SnPb钎料与Au/Ni/Cu焊盘反应过程中Au的分布

采用熔融的共晶锡铅钎料熔滴与Au/Ni/Cu焊盘瞬时接触液固反应形成钎料凸点,随后进行再流焊及老化.对这一过程中的钎料/焊盘界面金属间化合物组织的演化,尤其是Au-Sn化合物的形成及分布进行了研究.结果表明,钎料熔滴与焊盘液固反应形成了Au-Sn界面化合物,铜层未完全反应.在随后的再流焊过程中,界面处的铜层完全消耗掉,镍层与钎料反应形成Ni3Sn4界面组织;针状的AuSn4化合物分布于钎料基体中.老化条件下分布于钎料基体中的AuSn4重新在界面沉积,在Ni3Sn4层上形成(AuxNi1-x)Sn4层.(AuxNi1-x)Sn4在界面的沉积遵循分解扩散机制,并促进富铅相的形成.钎料与焊盘反应过程中Au-Sn化合物的演化及分布直接影响钎料与焊盘的连接强度.     

激光与红外重熔对63Sn37Pb/焊盘界面微观组织的影响

研究了塑料球栅阵列 (PBGA)钎料球激光重熔以及红外二次重熔过程中 6 3Sn37Pb共晶钎料与Au/Ni/Cu焊盘之间界面反应。结果表明 :钎料凸点 /焊盘界面处金属间化合物的形貌和数量与激光输入能量密切相关。随着激光输入能量的增大 ,Au完全溶解到钎料中 ,界面处连续分布的Au Sn化合物层全部转变为针状AuSn4 相 ,部分针状AuSn4 从界面处折断并落入钎料中 ,最后变为细小的颗粒状弥散分布在钎料内部。红外二次重熔后焊点界面处的针状AuSn4 溶解到钎料中 ,钎料组织由原来的粒状结晶结构变为层片状结晶结构 ,焊点界面处出现了不同形态的粗大富Pb相     

激光重熔PBGA钎料球与Au/Ni/Cu焊盘的界面反应

研究了塑料球栅阵列（PBGA）钎料球重熔过程中钎料与Au/Ni/Cu焊接之间的界面反应，结果表明：界面处金属间化合物的生成与激光输入量能密切相关，当激光输入能量较小时，焊盘上的Au没有完全溶解到钎料中，界面处存在一层连续的AuSn2和一些垂直或斜向生长到钎料中的针状AuSn4化合物，增大激光输入能量，Au完全溶解到钎料中，界而处连续的AuSn2化合物层全部转化为针状AuSn4相，有部分AuSn4针从界面处折断并落入钎料中，当激光功率为18W，激光加热时间为400ms时，AuSn4相在界面处消失，以细小颗粒弥散分布在钎料内部。     

钎料熔滴与焊盘界面反应及再重熔时的界面组织演变

采用熔滴直接凸点制作方法,对共晶SnPb及SnAgCu钎料熔滴与Au/Ni/Cu焊盘所形成的凸点/焊盘界面组织进行了研究,并与激光重熔条件下获得的凸点/焊盘界面组织进行了比较,考察了凸点/焊盘界面组织在随后的再重熔过程中的演变.结果表明:钎料熔滴与焊盘在接触过程中形成了Au-Sn化合物,Au层并未完全反应.在随后的再重熔过程中,Au层被完全消耗,全部溶入钎料基体中,Ni层与钎料发生反应.无铅钎料(SnAgCu)和SnPb钎料所形成的界面组织明显不同;再重熔后SnPb钎料/焊盘的界面组织为Ni3Sn1,SnAgCu钎料/焊盘界面组织为(CuxNi1-x)6Sn5.     

交变电磁辐射下SnPb共晶钎料在BGA焊盘上的自发热重熔及界面反应

进行了交变电磁辐射下附Au／Ni镀层BGA焊盘上SnPb共晶钎料球感应自发热重熔形成钎料凸台的实验，并分析了感应自发热重熔以及固态老化对SnPb共晶钎料与Au／Ni镀层焊盘界面反应的影响．研究结果表明，交变电磁辐射一次重熔与红外重熔结果一样使Au镀层完全消失，并在钎料中形成离散的针状AuSn4，但是二次重熔结果由于电磁场作用下液体金属内固态金属颗粒聚集效应作用的结果使AuSn4金属间化合物富集在钎料与焊盘的界面处．固态老化过程中针状AuSn4转化为层状(AuxNi1-x)Sn4并粘着在Ni3Sn4上，抑制Ni3Sn4的长大。     

AuSn钎料及镀层界面金属间化合物的演变

对激光软钎焊下AuSn钎料与Au和Au/Ni金属化镀层界面形成的金属间化合物进行SEM及EDX分析,并讨论激光输入能量对界面金属间化合物演变规律的影响.研究结果表明：在激光加热及快速冷却条件下,Au迅速溶解到界面附近的钎料中,使得成分偏离共晶点,界面处生成稳定的Au5Sn;随着激光功率及加热时间的增加,未完全溶解的Au层变薄,Au5Sn向钎料内部长大.     

AuSn钎料及AuSn/Ni焊点的组织性能研究

分别采用叠轧-合金化法和回流焊技术制备AuSn箔材钎料和AuSn/Ni焊点,用扫描电子显微镜及电子万能试验机研究钎焊时间对AuSn/Ni界面组织及焊点剪切性能的影响。结果表明:采用叠轧-合金化法制备的AuSn钎料的熔点和化学成分都接近Au-20Sn共晶钎料。Ni/AuSn/Ni焊点在330℃钎焊30s时形成良好的层状ζ-(Au,Ni)5Sn+δ-(Au,Ni)Sn共晶组织;钎焊60s时,AuSn/Ni界面产生薄而平直的(Ni,Au)3Sn2金属间化合物(IMC)层和针状(Ni,Au)3Sn2化合物;随着钎焊时间继续延长,(Ni,Au)3Sn2IMC层厚度明显增加,针状(Ni,Au)3Sn2化合物异常长大。同时,随着钎焊时间延长Ni/AuSn/Ni钎焊接头的剪切强度先增加后减小,钎焊90s时的剪切强度达到最高12.49MPa。     

钎焊中Au80Sn20共晶钎料与Ni/Au镀层的界面反应

采用Au80Sn20共晶钎料钎焊4J34可伐合金基板与铝硅基板(50%Si-Al),板材表面均有Ni/Au镀层。通过光学显微镜研究了工艺参数对钎缝宏观形貌的影响。采用扫描电镜、EDS能谱分析和XRD检测研究了钎缝组织成分以及钎料与基板、基板镀层间的元素扩散和界面反应,从而探究异种金属材料钎焊连接机理。结果表明,钎焊时,基板材料表面的Au层完全进入钎料中,暴露出的Ni层与钎料中的Sn形成金属间化合物Ni_3Sn_4,钎料发生共晶反应生成AuSn共晶与Au5Sn棒状枝晶,并析出大量的Au,Au_5Sn包围在Ni_3Sn_4外围,钎料中间层形成AuSn共晶与富Au区。基板元素Fe、Co、Al、Si和钎料元素Au、Sn均无法通过Ni镀层的阻挡相互扩散,唯一能突破Ni镀层在基板和钎料中扩散的是P元素。     

退火工艺对Au-20Sn钎料组织的影响

采用叠轧-合金化法制备Au-20Sn钎料,研究合金化退火工艺对Au-20Sn钎料显微组织的影响。结果表明:Au/Sn界面在叠轧过程中形成AuSn4,AuSn2和AuSn三个金属间化合物(IMC)层。在200℃退火时,IMC层的厚度随退火时间的延长而逐渐增大。当退火时间延长至48 h时,IMC层发生转变,Au-20Sn钎料最终形成由ζ相(含Sn 10%～18.5%,原子分数)和δ(AuSn)相组成的均质合金。在250℃退火时,Au/Sn界面扩散速度增大,退火6 h后Au-20Sn钎料组织完全转变成ζ相+δ(AuSn)相。在270℃退火时,IMC层熔化,反应界面转变成为固-液界面,Au-20Sn钎料组织转变为脆性的(ζ’+δ)共晶组织。综合Au-20Sn钎料的性能和生产要求,得到优先退火工艺为250℃退火6 h。     

SnIn钎料与Au/Ni/Cu钎焊界面金属间化合物的研究

将InSn49钎料与镀Au/Ni的Cu基焊盘在140℃时进行钎焊,采用扫描电镜(SEM)和能谱仪(EDS)分析研究钎料以及钎焊反应生成的金属间化合物(IMC)的成分及形貌结构。研究发现:InSn49合金钎料为两相组织,分别为富In的β相和富Sn的γ相;当钎焊温度为140℃,保温10s后,还有部分未反应完全的镀Au层,反应生成的IMC成分为AuIn_2,AuIn_2呈多面立方体结构,靠近钎料一侧的AuIn2颗粒较为粗大,分布不均匀,靠近镀Au层方向的AuIn_2颗粒较细小,分布较为致密;钎焊完成后,在靠近IMC区域的InSn49钎料存在明显的γ相偏析现象,偏析区域的γ相的厚度约为60μm。     

Structural, mechanical and corrosion properties of TiOxNy/ZrOxNy multilayer coatings

Results on the deposition and characterization of TiO_xN_y/ZrO_xN_y multilayers, with bilayer periods of 20 and 400 nm, are presented. The coatings were deposited on TiNiNb alloy substrates by the pulsed magnetron sputtering method. The elemental composition, hardness, adhesion and corrosion resistance of the coatings were analyzed.As resulted from the XPS analysis, the individual layers consisted of a mixture of titanium or zirconium oxynitrides and corresponding oxides. X-ray analysis revealed that the coatings were amorphous. Only slight differences between the microhardness and adhesion values of the coatings with small and large bilayer period Λ were found. The experiments also showed that the multilayered coatings improved the corrosion resistance of the uncoated alloy and reduced the amount of ion release in artificial body fluids.     

Hydrothermal synthesis of superconductors Ba1−xKxBiO3 and double perovskites Ba1−xKxBi1−yNayO3

Superconductors Ba_1−xK_xBiO₃ and body-centered double perovskites Ba_1−xK_xBi_1−yNa_yO₃ have been selectively synthesized by a facile hydrothermal route. The appropriate ratio and adding sequence of initial reagents, alkalinity, reaction temperature and time are the critical factors that influence the crystal growth of the compounds. The purity and homogeneity of the crystals were detected by the ICP, SEM, EDX and TEM studies. Magnetic measurements show that the superconducting transition temperatures T_C of Ba_1−xK_xBiO₃ decrease from 22 K (for x = 0.35) to 8 K (for x = 0.55) with increasing the K doping level.     

MOCVD growth and characterizations of BxAl1−xAs and BxAl1−x−yInyAs alloys

Zinc-blende B_xAl_1−xAs and B_xAl_1−x−yIn_yAs alloys have been grown on exactly oriented (0 0 1)GaAs substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). The influence of susceptor coating, growth temperature and gas-phase boron mole fraction on boron incorporation into AlAs has been comprehensively investigated. It has been found that boron incorporation into AlAs could be enhanced and the optimal growth temperature range of B_xAl_1−xAs alloys changed from 580 °C to 610 °C when SiC-coated graphite susceptors were replaced by the non-coated ones. In this study, the maximum boron composition x of 2.8% was achieved for the pseudomorphically strained B_xAl_1−xAs alloys. AFM measurements show that RMS roughness of B_xAl_1−xAs alloys increased sharply with the increase of gas-phase boron mole fraction. Raman spectra of B_xAl_1−xAs alloys show a linear increase of the BAs shift with boron composition x. Based on BAlAs deposition, bulk B_xAl_1−x−yIn_yAs (x = 1.9%) quaternary alloy was grown lattice-matched to GaAs successfully. Moreover, 10-period BAlAs/GaAs and BAlInAs/GaAs MQW heterostructures were also demonstrated.     

生物医用NiTi形状记忆合金腐蚀研究进展

镍钛形状记忆合金(NiTi-SMA)具有较好的耐腐蚀和机械性能,在口腔和临床医学中有着大量而广泛的应用。NiTi-SMA腐蚀后释放Ni²⁺会引发细胞毒性和过敏反应,进一步提高NiTi-SMA的耐蚀性是目前生物医学材料领域发展的核心之一。本文对近年来国内外有关口腔医学和临床医学中常用NiTi-SMA的腐蚀研究现状进行了总结,同时也对NiTi-SMA增材制造及表面改性技术进行了评述,以期为开发高性能抗腐蚀生物医用NiTi-SMA提供一定的指导意义。     

Li掺杂Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3高熵陶瓷的制备及介电性能研究

近年来,在高熵合金基础上发展起来的高熵陶瓷逐渐引起了研究者的广泛关注,其出现为开发高性能的无机非金属材料提供了新的设计思路。本文采用固相法制备了BaMO3基钙钛矿型高熵陶瓷Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3 (x = 0, 2.3%, 5.3%, 8.3%, 11.3%),并研究了Li含量对高熵陶瓷物相结构、微观形貌及介电性能的影响。结果表明,Li含量对陶瓷结构的影响不大,陶瓷均保持立方钙钛矿结构,且无杂相产生;陶瓷的晶粒尺寸相对较均匀。当x = 0时,即B位七元等摩尔比Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li1/7)O3高熵陶瓷,其介电常数达到了最大值2920 (@100 Hz),相较于已报道的不掺Li的六元高熵钙钛矿陶瓷Ba(Ti1/6Sn1/6Zr1/6Hf1/6Nb1/6Ga1/6)O3提升了近50倍。     

Magnetic phase diagrams of the TbRh2−xPdxPdxSi2 and TbRu2−xPdxSi2 systems

The a.c. susceptibility and high field magnetization on TbRh_2−xPd_xPd_xSi₂ and TbRu_2−xPd_xSi₂ compounds were investigated up to 140 kOe. The (T,x) magnetic phase diagrams were determined. For both systems, an increase in the Pd content causes a decrease in the Néel temperature and changes the magnetization curves.     

High strength and good ductility of casting Al-Cu alloy modified by PrxOy and LaxOy

A modified Al-Cu alloy with high tensile strength and ductility of about 574.0 MPa and 10.4%, respectively, was obtained by adding multiple rare earth oxides (Pr_xO_y and La_xO_y) as modifier. Compared with the unmodified Al-Cu alloy, the tensile strength and ductility of the modified sample were increased by 24.3% and 42.5%, respectively. The improvement both in the strength and ductility may attribute to the finer crystal grains and dendrites, more homogeneously distributed θ′ phase precipitates and the intermetallic compounds formed at the crystal grain boundaries as well as in the space of the dendrites.     

Si3N4/Ti/Cu/Ni/Cu/Ti/Si3N4二次部分瞬间液相连接强度

采用Ti/Cu／Ni中间层对Si3N4陶瓷进行二次部分瞬间液相(PTLP)连接，研究连接工艺参数对Si3N4／Ti/Cu／Ni连接强度的影响，同时研究了连接强度随试验温度的变化规律。结果表明，在该试验条件下，室温连接强度随着二次连接温度的提高和二次保温时间的延长而提高，改变连接工艺参数对Si3N4／Ti/Cu／Ni二次PTLP连接界面反应层厚度无明显影响；连接强度在试验温度400℃时达到最大，随后随试验温度升高，连接强度降低，但在800℃前，其高温强度具有很好的稳定性。     

Physical properties of Mo6−xRuxTe8 and Mo6Te8−xSx

A series of the Chevrel phases, Mo_6−xRu_xTe₈ and Mo₆Te_8−xS_x (x=0, 1, 2), has been prepared and the various physical properties, such as the elastic modulus, Debye temperature, and electrical resistivity, have been evaluated. The relationships between several properties of the compounds have also been studied. Young’s modulus and Debye temperature of Mo_6−xRu_xTe₈ and Mo₆Te_8−xS_x increase with increasing x value. The relationship between the Vickers hardness and Young’s modulus shows ceramic characteristics for Mo_6−xRu_xTe₈, while they show glass-like characteristics for Mo₆Te_8−xS_x. The electrical resistivities of Mo_6−xRu_xTe₈ and Mo₆Te_8−xS_x increase with increasing x value.     

Thermoelectric properties of Sn1−x−yTiySbxO2 ceramics

Thermoelectric properties of Sn_1−x−yTi_y Sb_xO₂ ceramics were investigated in detail. The addition of Sb into SnO₂ matrix increased the electric conductivity, σ. The increase in the σ value should be caused by the increase in the carrier concentration. The Seebeck coefficients of all the samples were negative, which means that these samples have n-type conduction. The samples of this study have porous structure. The maximum Z value of all the samples measured in this study was 2.4 × 10⁻⁵ K⁻¹.