Formation and Mechanical Properties of Zr-Nb-Cu-Ni-Al-Lu Bulk Glassy Alloys with Superior Glass-Forming Ability

Glass-forming ability(GFA) and mechanical properties of(Zr_(0.58)Nb_(0.03)Cu_(0.16)Ni_(0.13)Al_(0.10))_(100-x)Lu_x(x= 0-3 at%) alloys have been investigated.The GFA of Zr_(58)Nb_3Cu_(16)Ni_(13)Al_(10) alloy is dramatically enhanced by adding Lu.The(Zr_(0.58)Nb_(0.03)Cu_(0.16)Ni_(0.13)Al_(0.10))_(98)Lu_2 alloy possesses the highest GFA in the studied Zr-Nb-Cu-Ni-Al-Lu alloys,with its critical diameter for glass formation reaching 20 mm by copper-mould casting method,while that of the Lu-free Zr_(58)Nb_3Cu_(16)Ni_(13)Al_(10) alloy is 7 mm.The critical diameters of(Zr_(0.58)Nb_(0.03)Cu_(0.16)Ni_(0.13)Al_(0.10))_(100-x)Lu_x(x =1 at%and 3 at%) alloys are 15 mm and 12 mm,respectively.The Lu addition to Zr_(58)Nb_3Cu_(16)Ni_(13)Al_(10) alloy induces the change of initial crystallization phases from face-centred-cubic Zr_2Ni and tetragonal Zr_2Ni phases for the Lu-free Zr_(58)Nb_3Cu_(16)Ni_(13)Al_(10) alloy to an icosahedral quasi-crystalline phase for the Lu-doped alloys,which may be the origin for the enhanced GFA of the Lu-doped alloys.The compressive fracture strength and plastic strain of the bulk glassy(Zr_(0.58)Nb_(0.03)Cu_(0.16)Ni_(0.13)Al_(0.10))_(98)Lu_2 alloy are1 610 MPa and 1.5%,respectively.     

Effect of Friction Stir Welding on Bulk Metallic Glasses

In order to enlarge the size of bulk metallic glasses (BMGs),two Cu_(36)Zr_(48)Al_8Ag_8 BMGs plates were successfully welded by friction stir welding (FSW) without obvious crystallization.The effect of friction stir welding on microstructure and mechanical properties of the BMGs was investigated.X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to evaluate the changes of the crystalline particles in the BMGs.Nanoindentation was applied to analyze the changes of the amorphous matrix.Micro-hardness of the stir zone before and after FSW was tested to explore changes of the mechanical properties.Results show that the original Al_3Zr particles in the BMGs were refined and some cavities parallel to the rotating direction of the pin were observed in the amorphous matrix after FSW.Furthermore,micro-hardness of the stirred zone rises approximately 50 Hv compared with the as-cast sample due to structure relaxation of the amorphous matrix.     

Zr63Al10Ni10Cu14Nb3大块非晶合金的力学行为研究

通过电弧熔炼并利用吸铸的方法制备了长70 mm、直径3 mm的Zr63Al10Ni10Cu14Nb3大块非晶合金.热稳定性分析表明:该合金具有较大的过冷液相区.室温压缩实验显示合金具有很高的屈服强度,在合金发生屈服之后应力-应变曲线上有明显的锯齿现象和一个明显的应变软化阶段.结合断口形貌特征,分析并讨论了非晶合金的剪切断裂机理.     

Vogel—Fulcher定律与玻璃转变温度的关系

文章通过测定Ｉｎ、Ｚｎ、Ｓｎ、ｐｂ等元素随加热速度变化在不同坩埚和不同重量条件下其熔点变化的规律,校正了加热速度对差示扫描量热仪显示的影响。根据对仪器温度校正的结果,测量了Ｎｉ３３Ｚｒ６７、Ｚｒ６５Ａｌ７．５Ｎｉ１０Ｃｕ１５Ｃｏ２．５、Ｐｔ６９．０Ｎｉ９．６Ｐ２１．４、聚醚砜（ＰＥＳ）和聚苯乙烯（ＰＳ）等材料的玻璃转变的动力学特征。结果表明玻璃转变温度的增加与加热速度对数的增加成正比,而这种关系并     

体积分数40％的W丝增强Zr41．25Ti13．75NiloCu12．5Be22．5块状非晶复合材料的变形行为

室温下对体积分数为40％的W丝增强Zr41．25Ti13.75Ni10Cu12.5Be22.5块状非晶基复合材料的室温单轴压缩断裂行为进行了研究。结果表明，该非晶复合材料的室温准静态下的压缩变形过程主要表现为弹性和塑性变形，并且塑性变形阶段无明显加工硬化现象产生，断裂方式为纵向劈裂。塑性变形中，非晶基体以剪切带粘性流层相对滑动的方式进行；而W丝则表现为韧性化的撕裂行为。正应力在剪切带的形成与发展过程中起黄重要作用。     

Strain rate response of a Zr-based composite fabricated by Bridgman solidification

Zr_(58.5)Ti_(14.3)Nb_(5.2)Cu_(6.1)Ni_(4.9)Be_(11.0) bulk metallic glass matrix composites,containingβ-Zr dendrites,were fabricated by Bridgman solidification at the withdrawal velocity of 1.0 mm/s through a temperature gradient of～45 K/mm.Subjected to the increasing compressive strain rates,the monotonic increasing and decreasing were obtained for the maximum strength and the fracture strain,respectively.The results show that high strain rate may induce the insufficient time for the interaction between s...     

Cu—Zr—Al大块非晶合金的制备及性能研究

采用铜模铸造的方法制备了Cu48Zr52-x Alx（x=6,7,8,9,10,at％）几种合金奠射线衍射（XRD）实验检验Cu48Zr44Al8,Cu48Zr43Al两种合金样品为完全非晶态．对样品进行差示扫描量热分析（DSC）考查三种大块非晶合金的非晶形成能力,以及灿的添加对非晶形成能力的影响．结果表明：当铝含量X=9时,合金的非晶形成能力及热稳定性最好．     

Low-frequency Internal Friction Behaviour of Zr_(55)Al_(10)Ni_5Cu_(30) Metallic Glass with Different Quenching Temperatures

The correlation between the internal friction behaviour of Zr_(55) Al_(10) Ni_5 Cu_(30) BMG samples and their quenching temperatures was investigated. It was found that, below the glass transition temperature, the activation energy decreased with increasing quenching temperature, but in the surpercooled liquid region the activation energy tended to be enhanced with a further increase in the quenching temperature. Besides, there were both anelastic and viscoelastic relaxation for the amorphous alloys. The anelastic behaviour would change into viscoelastic relaxation easily for the samples prepared at higher temperature.     

Preparation and mechanical behavior of Mg-based bulk metallic glasses and their matrix composite

Mg87-xCuxDy13(x=22,27,32) bulk metallic glasses (BGMs) with a diameter of 6-8 mm and in-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite with a diameter of 3 mm have been prepared by copper mould casting. The glass forming ability (GFA) of Mg-Cu-Dy alloys have been investigated by differential scanning calorimetry (DSC) and X-Ray diffraction (XRD) and tne mechanical properties have been measured. Results show that Mg87-xCuxDy13(x=22,27,32) alloys in the Mg-Cu-Dy alloy system exhibit excellent GFA, and Mg60Cu27Dy13 alloy has the largest GFA among these alloys. And In-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite exhibits some work hardening and a high fracture compressive strength of 702.38 MPa and some plastic strain of 0.81%. The improvement of the mechanical properties is attributed to the fact that the Mg phase distributed in the amorphous matrix of the alloy has some effective load bearing and plastic deformation ability to restrict the expanding of shear bands and cracks and produce its own plastic deformation.     

Atomistic simulation study of favored compositions of Ni-Nb-Al metallic glasses

This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The simulations not only showed the physical origins of the amorphous phase formation, but also quantitatively predicted a hexagonal compositional region that energetically favors the glass formation. The energy difference between the solid solution and metallic glass, which generates the amorphization driving force (ADF), was suggested to indicate the glass-formation ability (GFA) of each alloy. Based on the computed ADFs, the Ni₅₅Nb₂₅Al₂₀ alloy exhibited the highest GFA among the Ni-Nb-Al members, implying that the glass formed by this amorphous alloy is more thermodynamically stable than other alloys in the system. In a Voronoi tessellation analysis, the knee point of the coordination-number distribution curve corresponded to the glass-formation region of the Ni-Nb-Al system.     

锆基非晶合金在NaOH溶液中的腐蚀行为

用电化学极化曲线研究锆基非晶合金Zr53.5Cu26.5Ni5Al12Ag3在25℃和60℃温度下,在0.01 mol/L和0.1 mol/L的NaOH溶液中腐蚀100 h的腐蚀行为,并用金相显微镜和扫描电镜对腐蚀前后试样的表面形貌进行观察与分析.极化曲线的测试结果表明：锆基非晶合金在25℃下,在浓度为0.01 mol/L和0.1 mol/L的NaOH溶液中浸泡100 h,随着NaOH溶液浓度的升高,非晶合金的耐腐蚀能力下降;锆基非晶合金在25℃和60℃下,在浓度为0.01 mol/L的NaOH溶液中浸泡100 h,随着NaOH溶液温度的升高,非晶合金的耐腐蚀能力下降;锆基非晶合金和晶态合金在60℃下,在浓度为0.1 mol/L的NaOH溶液中浸泡100 h,非晶合金的耐腐蚀性能优于晶态合金.最后根据电化学腐蚀原理,从腐蚀介质温度和浓度方面的性质探讨锆基合金耐蚀性能的因素.     

Enhanced Corrosion and Wear Resistances of Zr-based Alloy Induced by Amorphous/Nanocrystalline Coating

To improve corrosion and wear resistances of the Zirconium(Zr) based alloys which are widely applied in nuclear reactors and chemical corrosion-resistant equipment, a new surface modification scheme was designed to deposit a Zr_(75)Cu_(25) coating on Zr substrate by using magnetron sputtering technique. The microstructure and the phase composition were characterized by scanning electron microscope, transmission electron microscope, and X-ray diffraction measurements. The tribological properties and the corrosion resistance were investigated by performing reciprocating tribo-tester and electrochemical tests, respectively.It is found that the Zr_(75)Cu_(25) coating is made up of a mixture of amorphous and a-(Zr) nanocrystalline phases.The nanocrystalline particles with a size of 5-10 nm are homogenously dispersed in the amorphous matrix.The Zr_(75)Cu_(25) coating shows excellent tribological properties, due to the dispersion strengthen caused by the homogeneous distribution of a-(Zr) nano-size particles among the amorphous matrix. In addition, it is revealed that the Zr_(75)Cu_(25) coating makes the Zr substrate exhibit excellent corrosion resistance, due to the robust passive film with a compact structure of the amorphous/nanocrystalline mixture.     

Bulk glass formation in ternary Cu-Zr-Ti system

The formation of bulk metallic glasses (BMGs) in ternary Cu-Zr-Ti system was investigated by a copper mold casting method. The nature of the amorphous phase was verified by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was demonstrated that the BMGs could be formed in a broad composition range in this system. Cu50Zr42.5Ti7.5, Cu60Zr27.5Ti12.5, Cu60Zr30Ti10 and Cu60Zr32.5Ti7.5 alloys exhibit strong glass-forming ability (GFA), and fully glassy rods of 5 mm in diameter can be obtained. In the center region of the ternary diagram, however, the GFA of the alloys was degraded due to the presence of Laves phase. The degradation of the GFA results from easy nucleation of the Laves phase in the undercooled liquid.     

Chemical short-range order domain in bulk amorphous alloy and the prediction of glass forming ability

Since the discovery of bulk Zr-Ti-Cu-Ni-Be[1] and Pd-Ni-Cu-P[2] metallic glasses with ex-traordinary high glass forming (GFA) ability and critical cooling rate lower than 100 K/s, great attention has been paid to the structure of BMG alloys. Experimental results of X-ray and neutron diffraction or scattering have provided ample evidence that there is a short-range order in BMG alloys. Metallic glasses always exhibit strong compound forming tendency and the corresponding anomalies of t…     

Effects of yttrium on the formation and magnetic properties of bulk metallic glassy （Fe, Co）-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) and [(FexCo1-x)0.72B0.192Si0.04]Nb0.04]96Y4 (x=0.5-0.8) were prepared by copper mold casting. The structure, thermal stability,and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding lat% to 6at% of yt-trium, the bulk glassy alloy rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe1-xCox)B0.192Si0.048Nb0.04]96Y4 (x=0.5-0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (Ms) increased.     

Nd_(60)Al_(10)Ni_(10)Cu_(20)大块金属非晶的玻璃转变和晶化特性研究

用铜模吸铸法制得了一种直径为5 mm、成分为Nd60Al10Ni10Cu20的大块非晶合金.与富Fe类Nd基非晶不同的是,这种新型的Nd基大块非晶具有明显的玻璃转变过程和稳定的过冷液相区.磁性测试表明,在室温下表现为顺磁性.热分析实验发现,随着升温速率的增大,样品的过冷液相区变宽,并且玻璃转变温度和晶化温度有明显的向高温方向移动的趋势.研究了该大块非晶的玻璃转变动力学和晶化动力学,并给出了Kauzmann温度Tk,Vogel-Fulchers-Tamman温度T0g以及脆性系数m等重要参数.     

Y对Cu基非晶合金的玻璃形成能力和力学性能的影响

研究了添加微量稀土元素Y对Cu基非晶合金的玻璃形成能力和力学性能的影响.通过铜模吸铸法制备Cu-Zr-Al-Y大块非晶合金,利用DSC和XRD分析合金的玻璃形成能力对合金进行室温压缩性能测试,用SEM分析了微观断口形貌.研究结果表明:适量Y掺入可提高合金的玻璃形成能力,当Y元素掺入量为3%时,Cu47Zr42Al8Y3非晶合金的过冷液相区宽度ΔT达到72.42K,有较高的玻璃形成能力;Y元素的掺入有利于提高合金的力学性能,而Cu47Zr42Al8Y1合金有最佳的力学性能,其压缩断裂强度为2 140.8 MPa,伸长率达到7.17%,且随着Y含量的增加,断裂方式由单一的剪切断裂变为剪切断裂和脆性断裂复合方式.     

Critical serrated flow features during nanoindentation in La-based bulk metallic glasses

La57.6Al17.5(Cu,Ni)24.9 and La64Al14(Cu,Ni)22 bulk metallic glasses (BMGs) were prepared by copper-mould casting method. Plastic deformation behavior of the two BMGs at various loading rates was studied by nanoindentation. The results showed that the La57.6Al17.5(Cu,Ni)24.9 BMG with a glass transition temperature of 423 K exhibited prominent serrated flow at low loading rates, whereas less pronounced serrated flow at high rates during nanoindentation. In contrast, the La64Al14(Cu,Ni)22 BMG with a glass transition temperature of 401 K exhibited prominent serrated flow at high loading rates. The different rate dependency of serrated flow in the two La-based BMGs is related to the different glass transition temperature, and consequently the degree of viscous flow during indentation at room temperature. A smoother flow occurs in the alloy with relatively lower glass transition temperature, due to the relaxation of stress concentration.     

Influence of flux treatment on the glass forming ability of Pd-Si binary alloys

Pd81Si19 amorphous alloys were prepared by combination methods of melt spinning and B2O3 flux treatment. A compari- son between the ribbons prepared from the fluxed ingots and the non-fluxed ones has been carried out. The result reveals that after fluxing treatment the glass transition temperature of the as-prepared glassy ribbons is reduced while the initial crystallization tem- perature is enhanced. It results in that the supercooled liquid region (defined as the difference between the initial crystallization tem- perature and the glass transition temperature) of the glassy alloy treated with fluxing technology has been increased from 31 to 42 K. This shows that fluxing technique can enhance the glass forming ability (GFA) of the binary alloy and improve the thermal stability of supercooled liquid of the glassy alloy.     

非晶合金摩擦焊装置设计

为了增大非晶合金尺寸,设计了一种新型摩擦焊装置,用来连接毫米尺度的非晶合金棒料.该装置主要由主轴旋转单元,直线驱动单元以及参数控制单元三部分组成,分别实现工件的旋转、直线运动、摩擦焊接参数控制及采集.采用LABVIEW软件搭建了操作界面,实现焊接过程中主要参数的输入及监控采集.以Zr 55Cu 30Al 10Ni5非晶棒料为焊接对象,在不同焊接参数下进行了摩擦焊试验.结果表明,较高的转速能更快的让摩擦界面较短时间内完全进入过冷液相区,成功实现工件连接.新型摩擦焊装置能够实现非晶合金棒料的连接,达到设计要求.