Sn/Ni液/固扩散偶的界面反应

用Sn／Ni液／固扩散偶研究了Sn液体和Ni基体之间的界面反应和生成相序列。结果表明：Sn／Ni液／固扩散偶在773K退火，其液／固界面上首先生成Ni3Sn4相。而在873K退火15min，首先生成Ni3Sn2-HT（高温）相；再随退火时间延长至60min，在液相和Ni3Sn2-HT的界面上生成Ni3Sn4相；当退火时间再次延长至240min，又在Ni3Sn2—HT相与fee（Ni）的界面上生成Ni3Sn相。采用最大驱动力模型，利用Thermo-Calc软件和已有的Ni-Sn二元数据库对Sn／Ni液／固扩散偶的界面反应过程和生成相序列进行了计算与预测，预测结果和实验结果吻合良好。     

Equilibrium distribution of Fe,Ni, Sb,and Sn between liquid Cu and a CaO-rich slag

Equilibrium measurements of the distribution of Fe, Ni, Sb, and Sn between a liquid Cu-O solution and a CaF₂-CaO-MgO-SiO₂ were carried out at 1500 K in a magnesia crucible. The results show that the studied solutes were in the states Fe(III), Ni(II), Sb(III), and Sn(IV), in the slag, for metal O contents ranging from 100 ppm to saturation at 2.1 pct. The Cu oxide solubility in the slag was also measured in absence of the solute elements. Its maximum solubility is about 4 ± 1 mass pct Cu₂O. The compositions at equilibrium allow determination of the activity coefficients (referred to pure oxide) of the four solute oxides in the slag. These values, expressed in round figures to take into account the experimental uncertainties, are 10 for Fe₂O₃, 20 for NiO, 10 for SnO₂, 1.6 10⁻² for SbO_1.5, and 60 for Cu₂O.     

Thermodynamic measurements in liquid Sn−Ag Alloys

The reversible galvanic cell: $$ Sn(l), SnO_2 (s)/CaO - ZrO_2 /Sn - Ag(1),SnO_2 (s) $$ electrolyte was employed to determine the thermodynamic properties of liquid Sn?Ag Alloys in the range ofX _Sn from 0.2 to 0.9 and in the overall temperature range of 825° to 1111°K. The data are consistent with the phase diagram. At 900°K, tin shows both positive and negative deviations from Raoult’s law, anda _Sn values agree well with the determinations of Frantik and McDonald but not with those of Laurieet al. At 1100°K, both tin and silver exhibit negative deviations from Raoult’s law lines.     

An analysis of interdiffusion in finite-geometry,two-phase diffusion couples in the Ni−W and Ag−Cu systems

The progress of homogenization in finite, multilayer diffusion couples was studied experimentally using both quantitative metallography to measure phase thicknesses and electron microprobe analysis to determine concentration-distance profiles. Ni?W couples having mean compositions in the nickel-rich terminal solid solution range (12.1 and 15.2 at. pct W) were studied after 4.43 to 240.7 hr interdiffusion treatments at 1156° and 1207°C. Ag?Cu couples having mean compositions in both of the terminal solid solution ranges (8.5 at. pct Cu and 2.1 at. pct Ag) were studied after 3.8 to 65.4 hr interdiffusion treatments at 760°C. Experimental data were in good agreement with calculations of interdiffusion based on equilibrium interface concentrations and concentration-independent interdiffusion coefficients. The good agreement between experimental data and calculated values for the Ni?W couples extended to times necessary for the achievement of essentially complete homogenization,i.e., through both the two-phase dissolution process and the subsequent stage of gradient elimination in the terminal solid solution phase.     

The diffusion of hydrogen in liquid iron alloys

Rates of absorption of hydrogen in stagnant liquid iron and ten (Fe-X) binary iron alloy systems were studied by an unsteady-state gas-liquid metal diffusion cell technique. These rates were found to be controlled by diffusion of hydrogen in the liquid phase. Chemical diffusion coefficients (D _h) were measured in pure iron and Fe-X alloys in the following (at. pct) composition ranges: Mn (0 to 5), Cr (0 to 25), V (0 to 25), Nb (0 to 10), Mo (0 to 25), W (0 to 5), Ni (0 to 75), Co (0 to 75), Sn (0 to 10), and Cu (0 to 25). All measuredD _H values at 1600°C lie between 7 × 10^-4 and 16 × 10^-4 sq cm per sec. The diffusion coefficients found for pure iron can be represented by D_H ^Fe = 4.37 × 10⁻³ exp (−4134 ± 1012)/RT cm²/sec where the uncertainty in the activation energy, Q, in cal per mole, corresponds to the 90 pct confidence level. A linear relationship was found between the logarithm of the hydrogen diffusion coefficient D_H ^Fe-X and the interaction parameter ε_H ^X for low and medium concentrations of alloying elementX, when applied to a fixed concentration ofX(5 or 25 at. pct) and to individual periods in the periodic table. A useful linear correlation also appears to exist between logD_H ^Fe-X and hydrogen solubility for fixed concentration ofX and with respect to the period in whichX is found. Formerly Research Assistant, Department of Mineral Engineering, Stanford University, Stanford, Calif. This paper is based upon a thesis submitted by P. J. DEPUYDT in partial fulfillment of the requirements of the degree of Doctor of Philosophy at Stanford University and part of a presentation made at the 1970 Annual AIME Meeting.     

Solubility of hydrogen in solid Ni−Co and Ni−Cu alloys

The solubility of hydrogen was measured in solid Ni, Co, and Cu, and in the Ni?Co and Ni?Cu systems. A unique sampling technique was used in which equilibrated specimens were quenched by dropping into mercury. The measurements were made as a function of temperature in the range from 700° to 1225°C and of hydrogen pressure, up to 1 atm. Dissolved hydrogen in all metals and alloys obeyed Sieverts' Law. An attempt was made to correlate the hydrogen solubility with solution models based on the electronic structure of the alloys. A nonlinear correlation was found with the electronic specific heat coefficient which relates to the density of states at the Fermi surface.     

Kinetics of wetting Ag and Cu substrates by molten 60Sn40Pb

The time and temperature dependence of wetting Cu and Ag substrates by molten 60Sn40Pb drops was determined using several fluxes. Four stages were identified. In Stage I, the solder melts and develops into a spherical cap, which spreads rapidly to the quasi-equilibrium stage II, wherein the contact angle θ changes only slightly with time. This is followed by stage III, where6 decreases with a time exponent of ≈0.2, leading ultimately to stage IV, where θ again changes only little with time. An intermetallic compound was observed at the liquid/solid inter-face throughout stages II to IV. The flux influenced the magnitude of θ and the small time dependence in stage II. For a nonactivated rosin flux, the temperature dependence of θ_II yielded an apparent activation energy Q^II _a = 2 to 3 kcal/mole for all substrates, including pretinned Cu. It is speculated that the driving force for the decrease in θ during stage III may result from a decrease in the free energy of the system by diffusion, with a corresponding change in one or more of the interfacial tensions. Pretinning Cu, which formed the intermetallic compound Cu3Sn on the surface, had a significant effect on the time dependence of θ, the effect in stage II being relatively greater than in stage III.     

镧对Sn3.5Ag0.5Cu钎料组织和性能的影响

运用莱卡显微镜、扫描电镜和能谱分析等仪器设备,研究添加微量La对Sn3.5Ag0.5Cu钎料组织性能的影响.结果表明,La能显著细化Sn3.5Ag0.5Cu钎料及其与Cu基体焊合后的IMC的显微组织,钎料剪切强度提高10.9%;键参数函数计算结果表明La具有"亲Sn"倾向,可降低IMC的长大驱动力.     

Plane strain compression of copper,Cu 6wt Pct Al,and Ag 4wt pct Sn crystals

Crystals of various orientations were forced to undergo plane-strain compression to simulate the deformation of a grain in a polycrystalline aggregate. Copper, Cu?6wt pct Al, and Ag?4wt pct Sn were studied to evaluate the influence of stacking fault energy on the model of G. I. Taylor which assumes equal hardening on all slip systems. The compression stress strain (σ?∈) curves were converted to resolved shear-stress: shear-strain (τ?γ) using the appropriate Taylor factor. A quantitative analysis of lattice rotation during deformation was made and found to be in agreement with the orientation change determined with the aid of X-ray pole figures. The change in Taylor factor associated with the reorientation was computed and used in constructing the τ?γ curves. Additional information on the active slip and twin systems was provided by optical metallography. The τ?γ curves generally fell into a narrow band for all these materials, indicating that the assumption of equal hardening was reasonably valid for low stacking fault energy alloys under conditions of multiple slip imposed in the present experiment. Deviations occurred mainly in the alloy crystals which exhibited mechanical twinning. Nevertheless, the active twin systems in these crystals were satisfactorily predicted by an extended Taylor analysis.     

铂饰品中Pt, Pd, Au, Ag, Cu, Ni, Zn, Fe的测定

试验研究建立了同一试料溶液连续、同时测定铂饰品中各成分的分析方法。主体Pt以氯铂酸铵称量法及火焰原子吸收光谱(FAAS)法或电感耦合等离子发射光谱(ICP-AES)法测定滤液中残留Pt进行补差而测定。主成分Pd,Au,Ag,Cu和焊料成分Ni,Zn,Fe以FAAS法或ICP-AES法测定。其方法回收率分别为:Pt99.9%~100%;Pd99.3%~99.7%;Au99.5%~l01.5%;Ag98.0%~100%;Cu97.7%~99.3%;Zn98.0%~99.0%;Ni94.0%~105%;Fe95.0%~99.0%。实际试样分析时,各成分质量分数之和一般在99.12%~l01.2%之间,接近于100%,间接说明方法的可靠性。本法适用于Pt-Pd二元体系和Pt-Pd-Au-Cu多元复杂体系的铂饰品的破坏分析,可用于校正X荧光光谱法无损检测铂饰品的分析结果。     

Room-temperature diffusion in Cu/Ag thin-film couples caused by anodic dissolution

Thin, 100-nm films of first silver and then copper were deposited consecutively onto inert substrates by magnetron sputter deposition. Constant anodic current densities were applied at room temperature to dissolve the outer copper film to varying depths. The 50Cu/50Ag interface, derived from the auger electron spectroscopic concentration-depth profile, initially moved into the copper toward the outer dissolving surface, indicating enhanced diffusion of copper into silver. After longer times at all anodic current densities, the interface reversed and moved back toward the underlying silver-rich layer, indicating that eventually diffusion of silver into copper predominated. The reversal time was inversely proportional to the anodic current density. These effects are explained by anodic formation of subsurface vacancies which migrate as divacancies to the copper/silver interface where they affect interface movements by the well-known Kirkendall mechanism. Calculated diffusivities up to 10⁻¹² cm²/s at maximum anodic current densities of 900 μA/cm² are dramatically above any that are normally observed at room temperature.     

Room-temperature diffusion in Cu/Ag thin-film couples caused by anodic dissolution

Thin, 100-nm films of first silver and then copper were deposited consecutively onto inert substrates by magnetron sputter deposition. Constant anodic current densities were applied at room temperature to dissolve the outer copper film to varying depths. The 50Cu/50Ag interface, derived from the auger electron spectroscopic concentration-depth profile, initially moved into the copper toward the outer dissolving surface, indicating enhanced diffusion of copper into silver. After longer times at all anodic current densities, the interface reversed and moved back toward the underlying silver-rich layer, indicating that eventually diffusion of silver into copper predominated. The reversal time was inversely proportional to the anodic current density. These effects are explained by anodic formation of subsurface vacancies which migrate as divacancies to the copper/silver interface where they affect interface movements by the well-known Kirkendall mechanism. Calculated diffusivities up to 10⁻¹² cm²/s at maximum anodic current densities of 900 μA/cm² are dramatically above any that are normally observed at room temperature.     

Characterization of diffusion induced grain boundary migration in the Ag/Cu system

The phenomenon of diffusion induced grain boundary migration (DIGM) when silver diffuses along copper's grain boundaries was confirmed through the characterization of the microstructure and the morphology of the migrated boundaries, the discontinuity and asymmetric character of the concentration profile, the dislocation configuration and the kinetics of migration by means of SEM, EPMA, TEM and AEM. The experimental results were discussed to prove the existence and the characteristics of DIGM in Ag/Cu system.     

The Solution Chemistry and Solvent Extraction Behaviour of Cu,Fe, Ni,Zn, Pb,Sn, Ag,As, Sb,Bi, Se and Te in Acid Chloride Solutions Reviewed from the Standpoint of PGM Refining

In the solvent extraction separation of Platinum Group Metals (PGM) from industrial chloride liquors, the presence of impurity elements may cause processing complications as they tend to coextract. Strip solution contamination may be an obvious occurence as well as buildup in the organic phase and third phase formation. In order to design scrubbing stages for their removal or to avoid coextraction altogether, it is important to have a solid understanding of the chloro-chemistry of the impurity elements. In addition, reviewing the chloride solvent extraction systems previously investigated provides additional information for process design. The review covers the elements Cu, Fe, Ni, Zn, Pb, Sn, Ag, As, Sb, Bi, Se and Te. Most elements exhibit anionic chlorocomplexation in HCl medium at >1.0 M and this is why they extract via an ion-pair formation mechanism with strong basic extractants (amines)as well as weaker ones (TBP, TOPO, 8-hydroxyquinoline)