通过多级深度还原制备Ti6Al4V合金粉体的新工艺

介绍了一种以TiO₂、V₂O₅和Al为原料，Mg和Ca作为还原剂的通过多级深度还原法制备Ti6Al4V合金粉体的新方法。与传统的冶金方法制备Ti6Al4V粉末相比，该方法具有更高的生产效率和更少的环境污染。自蔓延初级还原实验的结果表明，Mg比Ca更适合在此阶段作为还原剂，当使用Mg作为还原剂时可以得到氧含量为6.74%~16.4%（质量分数，下同）的多孔Ti-Al-V-O前驱体。通过进一步的钙热深度还原（1173 K下保持3.5 h）可以得到含氧量为0.24%的Ti6Al4V粉体。     

多级深度还原法制备Ti6Al4V合金粉体

依据变价金属Ti和V的氧化物在还原过程中逐级还原的特性,提出使用金属氧化物(TiO_2, V_2O_5)作为原料的多级深度还原法制备Ti6Al4V合金粉体的新思路。首先计算了TiO_2-V_2O_5-Mg-Ca体系的吉布斯自由能变,结果表明先进行镁热自蔓延反应,后进行钙热深度还原反应制备Ti6Al4V合金粉体在热力学上具备可行性。然后通过实验进行了验证。镁热自蔓延反应产物酸浸后除去MgO可得到氧含量为15.92%的多孔Ti-Al-V-O前驱体。配入金属Ca后进行深度脱氧可得到低氧的Ti6Al4V合金粉体(Al:6.2%, V:3.64%, O:0.24%, Mg:0.01%, Ca含量0.01%,质量分数)。     

多级深度还原法制备Ti6Al4V合金粉体机理的研究

本文对多级深度还原法制备Ti6Al4V合金粉体过程中的镁热自蔓延反应机理进行了探究。使用XRD，SEM，ICP以及激光粒度分析仪对产物进行了表征。结果表明:Al和V元素会固溶进入Ti基体中使其衍射峰向高角度偏移；“预烧结-还原-烧结”和“还原-烧结”两种反应模式是造成产物形貌差异的主要原因；自蔓延产物的体积平均经D[4.3]和体系的燃烧温度正相关；残留的Mg主要以MgTiO3和MgAl2O4等复合物的形式存在。使用金属Ca进行深度还原可以将最终产物中的Mg和O含量分别降低至0.01wt.%和0.24wt.%。     

通过多级深度还原制备Ti6Al4V合金粉体的新工艺（英文）

介绍了一种以TiO_2、V_2O_5和Al为原料,Mg和Ca作为还原剂的通过多级深度还原法制备Ti6Al4V合金粉体的新方法。与传统的冶金方法制备Ti6Al4V粉末相比,该方法具有更高的生产效率和更少的环境污染。自蔓延初级还原实验的结果表明,Mg比Ca更适合在此阶段作为还原剂,当使用Mg作为还原剂时可以得到氧含量为6.74%～16.4%(质量分数,下同)的多孔Ti-Al-V-O前驱体。通过进一步的钙热深度还原(1173 K下保持3.5 h)可以得到含氧量为0.24%的Ti6Al4V粉体。     

钛及钛合金的新型多级深度热还原技术

提出了"多级深度热还原"的理念,即镁/铝热自蔓延-多级深度还原制备钛及钛合金技术,利用该技术成功制备出纯度为99.69%的高纯还原钛粉,氧含量<0.15%的Ti6Al4V合金粉;制备出20 kg级的Ti Al合金铸锭,其Ti/Al原子比为1∶1,氧含量为0. 09%。该研究成果已在山东淄博傅山企业集团推广应用,所建成的200 t/a钛粉生产线于2019年12月全线贯通投产。实践证明,该技术有效解决了传统金属热还原无法彻底还原TiO_2直接制备钛及钛合金的难题,可使钛材生产成本降低30%左右,为钛材低成本清洁制备与应用奠定了工业化基础。     

多级还原制备钛粉的初级还原机制与配镁量作用规律

目前,Kroll法仍是金属钛生产的唯一工业化方法,新开发的电解法和金属热还原法均处于研究阶段。本文针对多级还原制备钛粉进行了初级还原阶段还原机制与配镁量作用规律的研究。通过分析及结果验证,提高配镁量可促进反应进行的动力学,有利于TiO₂还原程度的提升并抑制镁杂质残留,镁在初级还原过程中多以流体形式包裹在二氧化钛颗粒表面进行传质形成多相微球,钛氧化物则受高温作用发生烧结形成孔隙网络结构的产物形貌。在考虑镁的利用率及实际深度还原产物品质的基础上,实验确定化学计量比为最佳配料比。该配比的初级还原产物氧含量可达16.04wt%,比表面积和中位粒度分别为1.76m^₂/g和 34.39μm,制备的钛粉O、Mg含量分别为0.274wt%和0.010wt%。     

FeTiO3-Fe2O3固溶体合成及其碳热还原研究

为明确Fe₂O₃固溶对FeTiO₃还原过程的影响机理,本文基于粉末煅烧法合成(1-x)FeTiO₃?xFe₂O₃固溶体(0≤x≤1),研究了非等温碳热还原条件下固溶体的还原行为,并采用X射线衍射仪(XRD)和扫描电镜-能谱仪(SEM-EDS)对合成固溶体及还原产物进行表征。结果表明,实验合成固溶体质地均匀,纯度较高,且x越大,FeTiO₃晶格畸变程度越大。固溶体开始还原温度和还原速率(还原度α的增大速率)均随着x值的增加而增加。固溶Fe₂O₃能够促进FeTiO₃还原,且在还原过程中存在过渡相Fe₂TiO₄和Fe₃Ti₃O₁₀。固溶体-石墨交界面首先形成浮士体(FeO)、钛铁尖晶石(Fe₂TiO₄)和TiO₂,进一步还原生成金属Fe和Ti₂O₃。非等温碳热还原过程动力学计算分析,得出表观活化能为295.54 kJ/mol。     

电解TiO2中间相的形成与溢出气体间的关系

熔盐电解TiO₂制备金属钛的过程中,钙钛矿是不可避免的中间相,这已得到国内外研究者的公认。本研究借助间断性实验,主要研究了熔盐电解TiO₂制备金属钛过程中,钙钛矿的形成与TiO₂脱氧及阳极产生气体间的关系。研究结果表明,CaCl₂熔盐中电解TiO₂制备金属钛的过程,按其脱氧进程可分为三个主要阶段。第一阶段为 TiO₂脱氧生成钛的低价氧化物,同时O_2-、熔盐Ca₂₊和未脱氧的TiO₂形成CaTiO₃。第二阶段为CaTiO₃脱氧、脱钙及钛低价氧化物继续脱氧为Ti₂O。第三阶段为Ti₂O进一步脱氧为Ti(2% O)。TiO₂脱氧量、熔盐消耗量及形成CaTiO₃量之间的摩尔比为1:1:1, 且钙钛矿形成阶段阳极只有Cl₂放出,钙钛矿形成结束后阳极放出CO₂、CO气体,无Cl₂放出。若以电解TiO₂到含2%氧的Ti[O]所消耗的时间记为100%的话,那么钙钛矿脱氧、脱钙过程约占总时间的38.9%,而钙钛矿形成的时间只占5.6%,其余时间为钛低价氧化物的脱氧过程。因此钙钛矿的形成是该工艺电流效率低的主要原因之一,钛低价氧化物深脱氧速率低是该工艺的主要限制性环节。     

γ-TiAl合金表面Al2O3/Al复合涂层的抗高温熔盐腐蚀性能研究

采用磁控溅射技术于γ-TiAl合金表面制备Al₂O₃/Al复合涂层。在850 °C下、 100 wt.% Na₂SO₄熔盐中观测Al₂O₃/Al复合涂层的高温腐蚀行为。结果表明,Al₂O₃/Al复合涂层具备由Al₂O₃表层、富Al中间层以及互扩散层组成的梯度结构,因而有效地提高了基体γ-TiAl合金的抗高温腐蚀性能。在腐蚀实验后,涂层试样表面相结构为Al₂O₃,TiO₂和TiAl₃。致密的Al₂O₃/Al复合涂层有效地抑制了O_2-,S_-和Na₊对基体γ-TiAl合金的侵蚀。并且,Al₂O₃/Al复合涂层的梯度结构亦使其表现出了优异的抗开裂和抗剥落性能。     

低温镁热还原TiO2制备金属钛粉的热力学研究

本文针对TiO₂镁热还原产品氧含量高的问题进行了热力学研究,计算了反应体系的吉布斯自由能和绝热温度,绘制了反应优势区图,结果表明当反应温度高于1681 K时TiO无法被镁还原。针对这一问题,提出添加稀释剂的思路以实现对还原过程温度的抑制,计算了不同NaCl、MgCl₂添加量和初始温度对反应绝热温度的影响,指出了钛氧化物充分还原的热力学条件。最后分别以NaCl和NaCl-MgCl₂共熔盐作为稀释剂进行了实验研究,实现了钛氧化物的充分还原。     

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