al10Ni10Cu15，Xr52．5Al0Ni10Cu15Be12．5）的锆基非晶态合金以及其中两种成分（Zr65Al10Ni10Cu15，Zr52．5Al10Ni10Cu15Be12．5）的晶态合金在2．5mol／L的HCl溶液中的腐蚀行为。通过Tafel曲线的测试结果表明，非晶合金的耐腐蚀性能与其成分有很大的关系，这4种非晶合金试样的耐腐蚀性由强到弱的顺序依次为Zr60Al15Ni25〉Zr65Al10Ni10CU15〉Zr52．5Al10Ni10Cu15Be12．5〉Zr55Al10Ni5Cu30。两种成分的非晶态合金与其对应成分的晶态试样相比，非晶态合金具有较低的腐蚀电流，显示出较好的耐腐蚀性。最后，根据电化学腐蚀原理，从合金的微观结构、化学成分以及腐蚀介质的性质3个方面探讨了影响合金耐腐蚀性的因素。     

High-strength Zr-based bulk amorphous alloys containing nanocrystalline and nanoquasicrystalline particles

Abstract

It was recently found that the addition of special elements leading to the deviation from the three empirical rules for the achievement of high glass-forming ability causes new mixed structures consisting of the amorphous phase containing nanoscale compound or quasicrystal particles in Zr–Al–Ni–Cu–M (M ? Ag, Pd, Au, Pt or Nb) bulk alloys prepared by the copper mold casting and squeeze casting methods. In addition, the mechanical strength and ductility of the nonequilibrium phase bulk alloys are significantly improved by the formation of the nanostructures as compared with the corresponding amorphous single phase alloys. The composition ranges, formation factors, preparation processes, unique microstructures and improved mechanical properties of the nanocrystalline and nanoquasicrystalline Zr-based bulk alloys are reviewed on the basis of our recent results reported over the last two years. The success of synthesizing the novel nonequilibrium, high-strength bulk alloys with good mechanical properties is significant for the future progress of basic science and engineering. © 2000 Published by Elsevier Science Ltd.     

Formation of amorphous electrodeposited Ni-W alloys and their nanocrystallization

Ni-W alloys containing about 5 to 30 at. % W were prepared by electrodeposition. The plating bath for the electrodeposition contained nickel sulfate, citric acid, sodium tungstate and ammonium chloride, and was operated at various bath concentrations and conditions of electrolysis. X-ray diffraction peaks of the deposited alloys broadened with increasing tungsten content and an amorphous pattern appeared at a tungsten content of about 20 at. %. Nanocrystallization behavior of the amorphous Ni-25.0 at. % W alloy has been studied by X-ray diffraction, high resolution transmission electron microscopy and small angle X-ray scattering. The Hall-Petch strengthening mechanism was observed for the hardness extending to a finest grain size of about 10 nm. When the grain size was less than about 10 nm, decrease of the hardness was observed. This decrease may be due to the significant increase of the intercrystalline volume fraction, especially the fraction associated with the triple junction.     

Cast bulk ZrTiAlCuNi amorphous alloys

Cylindrical bulk amorphous samples with diameters up to 10 mm have been prepared by casting ZrTiAlCuNi alloys in a copper mould. In order to rank glass-forming ability as a function of alloy composition, alloys were also cast into wedge-shaped moulds; to a first approximation, the thickness of the amorphous region obtained can be taken as an indication of glass-forming ability. The compositions which lead to the production of bulk glasses all have reduced glass transition temperatures in excess of 0.65 and the extremely high glass-forming ability of these compositions is discussed. We suggest that both the Al and Ti contents are determining factors for the production of bulk amorphous samples and these are believed to reduce the driving force for, and hence the rate of, crystallisation. These amorphous alloys have been found to display high thermal stability and can be annealed for several minutes in the supercooled liquid region. They are ductile at room temperature and have a high value of yield stress.     

纳米晶的形成对FeCSiBPCu非晶合金软磁性能的影响

研究了Fe76-xC7.0Si3.3B5.0P8.7Cux(x=0、0.3%或0.7%(原子分数))非晶合金中Cu的添加及纳米晶的形成对其软磁性能的影响,对合金的微观结构进行了X射线衍射实验和高分辨透射电镜观察,对合金的热稳定性和晶化激活能进行了测量和分析。结果表明,该合金退火之后的饱和磁化强度与合金中α-Fe纳米晶粒的密度和大小密切相关。Cu的添加可以影响合金的非晶形成能力、热稳定性和晶化激活能,添加少量的Cu(少于0.3%(原子分数))可以有效地提高合金的非晶形成能力,抑制退火过程中α-Fe纳米晶粒的析出,增强合金的热稳定性,而当Cu的添加量达到0.7%(原子分数)时可以降低合金的晶化激活能,促进α-Fe纳米晶粒的形核,提高α-Fe纳米晶粒的密度,使合金的饱和磁化强度达到1.79T。     

Zr-Al-Ni-Co块体非晶合金的成分设计

选择Zr-Al-Ni-Co合金系为研究体系,以等电子浓度和等原子尺寸为判据设计8种合金,采用吸铸法制备了直径为3 mm的合金棒,XRD结果表明了在等电子浓度面和等原子尺寸面交线上存在着一个较大范围的块体非晶合金形成区域.能够形成块体非晶合金的7种合金,具有相近的约化玻璃转变温度Trg值,最大达到0.589;它们的玻璃转变温度Tg值略有差异,且从三元Zr-Al-Co一侧至三元Zr-Al-Ni一侧,其值逐渐减小,最高Tg=713 K.将Zr-Al-Ni-Co合金系与用相同方法设计的块体非晶合金Zr-Al-Ni-Cu和Zr-Al-Ni-Fe体系进行了比较.     

Compressive fracture behavior of Cu-based bulk amorphous alloys

The mechanical properties of newly developed Cu_52.5 − xTi₃₀Zr_11.5Ni₆Al_x (x = 0, 1, 1.5, 2 at.%) bulk amorphous alloys were investigated under compressive condition. They exhibit high fracture strength of 2212 MPa, 2165 MPa, 2209 MPa and 2286 MPa, respectively. Three distinct vein patterns corresponding to the different zones can be observed on the fracture surfaces of the samples. Fracture propagation along two different directions and formation of striated vein patterns may contribute to the higher compressive fracture strength of the tested Cu-based bulk amorphous alloys.     

块体非晶合金及其涂层的电化学行为

采用铜模吸铸法制备了直径为2mm的Fe58Cr12Mo7C15B6Y2和直径为4mm的Fe55Cr12Mo10Cu2C13B6Y2两种块体非晶合金.利用电弧喷涂方法将相同成分的粉芯丝材喷涂在Q235基板上.对涂层进行的结构分析表明,涂层由非晶相和晶化相共同组成,涂层中含有＜2%的孔隙.涂层和块体非晶合金电化学腐蚀研究结果表明,块体非晶合金在极化过程中发生了多次钝化现象,涂层在电化学反应过程中钝化现象比较短暂.非晶样品和涂层之间电化学性能的差异与涂层成分和结构的不均匀性有关.     

大块非晶合金的性能、制备及应用

综述了大块非晶合金的性能、制备方法及应用，对比了吸铸法制备的棒状Zr41.2Ti13.8Cu12.5Ni10Be22.5,Zr57Cu20Al10Ni8Ti5,Zr52.5Ti5Cu17.9Ni14.6Al10(原子分数)大块非晶样品的过冷温度区间宽度(△Tx)，给出了3种大块非晶合金系列的热稳定性参数Tg、Tx及△Tx，提出了大块非晶合金领域存在的问题及发展方向．     

Effect of crystalline precipitations on the mechanical behavior of bulk glass forming Zr-based alloys

Production of bulk amorphous Zr-based alloys with a significant supercooled liquid region was carried out by die casting into a copper mold. Fully amorphous and partially crystalline samples were prepared. The microstructure was analyzed by X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM), and chemical analysis with special emphasis on the size and composition of the crystallites. The mechanical behavior was investigated by constant compression rate tests at strain rates from 1 x 10⁻⁴ s⁻¹ to 3 x 10⁻⁴ s⁻¹ at room temperature using cylindrical specimens of 3 mm diameter and 6 mm height. Independent of the chosen composition the samples exhibit relatively low Young's moduli of about 70 GPa, flow stresses around 2 GPa, and elastic strains of up to 3%. Specimens with a high volume fraction of crystalline phases are extremely brittle. In contrast, almost fully amorphous samples show microplasticity up to 1% strain without significant work hardening. A first explanation is given for the influence of crystalline phases upon crack initiation and propagation.     

ZrTiCuNiBe块体非晶合金的热电阻特性及电子结构

为了揭示ZrTiCuNiBe块体非晶合金的物理性能,利用电弧炉熔炼及铜模快速铸造的方法,制备Zr41.2Ti13.8Cu12.5Ni10Be22.5块状非晶合金.通过测量热电阻系数和电子能谱,研究了块体非晶合金的热电阻特性和电子结构.研究表明:电阻率随着温度升高而降低,紧临晶化前未出现电阻率极大现象;块体非晶态合金与晶态纯金属相比,锆的电子结合能不发生变化,其余元素电子结构明显改变.     

Synthesis and characterization of bulk amorphous/amorphous composite alloys through powder metallurgy route

In the present study, amorphous Ni₆₀Nb₂₀Zr₂₀ and Ti₅₀Cu₂₈Ni₁₅Sn₇ alloy powders were synthesized separately using a mechanical alloying (MA) technique. The dual-amorphous-phased (Ti₅₀Cu₂₈Ni₁₅Sn₇)_100−x (Ni₆₀Nb₂₀Zr₂₀) _x (x = 0, 10, 20, and 30 vol%) powders were prepared by mixing the corresponding amorphous powders. The dual-amorphous-phased powders were then consolidated into bulk amorphous/amorphous composite (BA/AC) alloy discs. The amorphization status of as-prepared powders and bulk BA/AC composite discs was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructure of the BA/AC discs showed that the Ni₆₀Nb₂₀Zr₂₀ phase is distributed homogeneously within the Ti₅₀Cu₂₈Ni₁₅Sn₇ matrix. The (Ti₅₀Cu₂₈Ni₁₅Sn₇)₇₀(Ni₆₀Nb₂₀Zr₂₀)₃₀ BA/AC disc exhibited a relative density of 96.6% and its Vickers microhardness was 726 kg/mm².     

全金属组元铁基块体非晶的制备与性能研究

为了获得良好的玻璃形成能力,通常在铁基非晶合金中添加类金属元素(P、C、B、Si等),但这些铁基非晶合金大多室温塑性很差,且其脆性与其类金属元素的种类、含量以及分布有密切关系,因而本文选取全金属组元铁基非晶合金(Fe_(0.52)Co_(0.3)Ni_(0.18))_(73)Cr_(17)Zr_(10),通过旋淬甩带与铜模喷铸的方法分别制备了条带与块体试样,并采用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、万能试验机等进行了相关性能研究.研究表明:(Fe_(0.52)Co_(0.3)Ni_(0.18))_(73)Cr_(17)Zr_(10)的临界尺寸在1～2 mm,玻璃转变温度为482℃,过冷液相区达到70℃;直径为1 mm的非晶棒材的屈服强度为2 190 MPa,断裂强度达到2 800 MPa,塑性应变量为3.6%.全金属成分中更多的金属-金属键合方式可能是其拥有较好塑性的原因.     

Vibrational dynamics of Zr-based bulk metallic glasses

The vibrational dynamics of some Zr-based bulkmetallic glasses were studied at room temperature in terms of phonon eigen frequencies of longitudinal and transverse modes employing three different approaches proposed by Hubbard-Beeby (HB), Takeno-Goda (TG) and Bhatia-Singh (BS). The well recognized model potential is employed successfully to explain electron-ion interaction in the metallic glass. The present findings of phonon dispersion curve are found to be in fair agreement with available theoretical as well as experimental data. The thermodynamic properties obtained by the HB and TG approaches are found to be much lower than those obtained by the BS approach.     

压力及制备条件对大块非晶合金结构的影响

大块非晶合金又称大块金属玻璃,是一种具有特殊结构与性能的新型金属材料.本文利用同步辐射XRD技术研究了常压和11.6GPa压力下Zr41.2Ti13.8Cu12.5Ni10Be22.5大块非晶合金结构以及0～50GPa压力范围内Fe60Co10Zr8Mo5Nb2B15大块非晶形成合金结构特征的演变.另外,利用同步辐射XRD研究了冲击波处理和水淬条件下制备的Zr41.2Ti13.8Cu12.5Ni10Be22.5大块非晶合金微观原子构型的差异.研究表明,压力与制备条件对大块非晶合金的结构均有一定影响,本研究对深入了解大块非晶合金结构本质及进一步开发该类材料具有重要理论和现实意义.     

Mechanical behavior of Zr-based bulk metallic glasses

Bulk metallic glasses have a very high corrosion resistance and mechanical strength. Bulk metallic glasses show elastic-perfectly plastic behavior with an extended region of elastic strain (≈ 2%). But at room temperature their macroscopic plasticity is weak even though a local plastic strain is observed in shear bands. A relaxation analysis allowed studying micro-mechanisms of plastic deformation and estimating the apparent activation volume (≈ 2000 ų). __________ Translated from Problemy Prochnosti, No. 1, pp. 167–170, January–February, 2008.     

Characterization of strengthened rapidly quenched Zr-based alloys

The nominal composition components of alloy Zr_66.4Nb_6.4Ni_8.7Cu_10.5Al₈ (Alloy A) were fabricated and characterized. The strengthening of in-situ alloys depends on the role of both the glassy matrix and the second phases. The glass transition and the crystallization kinetics were studied using DSC and X-ray diffraction as a function of element distribution. The amorphous and semi-crystalline structures were identified with the existence of nano crystals in the alloy nominal compositions. The Elastic compression modulus were found to increase with transition to crystallite phase. Where as, the microhardness decreases dramatically with the change from crystalline to amorphous phase. The compression fracture surface shows classic veins behavior. In mode of continuous heating and adiabatic annealing the glass transition, T _g , and the crystalline peak, T _p , temperatures display a strong dependency on heating rate. The activation energy for glass transition and crystallization were determined as E _g  = 226 KJ/mol based on Kissinger method, but during the isothermal process E _g  = 121 KJ/mol.     

Surface alloying of Mg alloys after surface nanocrystallization

Surface nanocrystallization using a surface mechanical attrition treatment effectively activates the surface of magnesium alloys due to the increase in grain boundary diffusion channels. As a result, the temperature of subsequent surface alloying treatment of pure Mg and AZ91 alloy can be reduced from 430 degrees C to 380 degrees C. Thus, it is possible to combine the surface alloying process with the solution treatment for this type of alloy. After surface alloying, the hardness of the alloyed layer is 3 to 4 times higher than that of the substrate and this may significantly improve the wear resistance of magnesium alloys.