铜基活性钎料钎焊Al_2O_3/Kovar的接头组织和强度研究

研究开发了Al_2O_3陶瓷与Kovar合金直接钎焊用Cu-Sn-Ti-Ni活性粉末钎料。在真空下采用该钎料钎焊Al_2O_3和Kovar合金,并对接头的微观组织、抗剪强度及断口进行了分析。结果表明,Al_2O_3/钎料界面上生成了厚度约为1μm的反应层,该反应层主要由Cu_3TiO_4和AlTi组成;钎料层主要由Cu(s,s)、NiTi和TiFe_2等组成。Al_2O_3与Kovar在920℃真空条件下焊接性能良好,抗剪强度102.86 MPa,且断裂主要发生在Al_2O_3陶瓷与钎料结合的界面上。     

CuMn基钎料对TZM与Kovar合金的钎焊研究

采用研制的CuMn基钎料对TZM与Kovar合金进行了高频真空钎焊研究。利用DTA、氦质谱捡漏仪、激光共聚焦显微镜、SEM、EDS等分析手段,测试了钎料的熔点、对TZM与Kovar合金润湿性,分析了钎缝的气密性、微观组织形貌、界面组织成分等。结果表明:在965℃时,CuMn基钎料在TZM与Kovar合金样品上的润湿角θ分别为30.77°和12.30°。在最大钎焊感应电流为430 A时,焊料对钎缝铺展均匀,钎缝区域无裂纹、无气泡等缺陷,焊件气密性测试漏气率优于6×10~(-11)Pa·m~3/s。钎缝中间层区域为CuMn基钎料凝固组织,钎料与TZM反应界面区域较窄,与Kovar合金的界面反应区域较宽。钎料中的Mn、Cu元素与Kovar合金中的Fe元素更容易相互扩散迁移发生冶金熔合反应。     

TiC/NiCr金属陶瓷与1Cr13不锈钢的真空钎焊

以CuMnNi和CuMnCo合金为钎料,采用真空钎焊方法实现了TiC/NiCr金属陶瓷与1Cr13不锈钢的牢固连接.研究了钎料类型及钎焊工艺对钎缝接头力学性能与微观结构的影响.结果表明,采用CuMnNi钎料时在1 050 ℃保温30 min的钎焊工艺下获得了最高界面抗剪强度为338 MPa,而采用CuMnCo钎料时在1 050 ℃保温60 min的钎焊工艺下获得了最高界面抗剪强度为274 MPa,剪切断口发生在金属陶瓷靠近钎缝侧.良好的界面扩散互溶是获得较高界面连接强度的主要原因.并通过扫描电镜(SEM)、X射线衍射分析等方法对钎焊接头微观组织、剪切断口进行了观察和分析.     

Al_2O_3陶瓷与TiAl合金真空钎焊接头界面组织及性能

采用AgCuTi活性钎料实现了Al_2O_3陶瓷与TiAl合金的钎焊连接,研究了钎焊接头的界面结构及其形成机制,并且分析了不同钎焊参数对接头界面组织和接头力学性能的影响规律。结果表明:Al_2O_3陶瓷与TiAl合金钎焊接头的典型界面组织为:Al_2O_3/Ti_3(Cu,Al)_3O/Ag(s.s)+Cu(s.s)+AlCu_2Ti/AlCu_2Ti+AlCuTi/TiAl。钎焊过程中,TiAl基体向液态钎料中的溶解量决定了钎焊接头界面组织的形成及其演化。随着钎焊温度的升高和保温时间的延长,Al_2O_3陶瓷侧的Ti_3(Cu,Al)_3O反应层增厚,钎缝中弥散分布的团块状AlCu_2Ti化合物逐渐聚集长大。陶瓷侧界面反应层的厚度和钎缝中AlCu_2Ti化合物的形态及分布共同决定着接头的抗剪强度。当钎焊温度为880℃,保温10 min时,接头的抗剪强度最大,达到94 MPa,此时接头的断裂形式呈现沿Al_2O_3陶瓷基体和界面反应层的复合断裂模式。     

Super-Ni/NiCr叠层材料Ni-Cr-Si-B高温钎焊接头的组织特征及抗剪强度

采用Ni-Cr-Si-B高温钎料对Super-Ni/NiCr叠层复合材料和Cr18-Ni8不锈钢进行真空钎焊,并分析钎焊接头的显微组织及物相组成、显微硬度、抗剪强度及断口形貌.结果表明,钎缝主要由γ-Ni固溶体、Ni₃B、CrB和Ni₃Si组成;钎缝的显微硬度波动较大,γ-Ni基体显微硬度为450 MPa,Ni₃B的显微硬度最高650 MPa.钎焊温度升高至1120℃时,接头的抗剪强度最高可达158 MPa,NiCr基层钎缝区呈脆性断裂,出现撕裂韧窝.钎缝区与Super-Ni复层之间形成Ni₃B界面,Super-Ni复层钎缝区断裂于Ni₃B界面.     

氧化锆陶瓷与Kovar 4J28合金的金基钎焊研究

采用Au-Cu-Pt合金钎料带,对氧化锆陶瓷与Kovar 4J28合金进行了钎焊研究,探讨了钎焊温度和保温时间对接头强度的影响,并分析了氧化锆陶瓷与4J28合金的界面结合情况。结果表明,氧化锆陶瓷与Kovar 4J28合金在1040℃保温20 min焊接,得到的焊接器件能够承受最大的剪切强度为85 MPa;在压力差为60 k Pa时,封接器件不泄漏。     

Al2O3陶瓷/AgCuTi/GH99高温合金的钎焊接头力学性能

采用AgCuTi钎料对Al₂O₃陶瓷与GH99高温合金进行了钎焊连接,研究了工艺参数(连接温度、保温时间)的变化对接头力学性能的影响,并分析了不同参数下接头的断裂位置,结果表明：保温5min时,在不同的连接温度下进行钎焊,随着连接温度的升高,接头的抗剪强度先增后减,在900℃时取得最大值,为127.24MPa,连接温度较低时,主要断裂于Al₂O₃/钎料侧,随着温度的升高,接头TiNi₃反应层增厚,因此还有部分断裂于TiNi₃反应层/钎料界面;在连接温度为900℃时,随着保温时间的延长,接头的抗剪强度逐渐降低,保温时间较短时,主要要断裂于Al₂O₃/钎料界面,保温时间过长,TiNi₃反应层延伸入钎料中部且厚度大大增加,在该反应层中产生微裂纹,造成接头强度大大降低,此时部分断裂于钎料中部及TiNi₃反应层中。     

Al2O3陶瓷Ti+Nb/Mo金属化对其与Kovar合金钎焊连接的组织和力学性能的影响

采用磁控溅射在Al₂O₃陶瓷表面沉积了Ti+Nb/Mo金属层,实现了氧化铝陶瓷的金属化,并通过电镀镍提高了金属化效果.采用AgCu28钎料,实现了金属化Al₂O₃陶瓷与Kovar合金的可靠连接.通过扫描电子显微镜和能谱观察了钎缝的微观组织.结果表明,钎料与母材发生了明显的界面反应.Cu元素扩散进入Kovar合金,同时Ni元素扩散进入钎料的富铜区,从而促进AgCu/Kovar连接界面的形成;金属化层在Al₂O₃/AgCu钎料界面处,起到了关键作用,其中铌可以抑制脆性化合物形成,缓解残余应力.金属化层镀镍后,钎缝中AgCu共晶区明显,且钎缝较宽,对提高镀镍试样的钎焊接头强度有一定作用.     

YG13C硬质合金钎焊工艺研究

采用中频感应钎焊工艺，分别用HSCuZnNi和HL105钎料对42CrMo钢和硬质合金YG13C进行钎焊，分析了钎料、冷却方式对钎缝抗剪强度的影响。结果表明，HSCuZnNi钎料钎缝的抗剪强度比HL105大20％，采用缓慢的冷却方式可提高抗剪强度。     

中间层厚度对复合钎料钎焊接头强度的影响

采用中间层Cu合金厚度不同的3种CT861复合钎料钎焊低碳钢,研究不同钎料钎焊接头的组织和强度。结果表明:中间层Cu合金厚度不同,复合钎料钎焊低碳钢接头抗剪强度不同,抗剪强度随中间层厚度增加而降低。中间层Cu合金厚度为0.075 mm时复合钎料钎焊接头抗剪强度为214 MPa,Cu合金厚度为0.1 mm时复合钎料钎焊接头抗剪强度为170 MPa,Cu合金厚度为0.15 mm时复合钎料钎焊接头抗剪强度为137 MPa。可根据强度需要,选用不同厚度中间层的CT861复合钎料。     

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