机械合金化过程中Fe50Al50二元系的结构演变

利用高能球磨和后续热处理技术制备纳米晶Fe50Al50(摩尔分数,%)合金粉体.采用X射线衍射、透射电镜和扫描电镜对元素混合粉在机械合金化过程中的结构演变及热处理对合金化粉体结构的影响等进行分析,讨论其机械合金化合成机制.结果表明:球磨过程中Al向Fe中扩散,形成Fe(Al)固溶体.机械合金化合成Fe(Al)遵循连续扩散混合机制;球磨30 h后,粉体主要由纳米晶Fe(Al)构成,晶粒尺寸5.65 nm;热处理导致Fe(Al)纳米晶粉体有序度提高,转变为有序的B2型FeAl金属间化合物,粉体的晶粒尺寸增大,但仍在纳米尺度范围.     

机械合金化过程中Fe50Als50二元系的结构演变

利用高能球磨和后续热处理技术制备纳米晶Fe5A150（摩尔分数，％）合金粉体。采用X射线衍射、透射电镜和扫描电镜对元素混合粉在机械合金化过程中的结构演变及热处理对合金化粉体结构的影响等进行分析，讨论其机械合金化合成机制。结果表明：球磨过程中Al向Fe中扩散，形成Fe（A1）固溶体。机械合金化合成Fe（Al）遵循连续扩散混合机制；球磨30h后，粉体主要由纳米晶Fe（A1）构成，晶粒尺寸5．65nm；热处理导致Fe（A1）纳米晶粉体有序度提高，转变为有序的B2型FeAl金属间化合物，粉体的晶粒尺寸增大，但仍在纳米尺度范围。     

机械合金化过程中Fe-Al合金粉末的组织演变

将纯Fe粉和Al粉按原子比Fe∶Al=60∶40混合后,在行星式高能球磨机中进行机械合金化,采用X射线衍射仪、扫描电镜、透射电镜和硬度仪研究球磨过程中Fe-Al合金粉末相结构、晶粒尺寸、表面形貌、截面形貌和硬度的演变规律。结果发现,球磨24 h后,Al原子全部固溶于Fe晶格中,形成Fe(Al)过饱和固溶体,随着球磨时间的增加,晶粒尺寸呈现先快后慢的减小趋势,球磨36 h后合金粉末的晶粒尺寸小于100 nm。粉末内部组织为层状结构,且随着球磨时间延长层片厚度不断减小,球磨36 h后层状结构全部消失,获得组织均匀的纳米晶Fe-Al合金粉末。随着球磨时间延长,Fe-Al合金粉末的硬度不断增加,球磨36 h后合金粉末的硬度约为405 HV0. 025。球磨Fe(Al)固溶体合金粉末在500℃热处理转变为有序Fe Al金属间化合物。     

冷喷涂制备纳米结构FeAl金属间化合物涂层

利用机械合金化制备纳米结构FeAl固溶体合金粉末,采用冷喷涂沉积Fe(Al)固溶体合金涂层并结合后热处理原位反应制备了纳米结构FeAl金属间化合物涂层。通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)等研究了机械合金化Fe(Al)固溶体合金粉末、喷涂态Fe(Al)合金及热处理后FeAl金属间化合物涂层的组织结构特征。结果表明,球磨Fe(Al)合金粉末具有精细的层状结构,喷涂态Fe(Al)合金涂层具有不同于传统热喷涂涂层的独特层状结构,保留了与原始粉末类似的纳米结构;在500℃热处理后涂层中Fe(Al)固溶体转变为FeAl金属间化合物,其晶粒尺寸约为30 nm。     

机械合金化及真空热压制备纳米晶Fe3Al的组织及性能

采用机械合金化(MA)及热压烧结工艺制备纳米晶Fe3Al块体材料。采用X射线衍射、透射电镜、扫描电镜等对MA粉体及热压块体的相及显微组织进行分析,并对热压块体的力学性能及断口形貌进行了测试分析。结果表明:Fe72Al28混合粉在球磨过程中,Al逐渐溶入Fe中,形成Fe(Al)过饱和固溶体,纳米晶粉体的结构有序度较低。在1200℃,保温1h下真空热压烧结,Fe(Al)转变为有序的DO3-Fe3Al,同时发生晶粒长大。Fe3Al块体晶粒尺寸为40.1nm,相对密度大于96%,维氏硬度626.8 HV,三点弯曲强度985MPa;弯曲断口为脆性断口,但也呈现出一定韧性断裂特征。     

WC/FeAl金属间化合物基金属陶瓷涂层的冷喷涂制备

采用WC/Fe/Al混合粉末,通过机械合金化制备40v0l％ WC/Fe(Al)固溶体复合粉末,利用冷喷涂沉积涂层并结合热处理原位反应制备了WC/FeAl金属间化合物基金属陶瓷涂层.研究了球磨时间对复合粉末相结构、晶粒尺寸及组织结构的影响,并分析了冷喷涂WC/FeAl金属间化合物基金属陶瓷涂层的组织和显微硬度.结果表明,机械合金化可获得WC陶瓷颗粒呈微/纳米多尺度分布的WC/Fe(Al)金属陶瓷复合粉末,球磨36 h的复合粉末基体相平均晶粒尺寸约为90 nm,冷喷复合涂层组织致密、多尺度WC颗粒在基体中均匀弥散分布,涂层显微硬度约为1060 HV0.3,涂层在650℃热处理后发生Fe(Al)固溶体向FeAl金属间化合物的原位转变,制备出了WC/FeAl金属间化合物基金属陶瓷涂层.     

原位TiB2/Fe3Al基纳米复合材料的合成及其晶粒生长动力学(Ⅱ)——热处理过程中机械合金化Fe-Al-Ti-B四元粉体的结构演变与晶粒生长动力学

研究了机械合金化合成的Fe-Al-Ti-B四元粉体在800-1100℃等温热处理过程中的结构演变及晶粒生长动力学,讨论了晶粒生长机制。研究表明,采用机械合金化加后续热处理工艺可以合成原位TiB2/Fe3Al基纳米复合材料粉体。球磨80h的Fe-Al-Ti-B四元粉体在热处理过程中Fe(Al,Ti,B)分解形成纳米晶DO3-Fe3Al及TiB2两个组成相。随热处理温度的升高,Fe3Al晶粒生长由主要受晶界扩散控制过渡到主要受晶格扩散控制。在热处理过程中,Fe3Al晶粒生长的动力学方程为:K=1.5×10-5exp(-578.7×103/RT),晶粒生长受到明显的抑制,原位TiB2/Fe3Al基纳米复合材料粉体的热稳定性高。     

3Fe/Al混合粉末的高能球磨及环境介质的相互作用

利用Fritsch Pulversitte 5型行星式球磨机、扫描电子显微镜、X射线光电子能谱仪和X射线衍射仪研究了3Fe/Al元素混合粉末的机械球磨过程以及球磨过程中混合粉末与环境介质的相互作用.研究证实,球磨过程中存在颗粒断裂、冷焊机制,球磨20h产物为α-Fe(Al)固溶体,其表面生成一层由Fe2O3和Al2O3组成的氧化膜.     

MA法制备Fe83Nb7B9Cu1纳米晶粉末及其热稳定性

利用高能球磨法在Fe Nb B Cu体系中获得纳米晶粉末 ,研究了机械球磨过程中产物的组织结构、α Fe相平均晶粒尺寸及其热稳定性。结果表明 :采用Fe 2 0B中间合金粉末代替B粉并未明显影响机械合金化动力学过程 ;球磨至 5h时 ,即可获得平均晶粒尺寸约 18nm的α Fe单相过饱和固溶体 ,其后延长球磨时间 ,晶粒尺寸缓慢减小 ,至 45h后 ,平均晶粒尺寸减小到 9nm。退火处理后的XRD分析表明 ,α Fe过饱和固溶体从 10 0℃开始发生结构弛豫现象 ,738.8℃后则发生了相转变 :α Fe过饱和固溶体→α Fe固溶体 Fe3 B FeB ,在 5 5 0℃以内退火 ,纳米晶粒长大不明显 ,在 770～ 95 0℃范围内退火 ,晶粒开始明显长大 ,但晶粒尺寸仍处于纳米级范围。     

合金化元素对纳米晶铝合金热稳定性的影响

为研究加入Fe和Ti扩散系数有限的元素对纳米晶铝合金热稳定性的影响,制备Al?10%Fe(质量分数)和Al?10%Fe?5%Ti(质量分数)合金。将初始混合粉末在真空下球磨100 h,用高频感应加热烧结系统将球磨后的粉末制备成块体样品。采用X射线衍射仪、维氏显微硬度仪、场发射扫描电子显微镜和透射电子显微镜对球磨后的粉末和烧结后的块体样品进行表征。结果表明,Fe和Ti完全分散在基体中,与Al形成过饱和固溶体。另外,合金元素的加入使合金的硬度和屈服强度分别提高127%和152%。通过高温压缩试验评估合金的热稳定性,结果显示3种合金样品中Al?10%Fe?5%Ti合金的热稳定性最好。Fe和Ti的加入抑制合金的晶粒长大,阻碍第二相如Al13Fe4和Al13Ti的分解、长大,形成稳定的固溶体,从而提高合金的热稳定性。     

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