Cu-Ni扩散偶的扩散溶解层

分别在普通和真空热处理炉中对Cu/Ni镶嵌式扩散偶进行退火热处理,利用扫描电子显微镜和电子探针显微分析仪观察和分析了扩散溶解层的形态和结构,并对其形成机理进行了探讨.结果表明,Cu/Ni扩散偶在950℃、100 h退火处理时,Cu/Ni扩散溶解层主要在Ni块上形成,形状依附于原始界面,并逐渐向Ni块基体延伸,与Ni块没有界面,其结构是以Ni为溶剂、Cu为溶质的间隙固溶体;扩散溶解层的形成机理是Cu原子向Ni块扩散,Ni原子几乎不向Cu丝扩散,Cu丝溶解在Ni块里面.     

Cu-3.2Ni-0.75Si-0.30Zn合金时效过程的动力学分析

通过研究时效过程中电阻率的变化规律 ,分析了Cu 3.2Ni 0 .75Si 0 .30Zn合金的时效析出特性及其动力学过程。结果表明 :低温时效时扩散作用是合金析出过程的主要控制因素 ,时效早期通过调幅分解形成溶质原子的富集区 ,然后在溶质富集区发生失稳有序化 ,最后生成δ Ni2 Si相 ;高温时效时相变驱动力成为主要控制因素 ,由于生成δ Ni2 Si相的驱动力较大 ,所以直接析出δ Ni2 Si相。结合透射电镜研究了合金时效过程中显微组织的变化 ,并得出了合金的时间—温度—转变曲线 (即TTT曲线 )。     

Ni3Al合金蜂窝的制备及微观组织演变规律

目的 研究Ni-Al扩散偶在热扩散过程中的微观组织演变规律,提出Ni3Al合金蜂窝形成的模型.方法 采用电镀技术在易加工的Al蜂窝表面电镀一定厚度的Ni,研究热扩散温度和时间对Ni-Al扩散偶组织结构的影响.采用X射线衍射仪对Ni-Al扩散偶进行物相分析;通过扫描电镜技术对Ni-Al扩散偶截面进行形貌及能谱分析,推测微观组织演变规律.结果 热扩散温度为500℃时,随着热扩散时间的延长,Ni-Al界面处首先出现NiAl3,然后消失,最终形成以Ni2Al3为扩散层主体、NiAl和Ni3Al为过渡层的多层实心结构;热扩散温度为700、1100℃时,Ni-Al扩散偶会分别形成以Ni2Al3、NiAl为内芯,纯Ni为外壳,并以NiAl、Ni3Al薄层过渡的多层中空结构;热扩散温度为1300℃时,随着扩散时间的延长,Al相夹心层从Al、NiAl3、Ni2Al3三相混合结构依次转化为成分均一的单相Ni2Al3和NiAl结构,扩散时间继续延长,Ni层随之耗尽,Ni-Al扩散偶最终形成以γ′-Ni3Al为强化相的Ni-Al合金.结论 Ni-Al固相扩散反应过程中,随热处理温度的提升,Al原子发生了明显的外扩散.Ni-Al液固扩散反应过程中,随热处理时间的延长,Ni原子发生了明显的内扩散.在1300℃热扩散1 h的条件下,能成功制备Ni3Al基合金蜂窝壁.     

碳钢——黄铜中间层——不锈钢液固相扩散结合区组织

用扫描电镜组织观察、能谱微区成分分析、X射线衍射等方法,研究了20钢—液相H62黄铜—304不锈钢液固相扩散结合区的组织.结果表明,通过碳钢、不锈钢与黄铜液相中间层的液固相扩散,低碳钢与不锈钢可以获得良好的冶金结合;在黄铜/不锈钢界面,液相黄铜中Cu,Zn原子沿固相晶界的扩散比较显著,形成网状黄铜包围奥氏体晶粒的组织;在碳钢/黄铜界面,固相向液相中的溶解比较明显,形成岛状富铁相分布于黄铜基体的组织;富铁相中含有较多的Cr和Ni元素,冷至室温仍为奥氏体.     

Fe-B共晶合金在锌液中的腐蚀行为

在500℃的锌液中,对Fe-B共晶合金进行恒温静态腐蚀试验。对其腐蚀动力学和基体/Zn腐蚀界面进行研究,探讨了Fe-B共晶合金在锌液中的腐蚀过程和机理。结果表明,Fe-B共晶合金有比较好的耐锌液腐蚀性能;锌液腐蚀基体的过程是Fe原子和Zn原子相互扩散的过程;扩散导致新相的形成,在热应力和锌液冲击应力以及新相生长的拉应力的作用下,腐蚀层产生裂纹断裂并溶解。腐蚀以此方式反复进行,最终导致合金失效。     

Al-Cu-Zn合金单相凝固过程中的溶质截留

在连续生长模型(CGM)基础上，提出了三元合金溶质截留过程中的驱动自由能和界面温度的计算公式，模拟了Al-Cu—Zn合金单相凝固过程中的溶质截留和界面温度行为,在合金两个不同等深面上，界面移动速度增加时，固相线和液相线向同素异型相界T0曲线靠近；随生长速度的增大，分凝系数急剧增加，在界面速度接近溶质扩散速度时，发生完全溶质截留现象，在速度比较低时的计算表明，合金的平衡分凝系数可在冷却速度小于7．1K／s的凝固过程使用；固相成分一定时，界面沮度随生长速度增加而上升，在溶质扩散速度vD处达到极值后界面温度下降；但液相成分一定时，界面温度随生长速度增加而下降。     

固溶时效对挤压态LAZ941-0.5Y合金组织和力学性能的影响北大核心CSCD

通过OM、XRD、DSC、SEM和力学性能测试等手段,研究了挤压态LAZ941-0.5Y合金经不同的固溶时效处理后的组织和力学性能。结果表明:挤压态合金经固溶处理后,MgLi_2Al和AlLi相完全溶入基体,产生显著的固溶强化效果;50℃时效初期,溶质原子扩散缓慢导致析出动力不足,过饱和基体中析出短棒状的MgLi_2A过渡相,随时效时间延长,MgLi_2A相发生形貌转变,由短棒状变成点状;随时效温度的升高,溶质原子扩散速率加快,MgLi_2A相析出速率变快,部分MgLi_2A亚稳相分解为AlLi相,同时有AlLi从基体中析出。合金的峰值时效在50℃时效0.5 h时发生,随温度的升高很快发生过时效,其主要原因是AlLi软化相的出现。     

固溶时效对挤压态LAZ941-0.5Y合金组织和力学性能的影响

通过OM、XRD、DSC、SEM和力学性能测试等手段,研究了挤压态LAZ941-0.5Y合金经不同的固溶时效处理后的组织和力学性能。结果表明:挤压态合金经固溶处理后,MgLi_2Al和AlLi相完全溶入基体,产生显著的固溶强化效果;50℃时效初期,溶质原子扩散缓慢导致析出动力不足,过饱和基体中析出短棒状的MgLi_2A过渡相,随时效时间延长,MgLi_2A相发生形貌转变,由短棒状变成点状;随时效温度的升高,溶质原子扩散速率加快,MgLi_2A相析出速率变快,部分MgLi_2A亚稳相分解为AlLi相,同时有AlLi从基体中析出。合金的峰值时效在50℃时效0.5 h时发生,随温度的升高很快发生过时效,其主要原因是AlLi软化相的出现。     

常压及高压凝固Al-Mg及Al-Mg-Zn合金中Al相的固溶体结构

采用X射线衍射仪、能谱仪和透射电镜分别对Al-9.6%Mg合金、Al-11Mg-4.5Zn合金和Al-17Zn-1.5Mg合金常压及6 GPa高压凝固后Al相的固溶体结构进行研究。结果表明:6GPa高压凝固后,Al-9.6%Mg合金中Mg在Al相中的固溶度显著增大;在Al-11Mg-4.5Zn合金和Al-17Zn-1.5Mg合金中,Mg、Zn溶质在Al相中的固溶度均增大,但Zn比Mg固溶的比例要大得多。在常压凝固条件下,与纯铝相比,3种合金中Al相的晶格常数均增大。与常压凝固相比,高压凝固Al-9.6Mg合金和Al-11Mg-4.5Zn中Al相晶格常数分别增大了1.178%和0.220%;在Al-17Zn-1.5Mg合金中,Al相晶格常数变化很小。此外,在Al-Mg-Zn合金中,原子半径较大的Mg固溶到Al相中,导致其晶格常数增大,原子半径较小的Zn固溶到Al相中,导致其晶格常数减小,且高压凝固后,溶质的原子半径越小,在Al相中固溶的比例越大。     

Cu-Ni-Si合金时效析出相的长大机制研究

通过测量导电率研究了Cu-3．2Ni-0．75Si-0．30Zn合金在时效过程中的调幅分解行为。结果表明,合金在450℃时效时按照调幅分解机制经历了三个序列:溶质富集区→半共格Ni2Si相→非共格Ni2Si相。即随时效时间的延长,溶质原子富集区出现有序化,形成与基体半共格的强化相(Ni2Si)。继续时效,强化相不断析出与长大, 半共格关系被破坏,最终在表面张力的作用下逐渐球化,导电率和显微硬度上升趋势随之减弱。     

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