倾斜管制备半固态浆料工艺研究

利用自主开发的倾斜管制浆工艺制备了A356合金半固态浆料。研究了倾斜管制浆主要工艺参数对半固态浆料非枝晶组织的形成与演变规律的影响，同时利用倾斜管制备了圆形铸锭并研究了铸锭不同部位的显微组织。结果表明，倾斜管制备半固态坯料过程中，倾斜角度一般应控制在40^o～60^o，理想浇注温度在620～660℃。在倾斜管通水冷却条件下，对应不同的浇注温度应用不同的斜管长度，可以获得较为理想的显微组织。在一定的浇注长度范围内，低温浇注更有利于获得近球状晶。铸锭组织逐渐由树枝晶向细小的近球晶演变。     

倾斜板制备半固态7A09合金坯料的研究

以浇注温度、倾斜板预热温度、倾斜角度为研究因素,进行了倾斜板法制备7A09合金半固态坯料的正交实验。结果表明,浇注温度660℃,倾斜板预热温度150℃,倾斜板倾斜角度60°是较为理想的工艺参数;浇注温度是晶粒细化最主要的影响因素;控制合适的工艺参数可获得细小、均匀的初生相颗粒。     

铝合金半固态成形晶粒超声细化试验研究

设计了倾斜板—超声凝固复合处理工艺试验方案,研究了三种工艺参数对半固态组织的影响.运用正交试验法对实验方案进行了优化,获得了制备高性能的超细晶半固态材料的成形工艺:浇注温度为685℃、铸型预热温度为30℃、倾斜板预热温度为150℃.该工艺制备的试样组织与性能最佳.     

斜管法流变制浆工艺初探

采用斜管法流变制浆工艺铸造ZL101合金,获得了金属半固态加工要求的细小、近球状的"非枝晶"组织,考查了斜管、浇注温度和冷却速度等因素对组织形成过程的影响.结果表明,斜管在该工艺中起到了增加形核的作用;采用低温浇注有利于形核,但浇注温度又不能太低,浇注温度为635 ℃时的效果最佳;冷却速度太快太慢都难以得到合适的微观组织,结晶器的预热温度为560 ℃时效果最佳.要想得到细小、近球状的"非枝晶"组织,必须有一个合适的冷却规范.     

转动输送管制备半固态ZL101合金浆料

采用转动输送管方法制备了半固态ZL101合金浆料,并对不同工艺参数条件下的合金微观组织形成和演化过程进行了研究.试验结果表明,控制浇注温度(640 ℃)、输送管转速(232 r/min)、结晶器冷却强度(结晶器预热470 ℃)等工艺参数,能得到圆整的半固态显微结构,适当的浇注温度和输送管转速可以提高熔融态合金的有效形核数目,降低结晶器冷却强度有利于初生α相呈近球形生长.     

倾斜板浇注ZA25锌合金的显微组织

采用自制的V型槽倾斜板,通过控制倾斜板长度及倾斜角度,在650℃下浇注了ZA25(含铝为25 wt%)合金铸件。研究了浇注合金的显微组织。结果表明,浇注温度越接近于半固态区域温度、倾斜板长度越长及倾斜角度越小时合金组织越趋近于球状。对倾斜浇注试样进行固溶处理后,发现在440℃固溶处理的ZA25合金组织为近球形,并且晶粒内含有液相。在280℃和230℃的固溶处理仅使铸件枝晶组织粗化,没有改变枝晶组织特征。而普通浇注下ZA25合金的显微组织粗大、呈枝晶状。     

汽车用AZ80合金的挤压铸造工艺及组织性能研究

对汽车用AZ80合金进行挤压铸造,研究浇注温度、挤压压力、模具预热温度和保压时间对AZ80合金组织和力学性能的影响,并分析其作用机理。结果表明,AZ80合金的适宜挤压铸造工艺为:浇注温度700℃、挤压压力90MPa、模具预热温度为250℃、保压时间为25 s,在此工艺下的AZ80合金可以取得较好的强度和塑性结合;AZ80合金力学性能的提高,主要与挤压工艺参数调控合金晶粒大小和显微缺陷有关。     

压力下凝固工艺参数对6061铝合金组织与力学性能影响

采用压力下凝固成型工艺制备6061铝合金,利用正交试验研究了浇注温度、比压、保压时间和模具预热温度等工艺参数对合金力学性能的影响。结果表明,工艺参数对合金力学性能影响权重不同,对抗拉强度的影响权重为:比压模具预热温度浇注温度保压时间,即比压对抗拉强度的影响最大,保压时间对抗拉强度的影响最小;各因素对伸长率的影响权重为:浇注温度模具预热温度保压时间比压,即浇注温度对伸长率的影响最大,比压对伸长率的影响最小。当浇注温度720℃、比压150 MPa、保压时间25 s、模具预热温度150℃时,铸件力学性能最佳,此时抗拉强度为181.7 MPa,伸长率为15.4%。     

7A04合金半固态模锻工艺的实验研究

以两种状态的7A04合金为例,简要分析了二次加热工艺参数、模具预热温度等工艺参数对半固态模锻成形的影响,并重点研究了半固态模锻前后的显微组织变化及不同加热温度下的力学性能.结果表明:半固态模锻件的显微组织与合金的初始状态及其二次加热后的半固态组织密切相关;在同样变形条件下,经半固态模锻后,挤压后冷变形态合金的力学性能好于挤压态合金,其最佳变形温度分别为600℃和605℃.     

倾斜管制备A356半固态浆料工艺参数对组织的影响

利用倾斜管技术制备了A356铝合金半固态浆料,通过改变浇注温度、输送管转速和倾角、结晶器预热温度等工艺参数,观察了半固态浆料的组织变化,研究分析了各种工艺参数对A356半固态浆料的影响规律,获得了理想的微观组织。     

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