Preparation and Mechanical Properties of Misch Metal Based Bulk Metallic Glasses

Bulk metallic glasses(BMGs)have been devel-oped in many alloy systems during past decade.Among these systems,rare-earth(RE)metal-basedBMGs are ones of those found earliest and with betterglass forming ability(GFA).For example,La-basedBMGs were the first a…     

Kinetics of Glass Transition and Crystallization in Carbon Nanotube Reinforced Mg-Cu-Gd Bulk Metallic Glass

Mg65Cu25Gd10 bulk metallic glass and its carbon nanotube reinforced composite were prepared. Differential scanning calorimeter （DSC） was used to investigate the kinetics of glass transition and crystallization processes. The influence of CNTs addition to the glass matrix on the glass transition and crystallization kinetics was studied. It is shown that the kinetic effect on glass transition and crystallization are preserved for both the monothetic glass and its glass composite. Adding CNTs in to the glass matrix reduces the influence of the heating rate on the crystallization process. In addition, the CNTs increase the energetic barrier for the glass transition. This results in the decrease of GFA. The mechanism of the GFA decrease was also discussed.     

Crystallization of a Ti-based Bulk Metallic Glass Induced by Electropulsing Treatment

The effect of electropulsing treatment (EPT)on the microstructure of a Ti-based bulk metallic glass (BMG)has been studied.The maximum current density applied during EPT can exert a crucial role on tuning the microstructure of the BMG.When the maximum current density is no more than 2 720 A/mm2 ,the samples retains amorphous nature,whereas,beyond that,crystalline phases precipitate from the glassy matrix.During EPT,the maximum temperature within the samples EPTed at the maximum current densities larger than 2 720 A/mm2 is higher than the crystallization temperature of the BMG,leading to the crystallization event.     

Self-organized Criticality Behavior in Bulk Metallic Glasses

Serrated flows are known as repeated yielding of bulk metallic glasses (BMGs)during plastic deformation under different loading conditions,which are associated with the operation of shear banding.According to the statis-tics of some parameters,the shear avalanches can display a self-organized critical state,suggesting a large ductility of BMGs.The emergence of the self-organized criticality (SOC)behavior in different BMGs is due to the tempera-ture,strain rate,and chemical compositions.The SOC behavior is accompanied with the following phenomena:the interactions occur in the shear bands;the incubation time is longer than the relaxation time;the time interval is lac-king of typical time scale;and the spatial or temporal parameters should display a power-law distribution.     

块体Pd77.5Cu6Si16.5非晶合金的晶化动力学研究

应用变温条件下的JMA方程和Kissinger方程研究长体Pd77.5Cu6Si16.5非晶合金的晶化动力学行为。计算了其玻璃转变温度Tg，晶化起始温度Tx，晶化峰值温度Tpl的激活能E，频率因子和Avrami指数等晶化动力学参数。并将这些参数与非晶条带的相应参数做对比，发现一些描述晶化过程的参量发生了变化。实验结果表明，块体非晶合金的原子活动性小于传统非晶条带，而具有更宽的过冷液相区。     

Zr41Ti14Cu12.5Ni10Be22.5块状非晶合金的相变动力学

用差式扫描热分析和X射线衍射方法，研究了Zr41Ti14Cu12.5Ni10Be22.5块状非晶合金的相变动力学。结果表明：在温度低于500℃的范围内，Zr41Ti14Cu12.5Ni10Be22.5块状非晶合金中的晶化相可大体分为α相和β相（主要为Ti2Ni和Zr2Cu等）。在晶化初期α相的激活能较小，为159kJ/mol,它随着晶化分数X的增加而提高，在X为90％时达到最大值220kJ/mol；β相的晶化激活能在X为5％－60％的范围内变化不大，然后随晶化分数X的增加而提高，X为65％时达到最大值257．35kJ/mol。     

块体金属玻璃的研究现状

介绍了块体金属玻璃的研究和进展。阐述了常见的制备块体金属玻璃的主要方法，如熔体水淬法、铜模吸铸法、熔体喷铸与真空吸铸相结合的制备技术、压铸法、定向凝固铸造法、磁悬浮熔炼铜模冷却法、以金属玻璃为基复合材料的制备方法以及金属玻璃合金丝和管的制备，简要说明了块体金属玻璃的性能特征及应用，并提出了研究过程中值得重视的三个问题。     

Ti对部分晶化Ni基非晶合金电化学腐蚀性能的影响

采用水冷铜模吸铸法制备出部分晶化的Ni55Nb30Sn5Ti5Zr5和Ni55Nb30Sn5Zr10块体非晶合金,并利用X射线衍射（XRD）分析和示差扫描量热仪分析（DSC）对合金的相组成及热物性参数进行了测量分析。采用极化曲线法研究合金在不同溶液中的腐蚀行为,并利用失重法测定合金在10%HCl溶液中的腐蚀速率,对腐蚀后的显微形貌及表面成分进行了扫描电镜（SEM）观察和能谱分析（EDS）。结果表明,Ni55Nb30Sn5Ti5Zr5合金比Ni55Nb30Sn5Zr10合金具有更宽的过冷液相区和更好的抗腐蚀性能。随着合金晶化相的增多,合金抗腐蚀性能降低。Ti元素的加入可在合金表面形成氧化钛的保护膜,从而使合金的抗腐蚀性能提高。     

Co68.5Fe4Si10B17.5非晶合金晶化动力学行为研究

采用示差热分析(DSC)研究了旋铸急冷法在大气环境中制备出的Co68.5Fe4Si10B17.5非晶合金的非等温晶化的动力学行为。研究发现:在连续加热条件下,随升温速率的加快,合金的特征温度Tg,Tx,Tp均向高温区移动。当分别采用晶化开始温度和峰值温度时,所得非晶合金的激活能并不是稳定值。用Doyle-Ozawa方法计算出的激活能值比Kissinger法计算出的激活能值要大。非晶态Co68.5Fe4Si10B17.5合金的晶化百分比与退火温度和退火时间的关系曲线均呈S型。随加热速度的增加,非晶合金的晶化百分比与温度的关系曲线向高温处移动。     

Rate Dependence of Serrated Flow and Its Effect on Shear Stability of Bulk Metallic Glasses

The rate dependence of serrated flow and its effects on the stability of shear banding were systematically investigated in a prototypic bulk metallic glass.It was found that with the increase of external strain rate,the serra-ted flow is gradually suppressed and could completely disappear at a critical strain rate.The serration size,character-ized by the mean stress drop amplitude,decreases inversely with the strain rate,while the waiting time for serration decreases with the strain rate in a power-law manner.The rate dependence of the serrated flow has important effects on the dynamics and stability of shear banding process,and leads to an optimal plasticity achieved around the critical strain rate for the disappearance of serrated flow.These results are discussed and interpreted in terms of the mi-croscopic deformation theory and the stick-slip dynamics of shear banding for bulk metallic glasses.     

Crystallization mechanism of CeAlFeCo bulk metallic glasses

Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of different samples were simulated by JMA equation.Experimental results demonstrated that incubation and crystallization time increased with decreasing isothermal temperature for the same sample.The crystallization mechanism of CeAlFeCo BMGs was discussed.     

Thermodynamic and Kinetic Study of Crystallization Reaction of Fe/Dy Multilayers Form Amorphous State

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Preparation and Thermal Stability of Phosphate System Protection Glasses Doped with Rare Earths

The formation ability and thermal stability of phosphate laser protection glass doped with high Sm2O3 content were discussed. The characteristic temperatures (Tg, Tc, Tm) were measured by DSC and the crystallization parameter β was calculated. The results show that the forming regions would shrink and tend to closed ellipse with increasing of Sm2O3 content. Increasing of BaO/Al2O3 ratio changes the network structure of rare earth glass and improves the thermal stability finally. However, with the increasing of Sm2O3 content, the β increases firstly and then decreases, and finally the thermal stability also increases firstly and then decreases.     

Ti基大块金属玻璃的研究与应用

阐述了Ti基大块金属玻璃(BMG)的成分设计原则及制备方法，并对Ti基非晶合金及其部分晶化复合材料的力学性能及断裂机理进行了评述。结果表明：Ti基大块金属玻璃具有较高的断裂强度、弹性延伸率及一定的塑性延伸率，而经过部分晶化获得的非晶合金基纳米颗粒复合材料，其室温塑性获得很大的改善。在此基础上探讨了该合金目前所存在的问题、研究热点以及其应用前景。     

Corrosion Behavior of Fe-based Bulk Metallic Glass and In-situ Dendrite-reinforced Metallic Glass Matrix Composites in Acid Solution

The corrosion behavior study was conducted on a novel Fe_(77)Mo_5P_9C_(7.5)B_(1.5)in-situ metallic glass matrix composite(MGMC).This composite sample was developed by introduction of bccα-Fe dendrites as reinforcing phase.The corrosion behavior of this composite was compared to its monolithic counterpart and other Fe-based alloys such as 304 Land 2304Lstainless steels.The corrosion resistance of MGMCs in H_2SO_4 solution shows inferior to that of other Fe-based alloys.Experiments suggest that Fe-BMGs samples possess better corrosion resistance property than that of Fe-MGMCs.The possible underlying reasons can be the inhomogeneity induced by the precipitation ofα-Fe dendrites in the MGMCs.     

铒硼硅酸盐玻璃结构的研究

通过对Er2O3-Al2O3-B2O3-SiO2玻璃红外光谱和激光拉曼光谱的分析表明,该系统玻璃中存在[SiO4][、BO3][、BO4][、AlO4][、AlO6]等基团。同时对玻璃进行析晶热处理,热处理后析晶产物为ErBO3相,表明稀土玻璃中的Er3+主要偏聚在富硼相中,在受热过程中发生了分相,并以ErBO3相的形式析出,富硅相则保持玻璃态。将稀土玻璃结构与析晶产物联系起来研究,在一定程度上可以揭示稀土玻璃的结构形式,根据研究结果提出了Er2O3-Al2O3-B2O3-SiO2玻璃的结构模型。     

Study on Thermal Stability and Spectroscopic Properties of Nd3+ -Doped Phosphate Laser Glasses

Fluorescence spectra, absorption spectra and thermal stability properties of Nd3 -doped phosphate laser glasses were tested in this work. We calculated spectroscopic parameters of Nd3 -doped phosphate laser glasses according to their absorption spectrum. Measuring and calculating linear thermal expansion coefficient, and analysising thermal stability of glasses show that this kind of Nd3 -doped phosphate laser glasses has thermal expansion coefficient α = 38.75× 10 -7/℃ and optimal spectroscopic properties which extend application range of Nd 3-doped phosphate laser glasses.     

Effect of Samarium on Mn Activated Zinc Borosilicate Storage Glasses

Electron-trapping materials (ETMs) are such kindof materials that can store the energy of incident lightrangingfromenergetic radiation to visible light that canbe releasedfromthetraps bythethermal or optical stim-ulationinthe formof thermoluminescence (TL) or opti-cally/photo stimulated luminescence (OSL/PSL) .ETMsare widely usedinthe filed of detectingradiation,infor-mation storage ,radiology,space exploring,indicator inthe dark and craft ,etc[1 ~6].In ETMs ,in additiontothe activation …     

Thermodynamics and Magnetostriction of Fe-Co-B-Si-Nb-C Bulk Metallic Glasses

Fe-Co-B-Si-Nb-C glassy alloy with the addition of C was prepared by arc melting and copper suck-casting. The thermodynamics and soft magnetic properties were investigated. The casted amorphous alloys were heat-treated at different temperatures. The differential scanning calorimeter (DSC) results and thermal expansion show complete thermodynamics of crystallization. Its magnetostriction properties were studied by capacitance method. Saturation magnetostriction increases to 38×10-6. The amorphous alloy exhibits good soft magnetic properties with low coercivity and high saturation magnetic induction. The results show that minor addition of C is beneficial to enhance the saturation magnetostriction λs, and do not deteriorate the ability of forming amorphous.     

Thermal Decomposition Reaction Kinetics Model of Powdered Bastnaesite

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