一种镍钴基变形高温合金蠕变变形机制的研究

研究了一种新型镍钴基变形高温合金在650—815℃和不同加载载荷条件下蠕变后的变形组织.结果表明,经过固溶热处理后合金中存在2种尺寸的γ′相.当蠕变温度高于725℃时,大γ′相开始粗化.蠕变温度为650℃时,合金主要通过位错滑移切割γ′相形成层错的方式变形;蠕变温度在725—760℃之间时,蠕变变形组织主要为层错和微孪晶.随着加载载荷和蠕变温度的升高,层错和微孪晶不再独立存在于γ′相中,而是贯穿γ′相和基体;当蠕变温度升高至815℃时,合金主要通过位错绕过γ′相的方式变形.     

新型高性能镍基粉末高温合金拉伸变形行为和机制研究

采用SEM和TEM研究了室温(23℃)和中温(650、750、815℃)下第3代镍基粉末高温合金(FGH98)拉伸变形显微组织、行为和机制。结果表明:含有多模尺寸分布γ′相的合金具有优良的拉伸性能,室温拉伸主要变形机制为位错剪切γ′相形成层错,并在γ′相周围形成位错环,阻碍后续位错运动。中温拉伸变形机制为位错剪切γ′相形成层错和形变孪晶,随着变形温度的升高,形变孪晶增多。给出了a/3112不全位错剪切γ′相形成层错和形变孪晶共存的模型,随着应变量的增加,在连续相邻的{111}滑移面上层错堆积变多,促进连续孪晶的形成,协调了γ和γ′相两相之间的变形,有助于释放两相之间的变形应力和提高合金强韧性。     

新型镍钴合金的高温蠕变行为研究

研究了新型镍钴合金的高温蠕变行为。结果表明,当蠕变温度为625℃时,其显微组织主要是扩展位错层;当蠕变温度为700℃时,其显微组织主要是扩展位错层和变形微孪晶;当蠕变温度为800℃时,其显微组织主要为粗大的γ′相。     

Ta含量对镍基粉末高温合金高温蠕变变形行为和性能的影响

采用FESEM、TEM等实验技术,系统研究了750℃、600 MPa条件下,不同Ta含量的镍基粉末高温合金的蠕变性能和蠕变过程中显微组织和变形行为特征以及合金层错能对蠕变行为的影响.结果表明,随着Ta含量的增加,合金层错能呈非线性关系降低.蠕变变形各阶段的变形行为和位错组态的变化与层错能密切相关.低Ta含量合金层错能相对较高,基体位错a/2<110>滑移被阻止在γ/γ'内界面处,不易发生位错分解,可直接进入γ'相中形成反相畴界(APB)或通过Orowan环弓弯模式绕过γ'相;当合金中Ta含量中等时,合金层错能降低,促进在γ/γ'内界面处基体位错发生分解,产生a/6<112>Shockley不全位错开始剪切γ'相,形成超点阵层错(超点阵内禀层错(SISF)或超点阵外禀层错(SESF))和扩展层错(ESF)进而转化形成形变孪晶,呈现层错和形变孪晶共同强化效应,提高蠕变性能;而高Ta含量合金层错能很低,有利于位错在不同{111}滑移面上同时形成尺寸较宽的扩展层错,并出现相互交结的交叉层错抑制形变孪晶的形成,加快蠕变形变裂纹发展.因此,合金中加入适量Ta能有效降低层错能,提高形成不全位错剪切γ'相能力和形成显微孪晶能力,增加蠕变抗力,有效改善合金蠕变性能.     

层错能和温度对不同Co含量的镍基高温合金蠕变性能的影响

研究了2种不同Co含量的镍基高温合金分别在650 °C/630 MPa,725 °C/630 MPa和760 °C/630 MPa条件下的蠕变变形组织。通过透射电镜分析了温度和层错能对蠕变变形机制的影响。结果表明,对于所选取的高温合金来说,温度的提升可以有效促使蠕变变形机制由层错转变为孪晶。这表明孪晶的形成更大程度上取决于温度。此外,合金Co含量的提升以及层错能的下降都会使层错和孪晶延伸并穿过γ基体和γ′析出相,该方式提升了材料的蠕变抗力以及蠕变寿命。     

固溶温度对FGH95合金组织和持久性能的影响

通过对不同工艺处理FGH95合金进行组织形貌观察及持久性能测试,研究了固溶温度对合金组织与持久性能的影响.结果表明:经热等静压后,合金的组织结构由不同尺寸的γ'相和γ基体所组成;经1140℃较低温度固溶及时效处理后,在颗粒边界区域仍存在较多粗大γ'相和γ'相贫化区,随固溶温度提高,粗大γ'相及γ'相贫化区数量减少.当固溶温度提高到1160℃,合金中粗大γ'相完全溶解,γ'相贫化区消失,且高体积分数细小γ'相在晶内弥散分布,并有粒状MC型碳化合物在晶内及沿晶界不连续析出,可改善晶界的结合强度,使合金在650℃、1034 MPa条件下具有较高的持久强度.在蠕变期间合金的变形机制是位错以Orowan机制饶过γ'相和位错切割γ'相,其中,<110>位错切人γ或γ'相时,可分解形成(1/6)<112>肖克莱不全位错或(1/3)<112>超肖克莱不全位错+层错的位错组态.     

FGH95镍基合金的蠕变行为研究

研究了FGH95镍基合金在650℃、1 040 MPa条件下的蠕变行为。结果表明,在蠕变初期,基体中的位错开始形成并呈现出六边形特征,随着蠕变的进行,位错交织在一起。当蠕变进行到100 h后,位错出现在γ和γ′相之间交界处,增强了合金的抗蠕变能力。当蠕变进行到280 h之后,在γ和γ′相交界处的位错呈现出四边形特征,导致该处应力集中,γ′相位错遭到破坏,这时基体中的蠕变位错就会运动到γ′′相之中并形成不全位错和层错的位错组态。     

TiAl-Nb合金在近750℃温度区间的蠕变行为

通过蠕变性能测试和组织形貌观察,研究了铸态TiAl-Nb合金在近750℃施加不同应力条件下的蠕变损伤行为。结果表明,合金的组织由不同取向的层片状γ/α_2两相组成,不同取向层片状组织的晶界为单一γ相。铸态合金在(750℃,300 MPa)蠕变期间的变形机制是位错和孪晶,且位错在层片状γ/α_2两相及孪晶中滑移。随蠕变进行,激活的位错数量增加,当蠕变位错与位错网相遇,可改变位错的运动方向,促进发生位错攀移,减缓应力集中。在蠕变后期,大量位错在近相界区域塞积,引起应力集中,可致使裂纹沿垂直于应力轴的层片状γ/α_2两相界面萌生与扩展,当不同横断面的裂纹通过撕裂棱相互连接,直至发生断裂,是合金在近750℃蠕变期间的损伤与断裂机制。     

热挤压态FGH96粉末冶金高温合金的显微组织与力学性能

以热挤压态镍基粉末冶金高温合金FGH96为研究对象,研究该合金横向(垂直于挤压方向)和纵向(沿挤压方向)试样的显微组织及力学性能,分析断裂机制和变形后的显微组织。结果表明:FGH96合金横向及纵向试样均为无明显织构的等轴晶组织,且平均晶粒尺寸及γ'相体积分数基本一致。在应变速率1×10~(-4)s~(-1)时,横向和纵向拉伸试样抗拉强度在25~650℃温度区间内随温度升高缓慢降低,当温度高于650℃时,抗拉温度下降速率显著增加;且横向试样的抗拉强度低于相同实验条件下纵向试样的抗拉强度,差值为150~200 MPa;失效机制为从室温条件下的穿晶断裂转变为混合断裂模式,横向试样的转变温度为400℃左右,纵向试样的转变温度约为650℃;横向试样变形后,显微组织有高密度的位错缠结及层错;纵向试样拉伸断裂后,显微组织则主要为孪晶及位错与γ'相的交互作用。     

Ti-47Al-5Nb合金高温循环变形后的组织和断裂特征

为研究新一代高Nb含量γ-TiAl合金在低周疲劳过程中双态组织稳定性对应力-应变响应和疲劳断裂过程的影响，测试了Ti-47Al-5Nb合金在总应变控制条件下550℃～750℃温度范围的低周疲劳性能，并观察了循环变形后的显微组织，缺陷特征和断口形貌。结果表明：在550℃变形时所产生的循环硬化缘于不均匀的位错滑移，在滑移带内高密度位错之间产生强烈的相互作用降低了位错的可移动性，滑移带产生的应力集中使裂纹易于沿α2/γ层界面扩展。在650℃和750℃变形时的循环软化则一方面归因于部分α2片层溶解和γ相再结晶，另一方面大量孪晶的激活和位错通过交滑移和攀移克服短程障碍的作用使合金的变形能力提高，同时增加了疲劳过程中的塑性应变累积。疲劳断口特点为等轴γ晶和α2/γ层的穿晶断裂。     

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。     

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.     

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.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

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     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

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 on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

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.