热变形粉末冶金Ti-45Al-7Nb-0.3W合金热处理过程的组织演变

对锻造态的粉末冶金Ti-45Al-7Nb-0.3W(摩尔分数,%)合金进行后续热处理,研究热处理时间和热处理温度对合金组织演变的影响,利用扫描电镜及透射电镜对合金显微组织进行观察。结果表明:在1230~1260℃温度区间热处理可消除锻造态合金的少量β相。在该温度区间进行等时热处理时,随着热处理温度的升高,α晶粒和γ晶粒迅速长大,γ相体积分数急剧减小,且α晶粒趋于等轴化。合金在1260℃进行等温热处理时,热处理时间由0.5 h延长至6 h,α晶粒和γ晶粒迅速长大,γ相体积分数降低,继续延长热处理时间,显微组织没有明显的变化。通过计算可知,1260℃下α晶粒尺寸的极限值约为0.54 Dγ/Vγ(Dγ为γ晶粒尺寸;Vγ为γ晶粒体积分数)。     

锻造TiAl在热处理时晶粒长大的动力学分析

研究了锻造Ｔｉ－４８Ａｌ－２Ｃｒ（ａｔ％）在１１８０℃热自理音的组织演变,分析在不同温度等温热处理进晶粒长魇 动力学,在Ｔａ以上等温热处理时,昌粒长大迅速,其晶粒长大因子为２．４。在Ｔａ以下等温热处理进,当热处理由１０ｍｉｎ不断延长到４ｈ时,ｒ晶粒尺寸变化较小,α晶粒不断长大。热处理温度越高,晶粒长大越快在１１８０℃,１２２０℃,１２６０℃和１３００℃热处理进晶粒长大因子分别为２．９,２．８．２．     

高温钛合金Ti-60与IMI834的β晶粒长大规律

研究了两种高温钛合金Ti-60和IMI834在不同加热温度和不同保温时间下的β晶粒长大规律.结果表明,在β相区加热时,Ti-60钛合金晶粒尺寸较小,且随加热温度和保温时间的不同变化不大,这主要是由于晶界上富Nd稀土相的存在阻碍了晶粒的长大,而IMI834钛合金的晶粒尺寸随保温时间的增加明显长大.晶粒长大动力学表明,在(Tβ 20 ℃)保温时,两种钛合金β晶粒等温长大曲线近似于抛物线规律,晶粒生长指数n均小于1/2.此外,在加热温度(Tβ～Tβ 40 ℃)范围内、等温时间为10 min时,计算并讨论了Ti-60和IMI834合金的晶粒长大激活能.     

Inconel 718合金方坯粗轧加热过程晶粒长大模型

以Inconel 718合金锻坯为研究对象,在1173—1423 K的温度范围内,研究了加热温度和时间对Inconel 718合金锻坯晶粒尺寸变化的影响,推导并验证了具有普适意义的适合Inconel 718合金锻坯粗轧加热过程的晶粒长大模型.研究结果表明:随加热时间的延长,在1173 K加热时,晶粒尺寸变化不显著;1173—1323 K加热时,晶粒尺寸呈线性长大;高于1323 K加热时,晶粒尺寸呈抛物线性长大.所建立的Inconel 718合金的晶粒长大模型适用于等温条件和非等温条件下晶粒尺寸演变的计算.     

AZ31镁合金等温条件下晶粒长大模型

研究加热温度150~450℃和保温时间对AZ31镁合金晶粒尺寸变化的影响。结果表明:当加热温度一定时,晶粒尺寸随保温时间延长而增加;保温时间一定时,当加热温度在150~250℃范围时,晶粒尺寸随温度升高呈现先增加后减小的趋势。当加热温度大于250℃时,晶粒尺寸随加热温度升高而逐渐增大。基于250~450℃时的实验数据,确定了AZ31镁合金晶粒长大激活能,构建了在等温条件下的AZ31镁合金晶粒长大模型。本文构建的模型计算结果与实验结果吻合较好.     

含Nb高碳钢的奥氏体晶粒长大模型

通过热处理试验和组织观察,研究了在1123~1523 K内加热温度和时间对含Nb高碳钢奥氏体晶粒尺寸变化的影响,分析了奥氏体化过程Nb的析出状态,并推导了含Nb高碳钢等温加热过程的奥氏体晶粒长大模型。结果表明:随着加热时间的延长,在低温区(1123~1423 K)加热时,晶粒长大速率较慢;在高温区(1423~1523 K)加热时,晶粒发生快速长大。所建立的模型适合奥氏体化过程晶粒尺寸演变的计算。     

半固态等温处理对AM60B镁合金组织的影响

研究了半固态等温处理工艺对金属型AM60B的组织和初生相尺寸及形态的影响.结果表明,在半固态等温热处理过程中,网状分布的共晶组织先发生熔化;随着等温时间的延长,α相发生熔化分离;等温时间过长时,球状颗粒有长大、合并的趋势,等温温度越高,晶粒间的合并现象越严重.结果表明,在595 ℃时保温60～75 min可以获得较好的球状非枝晶组织;经过两步法短时的高温保温,非枝晶转变进程加快,可以得到较细小均匀的非枝晶组织.     

热处理对C-276合金无缝管晶粒长大行为的影响

研究了不同的热处理工艺对C-276合金冷轧无缝管晶粒长大行为的影响。结果表明:在同一保温时间下,随热处理温度的升高,C-276合金的晶粒尺寸逐渐增大,且不同保温时间下的晶粒长大趋势相同。当热处理温度为1040～1080 ℃时,晶粒长大较快;在1080～1160 ℃时放缓;在1160～1200 ℃时又加快。在1040～1200 ℃下保温10 min后C-276合金的晶界迁移表观激活能为313.77 kJ/mol。当热处理温度为1040～1080 ℃时,随保温时间的延长晶粒长大较为缓慢;温度为1120～1160 ℃时,当保温时间在10 min内,晶粒长大较快,当保温时间大于10 min后晶粒长大减慢;温度升高到1200 ℃时,随保温时间的延长晶粒长大趋势较为平缓。热处理温度在1040～1200 ℃范围内,随温度的升高,C-276合金的晶粒长大动力学时间指数η先增大后减小。     

纳米Co78Ni22合金组织演变的原位高温X射线分析

采用高温X射线原位分析法研究了喷射电沉积制备的晶粒尺寸5.1 nm的Co78Ni22合金连续加热及等温条件下组织转变.结果表明:在连续加热条件下,随着加热温度升高,晶粒尺寸经历由低温缓慢长大到中温异常长大再到高温正常长大过程,同时ε相向α相转变.在等温条件下,随等温时间的延长,ε相向α相转变且转变的温度降低,随等温温度的升高,这种转变加快,晶粒尺寸也会发生明显的长大.Co78Ni22合金加热过程中的异常晶粒长大与ε相向α相转变有关.     

RAP法制备AlSi7Mg合金半固态坯料研究

采用DSC测试、热镦粗实验、半固态等温处理实验、金相显微镜观察以及Image Pro Plus图像处理软件,研究了等温压缩温度、压缩量和半固态等温处理的温度、保温时间对再结晶重熔(RAP)法制备AlSi7Mg铝合金半固态坯料微观组织的影响.结果表明:等温压缩过程中温度对半固态坯料微观组织的影响不明显,而等温压缩变形量的增大有利于细化半固态坯料微观组织,最优热镦粗参数为温度240℃,变形量40％;半固态等温处理过程中,随保温温度升高,微观组织固相晶粒的尺寸逐渐增大,而随着保温时间延长,半固态组织中固相颗粒的尺寸先缓慢长大再迅速长大然后趋于不变,固相颗粒的圆整度变化较为复杂.通过RAP法制备的AlSi7Mg铝合金半固态坯料平均晶粒尺寸为64～117μm,形状因子为0.76～0.89.低于599℃时,半固态的平均晶粒尺寸的立方粗化线性关系不明显,影响晶粒粗化的机制主要有Ostwald熟化、合并长大、再结晶和熔化;在599℃时,晶粒尺寸的立方粗化线性关系较为明显,此时Ostwald熟化为晶粒粗化的主导机制.     

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