Zr55Al10Ni5Cu30非晶合金晶化相转变的价电子结构分析

基于EET理论,计算了F-Zr₂(Ni,Cu)和tI-Zr₂Cu及tI-Zr₂(Cu,Ni)相的价电子结构,用最强键键合力n₁、结构单元总成键能力F和单位成键能力F_v分析了F-Zr₂Ni亚稳相向tI-Zr₂Cu型稳定相的转变过程。研究发现:F-Zr₂Ni的n^{F-Zr₂Ni₁值比tI-Zr₂Cu的ntI-Zr₂Cu₁值大115.36%,FF-Zr₂Ni_v值比tI-Zr₂Cu的FtI-Zr₂Cu_v值大34.03%;F-Zr₂(Ni0.3,Cu0.7)的nF-Zr₂(Ni0.3,Cu0.7)₁值比tI-Zr₂Cu的ntI-Zr₂Cu₁值大0.36%,FF-Zr₂(Ni0.3,Cu0.7)_v值比tI-Zr₂Cu的FF-Zr₂Ni}_v值大1.25%; tI-Zr₂(Cu0.6,Ni0.4)的n^{tI-Zr₂(Cu0.6,Ni0.4)₁值比F-Zr₂(Ni0.3,Cu0.7)的nF-Zr₂(Ni0.3,Cu0.7)}₁值大12.95%, F^{tI-Zr₂(Cu0.6,Ni0.4)_v值比F-Zr₂(Ni0.3,Cu0.7)的FF-Zr₂(Ni0.3,Cu0.7)}_v值大14.41%; 从价电子结构角度看,F-Zr₂Ni不能直接转变为tI-Zr₂Cu,F-Zr₂(Ni,Cu)不易分解重构为tI-Zr₂Cu;F-Zr₂(Ni0.3,Cu0.7)可分解并转变为tI-Zr₂(Cu0.6,Ni0.4)。     

Zr46Cu46Al7Gd1块体非晶合金氧化过程的光学表征

相比于晶态合金,非晶合金表现出显著不同的氧化行为,其氧化过程受无序原子结构和非平衡状态的影响.为揭示非晶合金的早期氧化过程,需要对其氧化行为进行快速表征.本文以Zr₄₆Cu₄₆Al₇Gd₁块体非晶合金为对象,通过测量光学常数的变化对氧化行为进行表征.与X射线衍射、扫描电子显微镜和热重分析测得的结果相比,光学常数不仅可以反映非晶合金发生明显氧化的起始温度,还可以反映难以用传统方法表征的早期氧化过程.本研究结果说明光学常数是反映氧化行为的灵敏参数,将有助于认识非晶合金氧化过程随温度、时间和组分变化的演化过程.     

基于Zr55Cu30Al10Ni5的块体金属玻璃成分优化设计及其晶化行为

参照Zr₅₅Cu₃₀Al₁₀Ni₅合金的成分并应用团簇加连接原子模型,设计具有高玻璃形成能力的Zr-Cu-Al-Ni体系成分。在Zr-Cu-Al-Ni四元体系中,先定出两个与金属玻璃形成相关的晶化相CuZr₂和CuZr,其中的局域结构可分别用团簇表述为[Cu-Zr₈Cu₄]和[Cu-Zr₈Cu₆],然后应用双团簇模型将这两个团簇按照1∶1的配比构建双团簇式,连接原子个数为2或4或6,由此确定总原子个数为30或32或34,进而选择双团簇式原子总数为32设计出最接近Zr₅₅Cu₃₀Al₁₀Ni₅合金的四元块体金属玻璃成分Zr₁₇Cu₁₀Al₃Ni₂≈Zr_53.1Cu_31.3Al<...     

粉末冶金制备大块非晶合金研究进展

粉末冶金作为制备大块非晶合金的主要方法之一,与快速冷凝相比,该方法可以在更广的合金系、更宽的成分范围内制备出尺寸更大、形状复杂、近净成形的大块非晶合金材料,因此粉末冶金是一种极具前景的大块非晶合金的制备方法.简要介绍了粉末冶金制备大块非晶合金的基本过程,详细阐述了各种成形技术的特点、原理、优缺点以及制备大块非晶合金的研究进展,期望为非晶、纳米晶粉末的致密化研究和制备大块非晶合金提供技术指导.     

低温弛豫对Mge5 Cu25 Gd10大块非晶合金热稳定性及力学行为影响

Mg65 Cu25 Gd10非晶合金的热稳定性关系到其作为结构材料的实用性及发展前景。利用差示扫描量热法（DSC）研究了预先低温弛豫处理后Mg65 Cu25 Gd10非晶的特征转变温度和晶化激活能，分析了低温弛豫对其热稳定性的影响，通过Kissinger方程计算其晶化激活能、频率因子、反应速率系数进一步说明此非晶的晶化过程。同时，通过比较其力学性能的变化，发现非晶压缩性能受非晶稳定性影响不大，抗压强度下降很小。但其断裂方式及断面微观特征有明显变化。     

块状金属玻璃Zr55Cu30Al10Ni5的微压痕尺寸效应

本文根据Drucker-Prager屈服准则建立了适用于压敏材料的低阶应变梯度塑性(CMSG)理论。在此基础上,通过ABAQUS用户自定义材料子程序(UMAT)接口,建立了CMSG理论本构关系的有限元计算格式,结合该子程序对块状金属玻璃Zr55Cu30Al10Ni5的圆锥压痕响应进行了数值模拟,分析了不同压痕深度和压敏系数的影响。计算结果与实验数据吻合较好,表明该理论可以很好地描述金属玻璃Zr55Cu30Al10Ni5等一类材料的弹塑性行为。计算结果显示Zr55Cu30Al10Ni5的硬度随着压痕深度的增大而减小,由此说明基于Drucker–Prager屈服准则的CMSG理论可以很好地预测金属玻璃Zr55Cu30Al10Ni5在微尺度下表现出来的压敏尺寸效应。     

大块非晶合金数据库的开发

近年来，国际上关于大块非晶合金的研究取得了巨大的进展，积累了大量的研究数据及资料。大块非晶材料的研制及应用的关键在于寻求具有极大玻璃形成能力的大块非晶合金系统，以便可采用常规技术模铸成型。以计算材料科学和数据库为基础，开展计算机辅助合金成分设计将逐渐取代传统合金系统“试差”的研究方法。大块非晶合金数据库使大量繁杂凌乱的数据呈现系统化，规律化，涵盖大量有关大块非晶合金领域的研究数据资料及文献全文，具     

大块非晶合金的形成能力

通过对Ｚｒ－,Ｌａ－,Ｆｅ－,Ｍｇ－,Ｔｉ－,Ｎｄ－基合金系中,Ｔｒｆ,ΔＴｘ,Ｓ,Ｕ,Ｋｇｌ五个参数与临界冷却速度Ｒｃ之间关系的讨论来预测这些新型大块非晶形成合金的形成能力;结果发现参数Ｔｒｇ,Ｊ不能有效地反映这些合金系的ＧＦＡ,而参数ΔＴｘ,Ｓ,Ｋｇｌ较好地代表了这些大块非晶形成合金的ＧＦＡ。．     

铁磁性大块非晶合金的最新动向

根据国内外发表的最新文献详细介绍了利用缓冷凝固技术制备的铁磁性大块非晶合金的研究开发现状。     

Mg65Cu25Gd10大块非晶合金热稳定性研究

Mg65 Cu25 Gd10非晶合金的热稳定性关系到其作为结构材料的实用性及发展前景.利用差示扫描量热法(DSC)研究了预先弛豫退火处理后Mg65 Cu25 Gd10非晶的特征转变温度和晶化激活能变化,分析了弛豫退火对其热稳定性的影响.通过kissinger方程计算其晶化激活能、频率因子、反应速率系数进一步说明此非晶的晶化过程,并通过X射线衍射分析退火非晶的析晶过程,结果表明低温弛豫提高了非晶的热稳定性.     

Cyclic Fatigue Fracture of Zr55Al10Ni5Cu30 Bulk Amorphous Alloy with Quenched-in Crystallites

The effects of quenched-in crystallites on the fracture of bulk amorphous alloys under cyclic loading condition were investigated in this paper,For the fully amorphous alloy and specimen with fine crystallites the fatigue crack initiation occurred on the surface,For the specimen with larger cystallites the crack originated from a big broken crystallite near the surface,The average striation spacing on amorphous area is much larger than that on the crystallite Crack initiation occurred at the cystallites is due to that the brittle cyrstallites broke easily under cyclic deformation condition.The fine cystallites seemed to be protruded from the amorphous matrix and some bulges appeared on the surface of specimen with fine crystallites under cyclic loading.     

Pressure Effect on Crystallization of Zr55Cu30Al10Ni5 Bulk Metallic Glass

The effect of pressure on the variation of the crystallization phases of the Zr55u30Al10Ni5 bulk glass and its thermal stability under high pressure annealing was investigated by X-ray diffraction (XRD)and differential scanning calorimeter(DSC).The mode of crystallization and products of crystallization of the Zr55Cu30Al10Ni5 bulk glass were quite different pressure.At ambient pressure,the crystallization products consisted of NiZr2 and CuZr2,while at pressure of 1 Gpa and 3 Gpa,the alloys crystallized into NiZr2 and Cu10Zr7,respectively.The alloy was nearly not crystallized and only a small amount of Cu10Zr7 was precipitated under 5 Gpa.DSC proved that the mode of the crystallization under high pressure was different from that at ambient pressure.     

Thermal Relaxation and High Temperature Creep of Zr55Cu30Al10Ni5 Bulk Metallic Glass

The free volume model is applied to isothermal relaxation and hightemperature creep. For this analysis, the time dependent flow behaviourof Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass (BMG) near the glass transition temperature (T _g ) is expressed as a trade off between stress inducedgeneration and diffusion controlled annihilation of free volume. Thestrain rate-stress relation over a wide strain rate-range (10^–7to 10^–2 s^–1) was established for three different temperatures near T _g . It was found that the thermal relaxation behaviour and creep kinetics arecontrolled by the mobility of atoms with an activation energy of 161 kJ/mol.     

用渗流铸造法制备Zr55Al10Ni5Cu30非晶复合材料

用渗流铸造法制备出以Zr55Al10Ni5Cu30合金为基体，以W丝束为增强相的大块非晶复合材料，采用X-射线衍射分析了基体的相组成，在扫描电镜（SEM）下观察了反应界面的形貌，利用电子探针研究了元素的迁移情况，通过改变渗流温度和时间。研究了W丝和基体间界面的作用过程，选择适当的渗流温度和时间，可以制备出长65mm直径4.3mm的大块W丝束增强Zr55Al10Ni5Cu30非晶复合材料，在一定范围内提高渗流温度降低渗流时间或降低渗流温度延长渗流时间能得到同样的结果，在渗流铸造前，液态金属的过热有利于提高基体的非晶形成能力，降低渗流铸造时产生的缺陷。     

Diffusion bonding of Zr55Cu30Ni5Al10 bulk metallic glass to Cu with Al as transition layer

In this work we demonstrate the diffusion bonding of Zr₅₅Cu₃₀Ni₅Al₁₀ bulk metallic glass (BMG) to aluminum and copper alloy. The process parameters including temperature, pressure and time are investigated experimentally, and we obtain appropriate ones for accomplishing diffusion bonding of the BMG to aluminum alloy successfully. Then we present a two-step diffusion bonding process to bond the BMG to copper alloy by using aluminum alloy as transition layers, and achieve a five-layer bonded joint of BMG/Al/Cu/Al/BMG. The mechanical properties of the multilayer joint are examined. The hardness of the BMG in the joint is enhanced while the bending strength decreases significantly compared with the as-received BMG. Besides, the crystalline metals alleviate and block the extension of cracks in the BMG, which results in the joint fracturing in an explosion-proof glass manner, dissimilar to rupturing in a catastrophic manner that is always happened in the BMGs. Therefore, diffusion bonding of BMG to crystalline metals is a promising way to extend its application.     

大块非晶合金Zr55Cu30Al10Ni5的电子结构特征及电击穿行为

测定了大块非晶合金Zr55Cu30Al10Ni5晶化前后的费米能级和各元素的电子结合能,研究了非品合金的电子结构特征和电击穿行为．测试并讨论了非晶材料场发射能力和耐电压强度的关系．结果表明,对于Zr基合金,非品态比品态合金具有更大的功函数．比较了Zr55Cu30Al10Ni5合金非晶态与晶态的耐电压强度数值,发现非晶态合金的耐电压强度数值比较分散,品化合金的耐电压强度相对比较集中．耐电压强度平均值表明,Zr基合金非晶态具有更好的耐电压能力．     

Characterization,Removal and Evaluation of Oxide Film in the Diffusion Bonding of Zr55Cu30Ni5Al10 Bulk Metallic Glass

The composition of oxide film of ZrssCu3oNi5Al10 bulk metallic glass was identified by X-ray photoelectron spectroscopy. In addition, the relatively sound joints of bulk metallic glass without macroscopic deformation were obtained by removing the oxide film before diffusion bonding. The joint interfaces were observed by scanning electron microscopy and atomic force microscopy. The hardness of joints near the interface was higher than that far away from the interface, which is attributed to the difference of structural relaxation. According to the result of micro-focused X-ray diffractometry and transmission electron microscopy, the joints retained the amorphous structure when the holding time is less than 20 min. The surface area fraction of oxide film on the interface of joints was detected by ultrasonic inspection. Moreover, the surface area fraction of oxide film is in excellent agreement with the theoretical value calculated by shear strength. The result indicated that surface oxide film is the dominant barrier on the diffusion bonding of bulk metallic glass rather than low atomic diffusion coefficient.     

新型Zr57Nb5Cu15.4Ni12.6Al10大块非晶态合金的制备及其室温单轴压缩断裂行为

应用铜模真空吸铸法制备直径达5mm的棒状新型Zr57Nb5Cu154Ni12.6Al10大块非晶样品.X射线衍射检测证明样品完全为非晶态.通过等温示差扫描量热法(DSC)测试了Zr57Nb5Cu15.4Ni12.6Al10大块非晶的晶化动力学效应,同时研究了大块非晶合金的室温单轴压缩变形和断裂行为.结果表明:Zr57Nb5Cu15.4Ni12.6Al10块体非晶晶化过程具有动力学效应;其室温压缩变形过程主要表现为弹性变形;断裂面与压缩方向约呈45°,断口呈现典型的脉状花样.