不同Ag元素含量Sn-Ag-Cu无铅钎料性能分析

分别研究了Ag元素含量(质量分数,%)为0.3,1.0,2.0,3.0,3.8的Sn-Ag-Cu(SAC)无铅钎料合金的显微结构、熔化行为、力学性能、润湿性和界面金属间化合物(IMC)形貌.结果表明,随着Ag元素含量的增加,钎料内部金属间化合物晶粒越小,晶粒在钎料中的密度越高,晶粒间距越小,金属间化合物产生的弥散强化越明显,钎料的抗拉强度越高,但韧性越低.随Ag元素含量的提高,钎料越接近共晶成分,熔化温度范围越小.Ag元素含量对润湿性影响不明显,SAC0307/Cu焊点界面IMC晶粒比其它钎料细小.     

冷热冲击对无铅钎料可靠性的影响

文中对比了一种新型低银钎料Sn-Ag-Cu-Bi-Ni（SACBN07）与市场上的SAC305,SAC0307两种无铅钎料的抗冷热冲击性能.利用纳米压痕试验等微观测试方法研究时效后界面组织及力学性能的变化.结果表明,SACBN07的抗冷热冲击性能最好,焊点失效后三种材料中裂纹的扩展路径不同,SAC305失效裂纹位于体钎料中,SACBN07钎料断裂位置逐渐由钎料基体转移到金属间化合物（IMC）层中,而SAC0307断裂位于界面IMC中;钎料中Bi,Ni元素的加入有效地抑制了IMC的生长,相同冷热冲击时间,SACBN07钎料中界面IMC厚度最薄;SACBN07体钎料的硬度受冷热冲击影响最小,时效后仅降低了8.6%,而SAC305与SAC0307分别降低了12.5%和28.3%.     

Sn-Ag-Cu无铅球栅阵列焊点塑性表征

通过纳米压痕的方法,采用塑性应变与总应变的比值表征塑性,对SAC305/Cu、SAC0307/Cu和SAC0705Bi Ni/Cu这3种无铅焊点的动态硬度、抗蠕变性能及塑性进行了对比。3种焊点的动态硬度随深度变化趋势相同,随着压入深度的增加而降低。SAC0705Bi Ni/Cu的最终动态硬度最高,压痕深度最小,SAC305/Cu表现出应变硬化现象。3种焊点的抗蠕变能力由大到小依次为SAC0705Bi Ni/Cu、SAC305/Cu、SAC0307/Cu。SAC0705Bi Ni/Cu焊点的塑性与SAC305/Cu焊点的相当。与SAC305和SAC0307两种钎料相比,无铅钎料SAC0705Bi Ni通过Bi和Ni元素的加入,提高钎料的硬度和抗蠕变性能,并且保持较好的塑性。     

Ni和Bi元素对SnAgCu钎焊界面金属化合物生长速率的影响

通过加速温度时效方法研究Ni和Bi元素对低银(含银量小于1%,质量分数)Sn-Ag-Cu(LASAC)钎料界面IMC生长速率的影响。通过与高银钎料SAC305和低银钎料LASAC对比,分析添加Ni和Bi元素后LASAC钎料在高温时效过程中热疲劳抗性的变化情况。结果表明:LASAC/Cu、LASAC-Bi/Cu和SAC305/Cu界面IMC时效后均形成较厚的Cu3Sn层,LASAC-Ni/Cu界面经IMC时效后则形成较薄的(Cu,Ni)3Sn;高银钎料SAC305在180℃时效下IMC生长速率为2.17×10-5μm2/s,与之相比,低Ag钎料LASAC IMC在时效过程中生长速率较高,为3.8×10-5μm2/s;Ni和Bi元素的添加均可降低钎料LASAC/Cu界面IMC的生长速率,其中Bi的改善效果最显著,LASAC-Bi钎料的IMC生长速率为1.92×10-5μm2/s,低于SAC305钎料的IMC生长速率。     

SnAgCu／Cu微焊点界面IMC演变及脆断分析

随着电子产业无铅化进程的推进,Sn-Ag—Cu（SAC）系无铅钎料备受关注。然而目前市场主流SAC钎料Ag含量（质量分数,3％）较高,导致其成本高,焊点的脆性较大,所以开发低银无铅钎料十分必要。文中以新型低银SAC系钎料为研究载体,对低银无铅微焊点界面金属间化合物（IMC）演变行为及微观力学性能进行了研究．     

加载速率对SnAgCu钎焊接头抗剪强度的影响

研究了加载速率对SnAgCu(SAC)无铅钎料钎焊接头抗剪强度和断裂模式的影响,试验钎料的Ag元素含量为1%～3%(质量分数),微拉剪接头的加载速率为0.01～10mm/s.结果表明,当加载速率小于1mm/s时,抗剪强度随加载速率的增大而增大,断裂模式为发生在接头钎料内部的延性断裂.当加载速率增大到10mm/s时,其抗剪强度反而减小,断裂模式为发生在界面金属间化合物层的脆性断裂.另外,在加载速率较低时,抗剪强度随Ag元素含量的增加而增加;但在较高加载速率下,Ag元素含量为2%的钎料接头抗剪强度最低.     

Ag颗粒增强Sn-58Bi无铅钎料力学性能研究

在Sn-58Bi钎料中添加Ag颗粒,制备颗粒增强的低温无铅钎料,研究了钎料焊接头力学性能。本文研究结果表明：Sn-58Bi合金中添加少于1wt％的Ag会均匀分布在基体合金中,提高了合金钎料的拉伸强度。钎料在100℃恒温时效试验中,Bi相的粗化趋势明显低于Sn-58Bi共晶钎料,提高了合金钎料的组织稳定性。钎料的拉剪强度则随着钎料中Ag含量的增加而升高,但量超过1wt％时,拉剪强度又会下降。     

Sn基无铅钎料晶须生长行为的研究

研究了有机-无机笼形硅氧烷齐聚物(POSS)对Sn基无铅钎料晶须生长行为的影响。分别采用纯Sn和Sn3.0Ag0.5Cu(SAC305)作为基体,加入3%(质量分数)的POSS硅三醇制备复合钎料。样品在-45~85℃的高低温循环条件下进行晶须生长加速实验,并观察样品表面及界面显微组织的演变。结果表明,POSS可在加速条件下稳定钎料基体,同时通过提高钎料的强度和硬度,来缓解钎料在热循环应力作用下产生的塑性形变,进而有效抑制2种钎料的晶须生长。     

Bi元素对SAC305钎料合金组织和性能的影响

利用金相显微镜和微型拉伸试验机对SAC305-Bi钎料合金的润湿性、组织和力学性能进行了研究。结果表明:SAC305-Bi钎料合金的润湿性随着Bi元素含量的提高而逐渐提高;当Bi元素含量低于0.5wt%时钎料合金的组织几乎不变化,当Bi元素的含量高于0.5wt%时钎料合金的组织粗化,当Bi元素的含量达到4wt%时形成了一种新的共晶相;SAC305-Bi的抗拉强度随着Bi元素含量的提高而逐渐提高,其延伸长度则逐渐降低。     

颗粒增强Sn-Bi-Ag钎料的研究

以Sn-Bi系合金作为基础,添加Ag元素,研究开发了Sn-58Bi-Ag无铅钎料.对钎料的显微组织、力学性能和恒温时效条件下钎料的组织稳定性进行了研究.研究结果表明,在Sn-58Bi钎料中添加Ag后,可以有效地减弱钎料中Bi的偏析,细化了焊缝的组织,从而提高了钎料的拉剪强度.时效条件下,Sn-Bi-Ag钎料的组织粗化速率与Sn-Bi钎料的组织粗化速率相比明显减小,钎料具有更加优良的组织稳定性.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

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正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis