Phase transformation and morphology of the intermetallic compounds formed at the Sn–9Zn–3.5Ag/Cu interface in aging

The morphology and phase transformation of the intermetallic compounds (IMCs) formed at the Sn–9Zn–3.5Ag/Cu interface in a solid-state reaction have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The monoclinic η′-Cu₆Sn₅ transforms to the hexagonal η-Cu₆Sn₅ and the orthorhombic Cu₅Zn₈ transforms to the body-centered cubic (bcc) γ-Cu₅Zn₈ as aged at 180 °C. The scallop-shaped Cu₆Sn₅ layer is retained after aging at 180 °C for 1000 h. In the solid-state reaction, Ag is repelled from η′-Cu₆Sn₅ and reacts with Sn to form Ag₃Sn, and the Cu₅Zn₈ layer decomposes. Kirkendall voids are not observed at the Sn–9Zn–3.5Ag/Cu interface even after aging at 180 °C for 1000 h.     

Investigations of interfacial reactions of Sn–Zn based and Sn–Ag–Cu lead-free solder alloys as replacement for Sn–Pb solder

The interfacial reactions of Sn–Zn based solders and a Sn–Ag–Cu solder have been compared with a eutectic Sn–Pb solder. During reflow soldering different types of intermetallic compounds (IMCs) are found at the interface. The morphologies of these IMCs are quite different for different solder compositions. As-reflowed, the growth rates of IMCs in the Sn–Zn based solder are higher than in the Sn–Ag–Cu and Sn–Pb solders. Different types of IMCs such as γ-Cu₅Zn₈, β-CuZn and a thin unknown Cu–Zn layer are formed in the Sn–Zn based solder but in the cases of Cu/Sn–Pb and Cu/Sn–Ag–Cu solder systems Cu₆Sn₅ IMC layers are formed at the interface. Cu₆Sn₅ and Cu₃Sn interfacial IMCs are formed in the early stages of 10 min reflow due to the limited supply of Sn from the Sn–Pb solder. The spalling of Cu–Sn IMCs is observed only in the Sn–Ag–Cu solder. The size of Zn platelets is increased with an increase of reflow time for the Cu/Sn–Zn solder system. In the case of the Sn–Zn–Bi solder, there is no significant increase in the Zn-rich phases with extended reflow time. Also, Bi offers significant effects on the wetting, the growth rate of IMCs as well as on the size and distribution of Zn-rich phases in the β-Sn matrix. No Cu–Sn IMCs are found in the Sn–Zn based solder during 20 min reflow. The consumption of Cu by the solders are ranked as Sn–Zn–Bi > Sn–Ag–Cu > Sn–Zn > Sn–Pb. Despite the higher Cu-consumption rate, Bi-containing solder may be a promising candidate for a lead-free solder in modern electronic packaging taking into account its lower soldering temperature and material costs.     

电迁移对Ni/Sn3.0Ag0.5Cu/Cu焊点界面反应的影响

研究了温度为150℃,电流密度为5.0×10³A/cm²的条件下电迁移对Ni/Sn3.0Ag0.5Cu/Cu焊点界面反应的影响.回流焊后在Sn3.0Ag0.5Cu/Ni和Sn3.0Ag0.5Cu/Cu的界面上均形成了（Cu,Ni）₆Sn₅型化合物.时效过程中界面化合物随时效时间增加而增厚,时效800 h后两端的化合物并没有发生转变,仍为（Cu,Ni）₆Sn₅型.电流方向对Cu基板的消耗起着决定作用.当电子从基板端流向芯片端时,电流导致基板端Cu焊盘发生局部快速溶解,并导致裂纹在Sn3.0Ag0.5Cu/（Cu,Ni）₆Sn₅界面产生,溶解到钎料中的Cu原子在钎料中沿着电子运动的方向向阳极扩散,并与钎料中的Sn原子发生反应生成大量的Cu₆Sn₅化合物颗粒.当电子从芯片端流向基板端时,芯片端Ni UBM层没有发生明显的溶解,在靠近阳极界面处的钎料中有少量的Cu₆Sn₅化合物颗粒生成,电迁移800 h后焊点仍保持完好.电迁移过程中无论电子的运动方向如何,均促进了阳极界面处（Cu,Ni）₆Sn₅的生长,阳极界面IMC厚度明显大于阴极界面IMC的厚度.与Ni相比,当Cu作为阴极时焊点更容易在电迁移作用下失效.     

Sn-9Zn-0.1S/Cu焊点液固界面金属间化合物的生长动力学

采用扫描电镜和光学显微镜观察研究了230~260℃焊接温度范围内Sn-9Zn-0.1S/Cu焊点界面金属间化合物的结构及生长动力学.结果表明,在该焊点界面形成的化合物可分为两层:靠铜侧的是厚且平直的γ-Cu₅Zn₈化合物层;靠焊料侧的则为另一薄且呈扇贝、粒状的CuZn化合物层.提高钎焊温度及延长反应时间基本不改变Sn-9Zn-0.1S/Cu焊点界面金属间化合物的结构和成分,但会使形成的界面金属间化合物层厚度增加.γ-Cu₅Zn₈金属间化合物层的厚度与反应时间的平方根呈线性关系,表明其生长由扩散机制控制.根据阿伦尼乌斯公式,Sn-9Zn-0.1S/Cu焊点界面γ-Cu₅Zn₈金属间化合物层反应活化能为22.09 kJ/mol.     

Anomalous enhancement of g-shift in κ-type BEDT-TTF compounds

Systematic investigation of the ESR properties of κ-type BEDT-TTF compounds has been carried out. The salts with crystal symmetry of P2₁, κ-CU(NCS)₂,κ-CU(CN)[N(CN)₂] and κ-Ag(CN)₂·H₂O, were found to show an anomalous enhancement of g-shift below about 130K when the static field was applied along b axis. Concomitantly, abrupt broadening of the linewidth has been observed in all principal axes. On the other hand, κ-Cu[N(CN)₂]Br (Pnma) and κ′-Cu₂(CN)₃ (P2₁/c) have almost temperature independent g-values for all field directions. We discuss the possible explanation of the anomalous enhancement of the compounds with P2₁ space group.     

The ternary system Au---Co---Sn and the crystal structure of AuCo2(1−a)Sn4

The phase relations in the ternary system Au---Co---S have been studied by powder X-ray diffraction, metallography, electron microprobe analysis, and thermal analysis. The condensed phases occurring, tie-lines and tie-triangles are presented for an isothermal section of the phase diagram at 380°C. A hitherto unknown genuine ternary phase AuCo_2(1−a)Sn₄ is found, with 0.167 u 0.180, and as indicated by the formula, the non-stoichiometry is of the subtractional kind (confirmed by density measurements). The unit cell is monoclinic (space group C2/m) with a = 1260.3(3), B = 421.3(1), C = 522.9(1) pm and β = 104.62(2)° for u = 0.167. Au in 2a: (0.833) Co, Sn(I) and Sn(II) in 4i with x = 0.2116(2), Z = 0.3331(5) for Co, x = 0.41759(9), Z = 0.6493(2) for Sn(I) and x = 0.18489(9), Z = 0.8142(2) for Sn(II). The structure of AuCo_2(1−a)Sn₄ is of the Ni_3−xSn₄ type and its atomic arrangement is discussed in relation to that of the prototype. AuCo_2(1−a)Sn₄ behaves as a virtually ideal Curie paramagnet with μ_p = 1.191(3) μ_u per Co atom.     

β-phase transformation and thermoelectric power in FeSi2 and Fe2Si5 based alloys containing small amounts of Cu

The effects of Cu addition on the β phase formation rate and the thermoelectric power in various FeSi₂ and Fe₂Si₅ based alloys was examined. The peritectoid reaction (a+→β) in FeSi₂ alloys was initially enhanced by the addition of Cu but it became slower for longer annealing times. The retained metallic ε was harmful for the thermoelectric power. The inherent thermoelectric properties of (FeSi₂)_99−XMn₁Cu_X (X=0–1.O at.%), (FeSi₂)_99−X Co₁Cu_X (X=0–1.0 at.%) alloys were attained after the elimination of ε. In the case of eutectoid reaction (→β+Si). Differential thermal analysis, X-ray diffraction and microscopic observation clearly confirmed that the eutectoid reaction rate was drastically enhanced by the addition of a small amount of Cu and its rate decreased with decreasing Cu content. The rate also depends on the annealing temperature and reached a maximum at about 1073 K for most alloys. The addition of only 0.1 at.% Cu was still very effective even in Mn or Co doped alloys. The thermoelectric power of these alloys increased very quickly with annealing time. Their final values decreased with Cu content and saturated at 0.2 at.% Cu. The value of the 0.1 at.% Cu added alloy was higher than that of both the conventional p- and a-type FeSi₂ based alloys. These results suggest that the Fe₂Si₅ alloys with a small amount of Cu may be attractive as new thermoelectric materials.     

In situ TEM observation of dislocation motion in thermally strained Al nanowires

Al thin films deposited epitaxially on (0001) -Al₂O₃ substrates, have been thinned cross-sectionally to form Al nanowires. The Al wires, consisting of two Σ3 twin variants, have been strained in situ by differential thermal expansion between the Al wires and the Al₂O₃ substrate during transmission electron microscopy heating. Dynamical observations show that maximum dislocation activity occurs in the first heating cycle up to 400°C, with decreasing activity during further cycles. The {111} Al || (0001) -Al₂O₃ interface acts as a source of dislocation half-loops. The motion of threading dislocations along the wires generates long trailing dislocation segments parallel to, and offset from, the {111} Al || (0001) -Al₂O₃ interface. Dislocation multiplication occurs by the reaction of half-loops and extended threading dislocation segments at the wire boundaries and substrate interface. The Σ3 twin grains bisecting the wires are observed to be stable during thermal cycling to 400°C, and their { } boundaries are weak pinning sites.     

Effect of CuO Particle Size on the Microstructure Evolution of Al_2O_(3P)/Al Composites Prepared Via Displacement Reactions in the Al/CuO System

An Al2O3P/Al composite was successfully synthesized using a displacement reaction between 80 wt% Al and20 wt% Cu O powders at a heating rate of 5 °C/min. Two different sizes Cu O particles were used, and all the experiments were conducted under an argon atmosphere. To analyze the microstructural evolution during synthesis, the Al–20 wt%Cu O samples were heated to the temperatures selected according to the differential scanning calorimetry curve and then immediately quenched with water. The phase composites and microstructure of the water-quenching samples were investigated using X-ray diffraction, optical microscopy, scanning electron microscopy and energy-dispersive spectrometry.The results indicate that the Cu O particle size has a significant effect on the microstructural evolution of the samples during the heating stage and on the microstructure of synthesized composites. Smaller Cu O particles can decrease the reaction temperature, narrow the reaction temperature range at the different reaction stages during the heating stage and make the size and distribution of in situ Al2O3 particles more uniform. The reaction between Al and Cu O can be complete as the temperature rises to 900 °C. The size of the in situ Al2O3 particles is approximately 5 lm when the size of the Cu O particles is less than 6 lm. This sample has a relatively high Rockwell hardness of 60 HRB.     

Effect of Annealing on the Morphology,Structure and Photoelectric Properties of AZO/Pt/FTO Trilayer Films

Aluminum-doped zinc oxide/platinum/fluorine-doped tin oxide(AZO/Pt/FTO) trilayer films were prepared by sputtering 5-nm-thick Pt layers and 150-nm-thick AZO layers in sequence on commercial FTO glass.The effects of onestep annealing and layer-by-layer annealing on the morphology,structure and photoelectric properties of the AZO/Pt/FTO trilayer films were comparatively analyzed.It is found that the both annealing approaches increased the grain size and improved the crystallinity of the films,leading to enhancement in transmittance and conductivity.However,layer-by-layer annealing led to the formation of quasi-continuous or continuous AZO layers,different from the sparsely distributed AZO particles brought about by one-step annealing,resulting in excellent optical and electrical properties.Specifically,after layer-by-layer annealing at 400 ℃ for both Pt and AZO layers,the AZO/Pt/FTO trilayer film showed an increase in average transmittance from 71.3% to 85.3% and a decrease in sheet resistance from 7.5 to 5.6 Ω/□,leading to the highest figure of merit of 3.64 × 10~(-2) Ω~(-1).     

Determination and Analysis of Optical Constant of Annealed Sn_2Sb_2S_5 Thin Films

The effects of annealing on structural, optical and electrical properties of Sn2Sb2S5 thin films were studied.Sn2Sb2S5 thin films were deposited on no-heated glass substrates by single source vacuum evaporation method. The asdeposited films were annealed in air for 1 h at 100, 200 and 300 °C. XRD study shows that annealed films are crystallized according to the preferential orientation(602). Optical measurements show that the thin films have relatively high absorption coefficients in the range of 105–106cm-1in the energy range of 2–3.25 e V. It is also found that Sn2Sb2S5 exhibit two optical direct transitions. The models of Wemple–Di Domenico and Spitzer–Fan were applied for the analysis of the dispersion of the refractive index and the determination of the optical and dielectric constants. The electrical resistivity measurements are recorded, and two activation energy values are determined. The layers annealed at 200 and300 °C exhibit a resistive hysteresis behavior. The properties reported here offer perspective to Sn2Sb2S5 for its application in many advanced technologies.     

Devitrification of Al-Ce Amorphous Ribbon Investigated Using In situ High Energy X-ray Diffraction

Metastable phases formed during vitrification or devitrification open an avenue to study the intrinsic structural hierarchy in amorphous materials. The phase transformation sequence of Al89Ce11 amorphous ribbon was investigated using differential scanning calorimetry, in situ high energy X-ray diffraction (HEXRD) and ex situ high-resolution scanning transmission electron microscope. The results reveal the devitrification pathway following the reaction: amorphous → ε-Al₆₀Ce₁₁ +  fcc-Al → η-Al₄₁Ce₅ +  fcc-Al → Al₁₁Ce₃ +  fcc-Al. It has been found that both ε-Al₆₀Ce₁₁ and η-Al₄₁Ce₅ metastable phases have same Ce-centered 1-6-6-6-1 motif, suggesting that the structural motif can be inherited. Formation of metastable phase with large unit cell is related to the short-range orders developed during solidification. Structural heredity provides a new method to tailor the microstructure and properties of Al-based alloys based on genetic mechanism.     

盐酸伊伐布雷定片人体药动学研究

目的: 研究盐酸伊伐布雷定片在中国健康志愿者中的单次及连续多次给药药动学特征。方法: 12例受试者采用随机开放二重3×3拉丁方试验设计,研究单次及连续多次给药药动学特征;采用LC-MS/MS法测定血浆中伊伐布雷定及其活性代谢产物S-18982的药物浓度。药动学参数采用WinNonlin软件计算。结果: 单次(5、10、15 mg)给药后伊伐布雷定的主要药动学参数:C_max分别为(19±10)、(47±24)、(79±41) μg/L,t_max分别为(0.7±0.5)、(0.6±0.3)、(0.5±0.1) h; AUC_last分别为(58±32)、(138±83)、(189±115) μg·h·L^-1;AUC_inf分别为(59±32)、(140±84)、 (191±116) μg·h·L^-1;其活性代谢产物S-18982的主要药动学参数:C_max分别为(3.1±1.2)、(7.9±2.8)、(15.0±5.4) μg/L; t_max分别为(1.1±0.8),(0.8±0.4),(0.6±0.1) h;AUC_last分别为(17±8)、 (47±19)、 (76±29) μg·h·L^-1;AUC_inf分别为(20±8)、(52±21), (85±30) μg·h·L^-1。连续多次给药 5 mg 后伊伐布雷定的主要药动学参数:C_max(20±7) μg/L;t_max(1.0±0.7) h; AUC_last( 67±32) μg·h·L^-1; AUC_inf (69±33) μg·h·L^-1;其活性代谢产物S-18982的主要药动学参数:C_max(4.5±1.3) μg/L;t_max(1.1±0.8) h; AUC_last (34±11) μg·h·L^-1; AUC_inf (39±13) μg·h·L^-1。结论: 单次5~15 mg 给药后,伊伐布雷定的体内过程符合一级线性动力学过程,代谢产物S-18982的体内过程呈非线性;连续多次 5 mg 给药后,母药和代谢产物的血药浓度第5天可达稳态,母药在体内无蓄积,代谢产物存在蓄积现象。     

Eutectoid transformations accompanied by ordering

Eutectoid transformations accompanied by ordering, unlike ordinary ones, proceed through non-pearlitic modes of transformations. Eutectoid invariants are classified into two categories in binary systems. The eutectoid invariant of A3()→D0₁₉(₂) + L1₀(γ) in the Ti-Al binary system belongs to the first category, in which one product phase has an ordered structure of a parent phase. Its transformation product exhibits a γ/₂ lamellar structure consisting of nearly perfectly aligned alternate lamellae of γ and ₂, which is formed by precipitation of γ plates in either or ₂ matrix with the Blackburn orientation relationship. The eutectoid invariant of A1(γ)→D0₂₂(γ″) + L1₂(γ′) in the Ni₃V-Ni₃Al pseudo-binary system is an example of the second category, in which both product phases have different ordered structures of a parent phase. The transformation of a 75Ni-18V-7Al alloy results in a ‘checkerboard’ pattern consisting of a periodic array of columns of γ′ and two γ″ orientation variants, which are formed by phase separation simultaneous with ordering.     

Interfacial Features of Stainless Steel/Titanium Alloy Multi-metal Fabricated by Laser Additive Manufacturing

Laser additive manufacturing (LAM) is promising for fabricating multi-metallic component, but the mechanism of microstructural evolution at the interface of two metals is still needed to research further. In this study, a 316L stainless steel/Ti6Al4V alloy multi-metal was fabricated by LAM, and the mechanism of intermetallic phase transformation was deeply investigated. Results show that a strong reaction zone (SRZ) can be induced at the interface of the multi-metal. The phase constituents at the SRZ vary from χ (Ti₅Fe₁₇Cr₅) + Fe₂Ti + α′-Ti + β-Ti or FeTi to Fe₂Ti + χ when the laser power is increased. When the scanning speed is further decreased, the thickness of the SRZ is significantly increased, and α′-Ti phase is also formed at this region besides Fe₂Ti and χ phases. Moreover, the micro-hardness at the SRZ is increased, caused by the intermetallic phase transformation and elemental interdiffusion at the interface.     

利巴韦林含片的人体药动学及生物等效性研究

目的:建立人血浆中利巴韦林的HPLC-MS分析方法, 用以测定18 名健康男性受试者舌下含服不同厂家的利巴韦林含片后的血药浓度, 估算受试制剂和参比制剂的药动学参数, 评价两种制剂是否生物等效。方法:采用双周期随机交叉试验设计。分别给予18 名男性健康受试者试验制剂或参比制剂80 mg, 采集静脉血样, 血浆样品去蛋白后用HPLC/MS/MS 法检测药物浓度。计算药动学参数, 判定两制剂是否生物等效。结果:测定利巴韦林的线性范围为2 ~ 500 ng/mL (r² 为0.9944), 平均回收率>90 %, 日内RSD 和日间RSD 均<10 %。测得血浆中两种制剂的利巴韦林的主要药代动力学参数t_max 、C_max 、t _1/2 、AUC_{0 -72} 和AUC_0→∞分别为:(1.1 ±0.5) 、(1.1 ±0.4) h, (249±89) 、(232 ±65) ng/mL, (34 ±11) 、(34 ±11) h,(2828 ±1215) 、(2685 ±1096) ng^。h^。mL^-1, (3600 ±1568) 、(3416 ±1379) ng^。h^。mL^-1 。以AUC_{0 -72} 计算, 利巴韦林含片的相对生物利用度平均为(106±16) %。结论:本方法更简便、准确, 灵敏度得到很大提高。两种制剂的利巴韦林药代动力学参数无统计学差异, 具有生物等效性。     

Heat capacity and phase equilibria in rare earth alloy systems. R-rich R-Al alloys (R=La, Pr and Nd)

Molar heat capacities of the R-Al (R=La, Pr and Nd) R-rich alloys were determined at different temperatures by differential scanning calorimetry both by using the stepwise and the enthalpimetric methods. The results obtained for the molar heat capacity of Pr₃Al, βPr₃Al and Nd₃Al phases have been reported together with the values obtained for liquid La–Al alloys (x_Al=0.25). The characteristic temperatures obtained for the different invariant reaction involved in the R-rich region have been compared with the literature data. The ↔βPr₃Al transformation has been confirmed at 330°C and a value of Δ_trsH+0.09 kJ/mol of atoms obtained for the transformation enthalpy.     

Temperature dependence of the viscoelastic response of In, Sn and In–Sn alloys

The elastic modulus and the internal friction of Sn and the γ-In–Sn phase are measured with a two-component piezoelectric oscillator at 50 kHz in the temperature range from 296 to 390 K. For both materials the viscoelastic responses at strains below 10⁻⁶ are described in terms of a Debye peak characterized by an effective activation enthalpy of 54.8 and 20.4 kJ/mol, for Sn and the γ-In–Sn phase, respectively. Due to their higher damping, the dynamic mechanical responses of In and the eutectic In–Sn were measured with a three-components piezoelectric resonator between 296 and 390 K at 50 kHz. The temperature dependence of the internal friction of the eutectic can be well described in terms of a single relaxation time with an effective activation enthalpy of 38 kJ/mol. Indium is not only amplitude dependent but also exhibits thermal hysteresis.     

电子封装中Cu/Sn/Cu焊点组织演变及温度对IMC立体形貌影响

通过电镀的方法在抛磨好的铜基体沉积4 μm的锡层,并组合成一个Cu/Sn/Cu结构.分别选择240℃、1 N作为钎焊温度和钎焊压力,在不同的钎焊时间下制备焊点,分析了Cu/Sn/Cu焊点组织演变规律.分别制备了不同钎焊温度下（240,270,300℃） Cu₆Sn₅和Cu₃Sn的立体形貌,分析了温度对Cu₆Sn₅和Cu₃Sn立体形貌的影响规律.结果表明,钎焊30 min后Cu₆Sn₅为平面状,随着钎焊时间的增加逐渐转变成扇贝状.在扇贝底部的Cu₃Sn要比扇贝两侧底部的Cu₃Sn厚.增加钎焊时间锡不断被反应,上下两侧Cu₆Sn₅连成一个整体.继续增加钎焊时间Cu₆Sn₅不断转变成为Cu₃Sn.随着钎焊温度的升高Cu₆Sn₅的立体形貌逐渐由多面体状转变成匍匐状,而Cu₃Sn晶粒随着钎焊温度上升不断减小.     

Temperature Effect on Early Oxidation Behavior of NiCoCrAlY Coatings: Microstructure and Phase Transformation

Initial oxidation behavior of NiCoCrAlY coating prepared by arc-ion plating has been studied in air at 900, 1000 and 1100 °C. The results showed that phase transformation from transient θ-Al₂O₃ to α-Al₂O₃ was highly related to the temperature and oxidation time. The oxide scale in the initial stage was mainly composed of θ-Al₂O₃ at 900 °C. Instead, more amount of α-Al₂O₃ emerged out with increasing oxidation temperature. The elemental distribution after oxidation confirmed that faster chromium diffusion to the oxide scale played an important role in the speedy transformation from θ-Al₂O₃ to α-Al₂O₃. Y segregation at scale/coating interface resulted in less cavity formation and hence improved the oxide scale adherence.