DEFORMATION BEHAVIOR AND CONSTITUTIVE EQUATION FOR Zr55Cu30Al10Ni5 BULK METALLIC GLASS IN SUPERCOOLED LIQUID REGION

Zr₅₅Cu₃₀Al₁₀Ni₅块体非晶合金(BMG)在过冷液态区内的单向压缩实验表明: 材料在过冷液态区内的形变行为强烈依赖于温度和变形速率. 随着应变速率的增加, 材料的流变特征由Newtonian流变转变为非Newtonian流变.利用扩展指数本构方程模型建立了非晶合金的流变应力、应变速率和温度的关系.     

Zr55Al10Ni5Cu30块体金属玻璃的摩擦焊焊接

采用摩擦焊对Zr55Al10Ni5Cu30块体金属玻璃进行了焊接,当焊机主轴转速为4.0×103-5.0×103 r/min,摩擦压力为80-100 MPa,摩擦时间为0.2-0.4 s,顶锻压力和保压时间分别为200 MPa和2 s时,能够成功实施Zr55Al10Ni5Cu30金属玻璃的焊接.用SEM,XRD和TEM观察分析未检测到晶化相,焊缝处金属仍保持非晶状态.金属玻璃的塑性在玻璃转变点Tg附近随温度变化很大,在Tg以上具有良好的塑性变形能力,这是实施摩擦焊焊接的重要基础.     

Zr_(55)Cu_(30)Ni_5Al_(10)大块金属玻璃的等时和等温晶化(英文)

采用差示扫描量热仪(DSC)和X射线衍射仪(XRD)研究Zr55Cu30Ni5Al10大块金属玻璃的非等温晶化转变动力学和在过冷液相区的等温晶化动力学行为。在非等温过程中,采用不同方法(Kissinger,Flynn-Wall-Ozawa和Augis-Bennett)得到的Zr55Cu30Ni5Al10大块金属玻璃平均激活能彼此之间吻合很好。此外,采用Johnson-Mehl-Avrami(JMA)模型描述Zr55Cu30Ni5Al10大块金属玻璃的等温转变动力学。研究结果表明:Zr55Cu30Ni5Al10大块金属玻璃的Avrami指数n介于2.2和2.9之间,表明其晶化机制主要是扩散控制过程。在等温晶化的过程中,晶核长大主要是三维的长程有序扩散控制的过程,平均激活能为469kJ/mol。     

SiC颗粒对Zr55Al10Ni5Cu30非晶形成能力和热稳定性的影响

采用铜模铸造方法成功制备了体积分数高达27％的SiC／Zr55All0Ni5Cu30块体非晶复合材料．光学显微镜、X射线衍射和透射电镜分析表明，非晶基体上均匀分布SiC颗粒，SiC颗粒与基体间形成了厚度为10nm的反应层．DSC分析表明，块体非晶复合材料的玻璃转变温度、晶化温度和过冷液相区随SiC体积分数的增加而提高．电子探针分析和计算结果表明，Si原子和部分C原子通过扩散进入基体合金中，从而提高了非晶合金的形成能力和热稳定性．     

添加微量Fe对Zr_(55)Al_(10)Ni_5Cu_(30)块体金属玻璃非晶形成能力和力学性能的影响(英文)

通过磁悬浮熔炼和铜模吸铸法制备直径3mm的(Zr0.55Al0.10Ni0.05Cu0.30)100-xFex(x=0,1,2,3,4)合金试样,研究Fe元素的微量添加对Zr55Al10Ni5Cu30块体金属玻璃非晶形成能力和力学性能的影响。研究表明,合理添加Fe元素(不超过3%,摩尔分数)导致约化玻璃转变温度Trg(=Tg/Tl)和参数γ(=Tx/(Tg+Tl))增大,因而其非晶形成能力增大,但添加过量的Fe元素(4%)会导致其非晶形成能力的降低。添加Fe元素也会显著地改善Zr55Al10Ni5Cu30块体金属玻璃的压缩塑性及提高其压缩断裂强度,当Fe元素的添加量为2%时,直径3mm、长度6mm的试样在压缩时出现一定的塑性及加工硬化现象。Fe元素添加量为4%形成的金属玻璃基复合材料,同样也显示良好的压缩塑性和高的压缩断裂强度。     

Zr41Ti14Cu12.5Ni10Be22.5非晶棒料摩擦焊接

设计了一种非晶合金摩擦焊装置,以Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5非晶棒料为研究对象,进行了摩擦焊试验.焊接样品经SEM,XRD,维氏硬度、TEM等检测,结果显示焊接界面无明显未熔合,样品仍然保持非晶态,接头硬度总体增大,接头处出现了纳米晶.采用ANSYS软件对非晶合金摩擦焊的温度场进行仿真.结果表明,在摩擦时间t=0.25s时摩擦界面中心温度超过非晶棒料玻璃转变温度,接触面全部进入过冷液相区,应进行顶锻.仿真结果与摩擦焊试验结果基本吻合,有利于指导焊接试验.     

Effect of ball-milling and shot-peening on Zr55Al10Ni5Cu30 alloys

Effect of ball-milling and shot-peening on a metallic glass Zr₅₅Al₁₀Ni₅Cu₃₀, which possesses a large supercooled liquid region, has been investigated by means of differential scanning calorimetry, x-ray diffractometry and transmission electron microscopy. Metallic glassy ribbons, powders and plates were prepared by melt-spinning, gas-atomizing and mold-clamp casting techniques, respectively. No structural changes were observed in both the ribbon and powder specimens by ball-milling for around 100 h; however, the powder specimens were crystallized by Fe contamination when they were ball-milled for 540 h. No structural evolution was also observed when the plate specimens were subjected to shot-peening, while crystallized plate specimens were easily amorphized by mild and short period shot-peening. These results imply high phase stability of the Zr₅₅Al₁₀Ni₅Cu₃₀ metallic glass against deformation.     

Zr67.8Cu24.7Al3.43Ni4.07非晶合金激光焊接晶化控制及组织性能分析

对Zr_67.8Cu_24.7Al_3.43Ni_4.07非晶合金进行激光焊接,研究激光功率和焊接速度变化对接头不同区域微观组织的影响,阐述非晶合金激光焊接接头晶化控制的工艺调控规律,并分析接头不同区域的微观结构特征与其硬度之间的关系.结果表明,采用高焊速及高能量密度的激光焊接有利于使Zr_67.8Cu_24.7Al_3.43Ni_4.07非晶合金接头的熔化区保持非晶态结构,同时伴随少量纳米晶产生.热影响区的晶化现象明显,激光功率对接头完全焊透具有较大影响,通过降低激光功率或提高焊接速度以减小热输入,热影响区的晶化程度得到有效控制.焊后接头的熔化区硬度略高于母材,而热影响区的硬度相比于母材显著降低.     

表面粗糙度对Zr52.5Cu17.9Ni14.6Al10Ti5块体非晶合金塑性的影响（英文）

将Zr52.5Cu17.9Ni14.6Al10Ti5（Vit105）块体非晶合金棒用水砂纸和抛光膏打磨到不同粗糙度,研究表面粗糙度对试样压缩变形行为的影响。结果表明,随着试样表面粗糙度的降低,屈服强度并没有明显变化,但压缩塑性从2.3%提高到4.5%。在扫描电镜下观察断裂试样的侧面发现,塑性越大的试样,剪切带的密度越大。因此,对于非晶合金,要得到较大的塑性,降低表面粗糙度是必要的。     

A MICROSCOPIC PHASE–FIELD STUDY FOR THE INFLUENCE OF ORDERING ENERGY ON Cr SUBSTITUTION BEHAVIOR IN Ni75Al15Cr10 ALLOY

通过微观相场方法研究了Ni₇₅Al₁₅Cr₁₀合金在1073 K时效时, 不同原子间有序能下Cr原子的替代行为. 结果表明, 在γ'有序相中, 同时存在Ni--Al原子反位和Cr原子对Ni和Al原子的替代行为, 其中以替代行为为主; 随着第1,3层Ni--Al和Ni--Cr有序能的增大, Cr原子替代Al位的趋势增大, 替代Ni位的趋势减小; 第2, 4层Ni--Al和Ni--Cr有序能增大时, Cr原子替代Ni位的趋势增大, 替代Al位的趋势减小; 第1, 3层Al--Cr有序能增大时, Cr替代Ni位的趋势增大, 替代Al位的趋势减小; 第2, 4层Al--Cr有序能增大时, Cr替代Ni位的趋势减小, 替代Al位的趋势增大.     

Thermal stability of bulk Zr2Al4C5 ceramic at elevated temperatures

Thermal expansion analysis is applied to the study of phase segregation of Zr₂Al₄C₅ at elevated temperatures (20-2000 °C) under flowing argon. Such information would be useful for the detection of phase decomposition temperature and thermal stability of materials. The detected phase-decomposition temperature of Zr₂Al₄C₅ is approximately 1900 °C. The presented thermal expansion analysis results are in good agreement with the X-ray diffraction (XRD) and SEM results. The results indicate that Zr₂Al₄C₅ is susceptible to decomposition through sublimation of high vapor pressure of Al and weaker covalent bonds between ZrC slabs and Al₄C₃ layers. Thus, minimal amounts of Al, Zr₂Al₃C₅, Al₄C₃ and ZrC form on the surface layer. Zr₂Al₃C₅ further decomposes to ZrC_1 − x and Al₄C₃ at 2000 °C. However, the amount of decomposing phase slowly increases, and the structural shape of bulk Zr₂Al₄C₅ ceramic is always kept stable during heat treatment.     

EFFECT OF LaCoO3 COATING ON THE INTERMEDIATE TEMPERATURE OXIDATION BEHAVIOR OF SUS 430 METALLIC INTERCONNECT

通过溶胶--凝胶提拉法在SUS 430合金表面施加LaCoO₃钙钛矿导电涂层, 并研究其对固体氧化物燃料电池(SOFC)金属连接体SUS 430合金中温氧化行为的影响. 利用X射线衍射(XRD)、扫描电子显微镜(SEM)以及能谱仪(EDS)对施加涂层合金的氧化物相结构与微观形貌进行表征, 并采用“4点法”测量施加涂层合金表面氧化膜的面比电阻(ASR).750 ℃空气中的循环氧化结果表明, 施加LaCoO₃涂层合金的氧化动力学曲线遵循抛物线规律,氧化速率常数K为4.18×10^-15 g²/(cm⁴•s),比与未施加涂层合金降低了1---2个数量级;LaCoO₃涂层有效地抑制了Cr₂O₃相的形成, 减缓了MnCr₂O₄尖晶石的生长. 最终使得SUS 430合金的氧化抗力和氧化后的导电性得到增强.     

Evolution of microstructure and non-equilibrium phases in electron beam treated Zr55Cu30Al10Ni5 bulk amorphous alloy

Electron beam (EB) is becoming very popular for the modification of the surfaces as it involves localized melting and fast cooling which helps in achieving the non-equilibrium phases as well as fine microstructure. Surface modification of Zr-based amorphous alloy Zr₅₅Cu₃₀Al₁₀Ni₅ has been carried out by EB melting. Differential scanning calorimetry (DSC) was employed to determine the supercooled liquid region and activation energy of crystallization. The as-cast and modified surfaces of amorphous alloy at different beam conditions were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. Various phases like NiZr₂, CuZr₂ and Cu₁₀Zr₇ were identified which resulted in the enhancement of hardness of the modified alloy surface.     

Thermal stability and crystallisation of a Zr55Cu30Al10Ni5 bulk metallic glass studied by in situ ultrasonic echography

An original in situ ultrasonic echography technique was used to study the thermal stability and crystallisation of a Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass between RT and 630 °C. Changes in Young's modulus with temperature were reported allowing to study the supercooled-liquid state and the crystallisation process. Investigations of viscoelastic properties gave information on the correlation factor (hierarchically correlated motion theory) and three distinct crystallisation stages were observed. Their kinetics were studied using Voigt's and Reuss' approximations for a two-phase material and comparisons with the Johnson–Mehl–Avrami–Kolmogorov theory allowed us to consider a mixed surface/internal nucleation for the first stage and a surface nucleation for the two last stages.     

一种具有优异玻璃形成能力的Zr50Ti5Cu27Ni10Al8大块非晶合金的开发

多组元的Zr基非晶合金成分的复杂性对开发具有优异玻璃形成能力的Zr基非晶合金提出巨大的挑战。另外,大部分Zr基非晶合金含有有毒元素Be或者贵金属。因此,采用一种简单有效的方法开发无毒无贵金属元素的多组元Zr基非晶合金十分必要。本文中采用二元共晶比例法和部分元素替代法快速的开发出了一种新的临界尺寸大于10mm的 Zr50Ti5Cu27Ni10Al8非晶合金。这个非晶合金的热稳定性和硬度也通过原位高温X射线衍射和纳米压痕方法测量得出。     

Microstructure and electrochemical behavior of Ti-coatedZr55Al10Ni5Cu30 bulk metallic glass

In this study, pure Ti was coated on Zr₅₅Al₁₀Ni₅Cu₃₀ bulk metallic glass (BMG) using a physical vapour deposition (PVD) technique with magnetron sputtering. Microstructures of Ti coating, BMG substrate and interface were investigated by conventional and high-resolution transmission electron microscopy (TEM and HREM). The electrochemical behavior of Ti-coated Zr₅₅Al₁₀Ni₅Cu₃₀ BMG was studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in Hanks' solution. Scanning electron microscopy (SEM) was used to characterize the surface morphology of the coating after electrochemical testing. HRTEM observation reveals that the sputtering Ti coating consists of α-Ti nano-scale particles with the size about 10 nm. The polarization curves revealed that the open-circuit potential shifted to a more positive potential and the passive current density was lower after Ti coating was applied in comparison with that of the monolithic Zr₅₅Al₁₀Ni₅Cu₃₀ BMG. Electrochemical impedance spectroscopy (EIS) measurements showed that the Bode plots of Ti-coated Zr₅₅Al₁₀Ni₅Cu₃₀ BMG presented one time constant for 1 h and 12 h immersion and two time constants after 24 h immersion. The good bonding condition between Ti coating and Zr₅₅Al₁₀Ni₅Cu₃₀ BMG substrate may be responsible for the high corrosion resistance of Ti-coated Zr₅₅Al₁₀Ni₅Cu₃₀ BMG.     

Zr_(55)Al_(10)Ni_5Cu_(30)大块非晶合金在过冷液相区内虚拟应力模型的改进

针对描述非晶合金在过冷液相区流动行为的虚拟应力模型虽然能定性分析应力-应变关系,但定量计算误差很大的问题,以Zr55Al10Ni5Cu30为例,采用MATLAB遗传算法优化弹性模量、最大应力和最大松弛时间,提高了模型对应力峰值及稳态应力值的计算精度;提出时间调整因子概念,可提高对应力变化历史描述的准确度;改进后的虚拟应力模型与Zr55Al10Ni5Cu30大块非晶合金单轴压缩实验的结果吻合较好。     

ELECTROMECHANICAL COUPLING COEFFICIENT (K33) OF Fe72.5Ga27.5 MAGNETOSTRICTIVE ALLOY

采用区熔定向凝固法制备目标成分为Fe_72.5Ga_27.5的磁致伸缩定向生长试样. 采用改进的交流阻抗法测定定向生长态及其淬火态(1000 ℃/3 h, W. Q.)试样的阻抗谐振频率谱, 求出不同偏振磁场和预压力情况下的动态机电耦合系数K₃₃. 由于Fe--Ga合金的磁致伸缩性能比Tb--Dy--Fe巨磁致伸缩材料小一个数量级, 原有的测试方法不易得到Fe--Ga合金的K₃₃. 本实验在拾取信号时采用了四线并接接线方式并将交流激励信号输入水平调整到0.5 A, 获得了稳定且明显的Fe--Ga合金阻抗谐振频率谱线. 实验结果表明: 定向生长试样在32.7 mT偏振磁场、无预压应力下K₃₃为0.103; 淬火态试样在同样偏振磁场和无预压应力下
K₃₃达到0.137. K₃₃随外加偏振磁场的增大而减小, 随预压力的增大呈现先增大而后减小的趋势. 淬火态试样的K₃₃较定向生长试样有明显提高. 外加偏振磁场和预压力对淬火态试样的K₃₃的影响规律同定向生长试样一致.     

阳极氧化法制备TiO2膜在模拟深海热液区的耐腐蚀性能

以恒压阳极氧化方法在钛基体上制备TiO₂氧化膜,使用水热釜模拟深海热液区的条件研究其耐腐蚀性能。采用XRD、SEM、接触角测定仪对氧化膜以及腐蚀试样产物进行晶型、表面结构、化学成分和亲疏水性能测定,使用动电位扫描方法对其进行极化曲线测试。结果表明,钛试样和阳极氧化钛试样在模拟深海环境条件下,经过腐蚀反应在表面都生成了一层非致密的TiO₂ 膜,对基体并不能起到保护作用,而阳极氧化生成的致密TiO₂ 膜对基体能够起到很好的保护作用。经腐蚀后钛试样表面有TiH₂相的形成,腐蚀电位负移0.45 V。而阳极氧化钛试样表面没有TiH₂相的形成,且腐蚀电位负移较小,表现出良好的耐腐蚀性能。     

Zr55Al10Ni5Cu30块状非晶合金的高温压缩断裂

利用Gleeble1500热模拟试验机研究了Zr55Al10Ni5Cu30块状非晶合金的高温压缩断裂，在室温情况下，在块状非晶合金断面的脉纹壁上出现了带有锯齿形边缘的裂口，在高温情况下，Zr55Al10Ni5Cu30块状非晶合金的宏观断面变得粗糙不平并出现了台阶，随着实验温度的不断上升，断面粘性流动特性变得更加明显，断面出现了大面积类似流动熔体凝固后的特征结构，塑性形变产生的最大剪切面的绝热温升或熔比是块状非晶合金中部粘性流动的原因。