Hf和Zr含量对FGH96合金平衡相及PPB的影响

采用材料热力学计算软件Thermo-calc,计算了FGH96合金中的平衡相,并结合显微组织观察、能谱和相分析,探讨Hf、Zr含量对γ’相和碳化物的影响,及对消除PPB的作用。结果表明:Hf和Zr不会导致产生新相,主要影响MC和γ’相的析出行为与成分。Hf和Zr能显著改变MC型碳化物的组分,增加其热力学稳定性和数量,促进MC型碳化物在合金中的均匀分布,抑制MC向M23C6转变;Hf还可以参与形成γ’相,增加其数量。Hf、Zr有助于消除FGH96合金中的原始颗粒边界(PPB)。     

微量元素Hf对镍基粉末高温合金FGH97显微组织的影响

利用SEM和物理化学相分析方法研究了5种Hf含量的FGH97粉末高温合金中γ'相和MC型碳化物形貌、化学组成及含量.结果表明:Hf促进γ'相和MC相析出,改变γ'相和MC相的化学组成,对MC相的尺寸和形貌影响不大,显著影响γ'相的尺寸和形貌,促使γ'相的形态失稳,导致立方状γ'相发生分裂,使γ'相更快地进入稳定的立方状择优形态.在FGH97合金中添加Hf,可通过改变错配度d,从而改变γ'相发生分裂的临界尺寸Dc.建立了Dc与Hf含量w(Hf)的关系式:Dc=315.4+640.2w(Hf)-358.2[w(Hf)]2.随着Hf含量的增加,|d|逐渐变小,Dc增大.γ'相长大到临界尺寸时,γ'相由立方状分裂为八重小立方体状.     

合金元素在镍基粉末高温合金FGH97中强化作用的研究

运用高温合金强化机理,在FGH97合金标准成分的基础上,调整Co、Cr、Mo、W 4种合金化元素的含量,设计了3种合金。结果表明：调整合金元素后,FGH97合金中γ晶格常数获得提高,起到了固溶强化的效果,同时γ/γ′相错配度绝对值的提高增强了共格应变强化的效果;调整合金元素对显微组织、γ′相和碳化物等相的析出没有明显影响,没有增强晶界强化和沉淀强化的效果;固溶强化对强度增量的贡献值最高。     

合金元素对镍基粉末高温合金FGH97的强化作用

运用高温合金强化机理,在FGH97合金标准成分的基础上,调整Co、Cr、Mo、W 4种合金化元素的含量,设计制备了3种合金,以研究合金元素对合金的强化作用。结果表明:调整合金元素含量后,FGH97合金中γ晶格常数获得提高,起到了固溶强化的效果,同时γ/γ′相错配度绝对值的提高增强了共格应变强化的效果;调整合金元素含量对显微组织、γ′相和碳化物等相的析出没有明显影响,没有增强晶界强化和沉淀强化的效果;固溶强化对强度增量的贡献值最高。     

铪对FGH4097合金系热力学平衡析出相和原始颗粒边界的影响

为消除粉末冶金高温合金FGH4097中存在的原始颗粒边界(PPB),采用Thermo-Calc热力学计算软件对FGH4097合金系进行热力学计算,并进行相应的组织观察与能谱分析,重点研究了铪(Hf)在FGH4097合金中的分布规律以及Hf对析出相的影响,特别是分析了Hf对合金中PPB的影响规律。结果表明,FGH4097合金中Hf主要存在于MC、MB2和γ’相中,Hf能促进MC相和γ’相的析出,有效地抑制M6C和M23C6型碳化物的形成。Hf质量分数为0.30%时消除了FGH4097合金中的PPB。     

Hf在FGH4097粉末高温合金中的相间分配行为

采用3DAP、FEG-SEM、TEM以及物理化学相分析方法研究5种Hf含量的FGH4097粉末高温合金中Hf在γ′相、MC型碳化物和γ相中的分配,以及Hf对γ′和MC析出相组成的影响。结果表明:随着合金中Hf含量的增加,进入各相的Hf量增多,Hf进入γ′相的比例基本不变,进入MC型碳化物的比例增大,进入γ相的比例减小,即Hf在γ′相和MC型碳化物的分配比逐渐减小,Hf在γ′相和γ相中的分配比逐渐增大;Hf主要分配在γ′相中,其次分配在MC型碳化物中,Hf在MC型碳化物中的质量浓度大约是Hf在γ′相中的20倍。     

不同三级时效热处理对FGH4097合金显微组织和γ'相演化的影响

采用光学显微镜和扫描电镜研究了 FGH4097粉末高温合金经9种不同三级时效工艺处理后的显微组织和γ'相的演变.结果表明:不同时效制度下FGH4097合金的光学显微组织变化不大,均未见原始粉末颗粒边界组织;不同时效制度对合金的二次γ'相的形态有一定的影响,对三次γ'相的平均尺寸、面积分数、颗粒密度和尺寸分布有明显的影响...     

热处理冷速对FGH97盘件显微组织和蠕变性能的影响

对FGH97粉末高温合金盘件进行热处理,采用光学显微镜、扫描电子显微镜、能谱仪和蠕变试验机研究了不同固溶冷速下合金的显微组织、蠕变性能和蠕变机制。研究表明:随固溶冷速的增加,γ′相尺寸减小,富Ti、Nb、Hf的MC型碳化物由连续析出变为颗粒状弥散析出。在750℃/450 MPa蠕变试验条件下,固溶冷速为94℃/min的样品性能明显优于43℃/min。FGH97粉末高温合金在750℃/450MPa条件下的蠕变机制为位错切割γ′相,在晶界处产生应力集中导致裂纹的萌生,裂纹沿着晶界碳化物扩展,最终导致材料的断裂。弥散颗粒状分布的碳化物能有效抑制微裂纹的贯通。     

长期时效对FGH96粉末高温合金组织稳定性及性能的影响

研究了FGH96粉末高温合金经750℃长期时效1000和3000 h后的晶粒尺寸、晶界形貌、晶粒取向、γ'强化相和碳化物的演变规律及长期时效对合金650℃使用温度下拉伸性能的影响.结果 表明:750℃长期时效对合金的晶粒尺寸、晶界形貌和晶粒取向没有明显影响.然而,长期时效后,合金中γ '相形貌、尺寸和分布发生了显著的变化,大尺寸γ'相先长大后分裂再变小,平均尺寸变大、尺寸梯度降低、间距变大,由双峰分布最终演变为单峰分布;形貌由近球形、方状和蝶状先演变为不规则状,最终又演变回近球状、方状与蝶状.未长期时效合金的晶内和晶界处存在大量富含Ti、Nb元素的块状MC型的碳化物,并与MB型硼化物共存,经750℃长期时效3000 h后没有明显变化.而富含Cr元素的M23C6型小颗粒碳化物经750 ℃长期时效3000 h后,析出量增加并呈链状分布于晶界.长期时效后,FGH96合金650℃拉伸强度降低,塑性提高,主要原因是合金中的γ'相分裂、粗化及晶界处M23C6型碳化物析出呈链状分布所致.     

560 ℃时效处理对GH4145合金螺栓组织的影响

研究了GH4145合金螺栓560 ℃时效处理后,显微组织、晶粒尺寸及γ'相形态的变化。试验结果表明：供货态GH4145合金螺栓560 ℃时效处理50 h,小尺寸晶粒数量显著增多,碳化物析出相数量有所减少,析出大量细小的球状γ'相;相对于时效处理50 h试样,时效100 h小尺寸晶粒和细小的球状γ'相显著长大;时效时间延长晶粒尺寸基本保持不变,球状γ'相最终达到尺寸均一化;时效过程中方形γ'相逐渐分解直至消失。     

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