Cu-Ni扩散偶的扩散溶解层

分别在普通和真空热处理炉中对Cu/Ni镶嵌式扩散偶进行退火热处理,利用扫描电子显微镜和电子探针显微分析仪观察和分析了扩散溶解层的形态和结构,并对其形成机理进行了探讨.结果表明,Cu/Ni扩散偶在950℃、100 h退火处理时,Cu/Ni扩散溶解层主要在Ni块上形成,形状依附于原始界面,并逐渐向Ni块基体延伸,与Ni块没有界面,其结构是以Ni为溶剂、Cu为溶质的间隙固溶体;扩散溶解层的形成机理是Cu原子向Ni块扩散,Ni原子几乎不向Cu丝扩散,Cu丝溶解在Ni块里面.     

Cu/Ni固相扩散界面的研究

采用彩色金相技术对“嵌入式”Cu/Ni扩散偶真空扩散处理时的界面迁移现象进行了观测,并研究了Cu/Ni界面间的扩散行为。结果表明,扩散偶在退火温度1123~1223K、保温时间25~150h(0·9×105~5·4×105s)的工艺条件下反应,Cu/Ni界面间结构由α/β转变为α/α′/β,其中α′为扩散层,实质是成分不均匀的固溶体,Cu/Ni界面间扩散行为是Kirkendall效应的一种显现,即界面上Cu和Ni元素均发生了扩散,但主要是Cu原子向Ni层的扩散。最后在试验数据基础上发现,扩散层厚度L与退火时间t之间满足抛物线L=K(t/t)n关系。     

退火条件对AgCuNi/TU1复合界面的影响

采用轧制复合法制备AgCuNi/TU1复合带材,使用EDS能谱仪分析不同退火条件下复合界面元素的扩散情况,利用两端不受扩散影响的扩散偶模型和Arrenius关系计算退火温度在550~750℃下Ag在TU1中的扩散系数、扩散常数与扩散激活能。结果显示:退火温度在550~750℃之间,分钟级退火时间下(退火时间5 min),AgCuNi/TU1复合界面主要发生表面原子扩散,且扩散系数和扩散常数在同一数量级,而扩散激活能有明显差别。     

稳恒强磁场对1420铝锂合金扩散连接性能及元素扩散的影响

采用金属镓作中间层,通过机械加压的方式制备了Al-Li/Al-Li和Al/Al-Li的扩散偶试样,在超导强磁场装置中对扩散偶试样进行真空热处理;通过剪切试验对经稳恒强磁场热处理后试样的连接强度进行了测试,通过EBSD和EDS对扩散偶界面处微观组织和界面附近Mg元素的含量与分布进行了观察与测量,并对1420铝锂合金中的Mg元素在1060纯铝中的扩散系数进行了计算. 结果表明,扩散连接接头抗剪强度随着磁感应强度的增加而增大,在热处理参数为:温度520 ℃、磁感应强度12 T、时间1 h时,接头抗剪强度达到最大188 MPa,为母材的94.2%,比无强磁场环境热处理的结合强度提高了168%;同时,随着磁感应强度的增加,1420铝锂合金中的Mg元素在1060纯铝中的扩散距离增加,扩散系数增大,12 T强磁场环境下比0 T(无磁场)环境下扩散系数提高了25%.     

Ni在过冷液态Zr_(48)Cu_(36)Ag_8Al_8非晶合金中的扩散行为（英文）

采用二次离子质谱(SIMS)以及透射电镜(TEM)研究在683~723 K温度范围内Ni原子在Zr48Cu36Ag8Al8非晶合金中的扩散行为。在过冷液相区内,Ni原子在Zr48Cu36Ag8Al8非晶合金中的扩散系数满足单一的Arrhenius关系式,具有较低的激活能,在过冷液相区内其扩展数系数是一个随退火时间变化的函数。此外,在界面附近有大量的纳米晶形成,其宽度大于通过二次离子质谱检测到的Ni原子扩散深度。结果表明:原子互扩散是促使界面纳米晶形成的重要因素。     

Ni-Nb-Ti三元系富Ni侧fcc相的互扩散及原子迁移率参数研究

本研究利用EPMA技术测定了Ni-Nb-Ti三元系富Ni侧合金在1000℃下的扩散数据,并使用Whittle and Green方法计算了Ni-Nb-Ti三元系在1000℃下的互扩散系数。通过DICTRA软件优化得到Ni-Nb-Ti三元系的fcc相的原子迁移率参数,运用优化得到的的原子迁移率计算出的互扩散系数与实验数据具有较好的一致性,从而验证了所得的原子迁移率参数的可靠性。同时通过运用迁移率参数拟合各扩散偶的的浓度-距离曲线和扩散路径,进一步验证了参数的合理性。     

Cu元素在二元等原子比合金中的扩散现象

研究了Cu₅₀Ni₅₀、Cu₅₀Co₅₀、Fe₅₀Ni₅₀、Fe₅₀Cr₅₀ 4种二元等原子比合金在镀铜并经850 ℃×10 h扩散处理后扩散层的显微组织及成分分布。结果表明,经过850 ℃×10 h扩散处理后,在Cu₅₀Ni₅₀等原子比合金中,由于适配空位的存在,Ni元素与Cu元素之间发生了明显的互扩散,并且Cu元素往往在晶界处发生互扩散;在Cu-Fe₅₀Ni₅₀扩散偶中,Cu元素和Fe元素之间发生了互扩散;但是在Cu-Fe₅₀Cr₅₀和Cu-Cu₅₀Co₅₀扩散偶中,各个元素均没有发生扩散。     

Ag/Cu钎焊复合带材轧制和退火研究

利用Ag-28Cu合金钎焊复合制备Ag/Cu复合材料,经轧制加工成复合带材。研究轧制变形和扩散退火对复合界面形貌、界面组织和性能的影响,以及界面元素扩散特征。结果表明,随着轧制变形量增加,Cu、Ag-28Cu和Ag发生协调变形,复合界面由波浪形,转变成锯齿状,最后Cu层整体向Ag层倾斜。随着加工率增加,Cu层硬度逐渐降低,Ag-28Cu层硬度显著升高,Ag层硬度不变。随着退火温度增加,界面组织逐渐长大粗化,复合层宽度增加。界面原子扩散行为主要是Cu原子向Ag中发生扩散,退火温度增加时,Ag-28Cu层中Cu原子向Ag侧逐渐减少,Ag层中的Cu原子含量增加,Cu和Ag层硬度没有发生变化,而Ag-28Cu层硬度逐渐降低。     

FCC Ni-Cu及Ni-Mn合金互扩散系数测定

结合扩散偶技术及电子探针微区分析技术,利用Sauer-Freise方法,得到FCC NiCu合金在1 123、1 273 K温度下的互扩散系数和Ni-Mn合金在1 273 K温度下的互扩散系数。实验证实互扩散系数是温度与成分的函数。利用所得互扩散系数外推得到1 123、1 273 K温度下Cu在Ni中的计算杂质扩散系数和1 273 K温度下Mn在Ni中的计算杂质扩散系数。     

退火过程中Ni的扩散行为

采用水溶液法在碳钢Q235表面电沉积Ni层,并利用管式退火炉对沉积试样进行退火,研究了不同退火条件下元素的分布、显微组织和断面层中Ni原子的扩散。通过数学解析得出Ni原子的扩散系数和扩散激活能。结果表明:在电沉积镍过程中所造成的镍在碳钢中基本未发生扩散;由于碳钢中微量元素很少,在退火扩散过程中对镍-铁扩散的影响可以忽略,近似的看成镍-铁扩散;镍含量与时间和深度关系为C_(Ni)=1/2[1-erf(x/2■)];镍的扩散系数与温度之间关系为lnD_(Ni)=-6273. 05·1/T-29. 268 93,扩散激活能Q=5. 2154×10~4J/mol。     

Simultaneous Measurement of Isotope-Free Tracer Diffusion Coefficients and Interdiffusion Coefficients in the Cu-Ni System

A new formalism recently developed by Belova et al., based on linear response theory combined with the Boltzmann–Matano method, allows determination of tracer and interdiffusion coefficients simultaneously from a single, isotope-free, traditional diffusion couple experiment. An experimental methodology with an analytical approach based on the new formalism has been carried out using the model Cu-Ni system to effectively determine tracer diffusion coefficients from an isotope-free diffusion couple experiment. Cu thin films were deposited in between several binary diffusion couples with varying terminal alloy compositions (Cu-25Ni, Cu-50Ni, Cu-75Ni, Ni). Diffusion couples were annealed at 800, 900 and 1000 °C, and the superimposed concentration profiles of thin film and interdiffusion were analyzed for the simultaneous determination of tracer and interdiffusion coefficients. Processed concentration profiles obtained from the diffusion experiments were also fitted with simple Gaussian distribution function. Results were compared to existing literature data obtained independently by radiotracer experiments, and an excellent agreement has been observed.     

Ni-Cr-W三元系富Ni侧fcc相的互扩散及原子迁移率参数研究

利用电子探针微量分析与Whittle-Green方法确定了在1200℃下退火72 h的Ni-Cr-W三元合金体系的互扩散系数。通过DICTRA软件包对实验互扩散系数进行评估以确定原子迁移率。通过全面分析比较模型预测的扩散特性和实验数据的良好一致性验证了原子迁移率的合理性。Ni-Cr-W三元体系中的扩散现象,如扩散路径和浓度-距离曲线可以通过获得的原子迁移率合理地描述,进一步证明了本研究所获得的原子迁移率参数的可靠性。     

Solid state diffusion in Cu–Sn and Ni–Sn diffusion couples with flip-chip scale dimensions

The formation and growth rate of intermetallics of frequently used metallisation systems for flip-chip bumping have been studied and are reported for many years. However, no data are available on diffusion couples with flip-chip processing methods and actual flip-chip scale dimensions. In this paper, the interdiffusion coefficients and activation energies of Cu–Sn and Ni–Sn intermetallic formations are measured on flip-chip bumps with 40 μm bond pad diameter. Also the morphology of the metallurgical reactions is described. Furthermore, the ideal case of a binary diffusion system is seldom present in real-life. In practice, the presence of additional alloying elements has an impact on the intermetallic stoichiometry and even on intermetallic growth and morphology. It is shown that small quantities of Cu in a Ni–Sn system can have a beneficial effect on the Ni consumption but larger quantities result in extreme scalloping of the intermetallic interface.     

Interdiffusion and Atomic Mobility Studies in Ni-Rich fcc Ni-Co-Al Alloys

The ternary interdiffusion coefficients in fcc Ni-Co-Al alloys at 1373 K were determined using Whittle and Green method together with electronic-probe microanalysis. With the help of DICTRA software, the experimental diffusion coefficients were critically assessed to obtain the atomic mobilities of Ni, Co and Al in fcc Ni-Co-Al alloys. Comprehensive comparisons between calculated and experimental diffusion coefficients showed that the experimental data could be well reproduced by the atomic mobilities obtained in the present work. The developed diffusion mobilities were further validated by the calculation of the concentration profiles and diffusion paths in diffusion couples.     

Expressions for vacancy-wind factors occurring in interdiffusion in ternary and higher-order alloys

In this paper, an analysis of the vacancy-wind factors occurring in the expression relating interdiffusion and tracer diffusion coefficients in ternary (and higher-order) alloys is provided for the first time. It is shown that for the ternary alloy the vacancy-wind factors occur as a matrix of four elements. The diffusion kinetics formalism developed by Manning for a random alloy is used to find closed-form expressions for the vacancy-wind factors in terms of the tracer diffusion coefficients. These reduce to the well-known expression for the vacancy-wind factor occurring in the expression relating interdiffusion and tracer diffusion coefficients in the binary random alloy. The more recent self-consistent diffusion kinetics formalism of Moleko, Allnatt and Allnatt (which is near exact) is also used to calculate the vacancy-wind factors from the tracer diffusion coefficients. It is found that the off-diagonal vacancy-wind factors can actually be negative with high absolute values. Accordingly, the use of the Darken approach (which ignores the off-diagonal phenomenological coefficients) to modelling of the interdiffusion process would then give an incorrect direction of the cross-terms in the corresponding interdiffusion flux expressions. Tracer diffusion data in the ternary Cu–Fe–Ni and Cu–Ni–Zn systems are used to calculate the vacancy-wind factors in these systems.     

Intrinsic diffusion and Kirkendall effect in Ni–Pd and Fe–Pd solid solutions

Intrinsic diffusion and the Kirkendall effect in the Ni–Pd (at 900–1200°C) and Fe–Pd (at 1100°C) solid solution systems were investigated. The diffusion couple technique including incremental and “multi-foil” couples was employed. A theoretical analysis of the Kirkendall effect, which manifests itself by migration of inert markers inside the interdiffusion zone, was performed for a binary solid solution system. It was demonstrated that depending upon the relative mobilities of the components in different parts of the interaction zone of such binary diffusion couples, the appearance of two or more “Kirkendall” planes as marked by inert particles can be expected. This phenomenon, which indeed was predicted and found in the multiphase Ni/Ti diffusion couple, was not observed in the experiments on the single-phase Ni–Pd and Fe–Pd systems. The diffusion process in these binary systems exhibiting a minimum in the liquidus curve was found to show special features with respect to the concentration dependence of the diffusion coefficients.     

Determination and assessment of ternary interdiffusion coefficients from individual diffusion couples

Two pairs of diffusion couples were assembled with α (fcc) Cu-Ni-Zn alloys characterized by similar thermodynamic activities for Cu and annealed at 775 °C. One pair of couples exhibited intersecting diffusion paths, and the other pair showed overlapping path segments. They were analyzed for interdiffusion fluxes, zero-flux-planes, and ternary interdiffusion coefficients directly from the concentration profiles. The analysis was based on converting profiles of concentrations to profiles of interdiffusion fluxes and evaluating moments of interdiffusion fluxes for the determination of interdiffusion coefficients over selected composition ranges. For the pair with intersecting diffusion paths, ternary interdiffusion coefficients were determined from the individual couples in the region of their common composition; these coefficients were in agreement with each other and with those determined by the Boltzmann-Matano analysis. For the pair of couples with overlapping diffusion path segments, interdiffusion coefficients calculated from each couple over the common path segment agreed with each other. In addition, the interdiffusion coefficients calculated over various composition regions were used to regenerate the concentration profiles of the individual couples. All calculations were carried out with the aid of a computer program called MultiDiFlux, which was developed by Dayananda and Ram-Mohan as a free educational and research tool for analysis of multicomponent diffusion.     

Interdiffusion and Atomic Mobilities in bcc Ti-Ga and Ti-Cu Alloys

On the basis of three groups of Ti/Ti-10 at.% Ga and Ti/Ti-7 at.% Cu diffusion couples, respectively, interdiffusion coefficients in the bcc Ti-Ga and Ti-Cu binary alloys in the temperature range of 1273-1573 K were evaluated by means of the den Broeder method. Based on various reported experimental and the present measured diffusion coefficients as well as the available thermodynamic information, accurate atomic mobilities in the bcc Ti-Ga and Ti-Cu alloys were assessed via the DICTRA simulation package. A semi-empirical correlation was employed in the present work for the self-diffusivities in the hypothetical bcc Ga and Cu. Comparision between the calculated and measured diffusion coefficients indicated that most of the experimental information can be reasonably reproduced. The developed diffusion mobilities were further validated by the prediction of the concentration-distance profiles.