硼化物原位自生增强TiAl基复合材料的组织演化、热变形行为及加工工艺设计（英文）

硼元素添加造成的相转变和硼化物析出等因素会对原位TiAl基复合材料显微组织演化及热变形行为产生影响。利用等温压缩实验、扫描电子显微技术以及透射电子显微技术等研究材料的动态再结晶和动态回复机制,并计算出其表现变形激活能为691.506 k J/mol。在1100～1200℃温度区间,再结晶γ和α晶粒的形核长大分别主导α₂→α相转变温度上、下的热变形行为。α相的动态回复主导材料在1250℃低应变速率下的热变形行为;同时,硼元素会提高α相含量,降低γ→α和α₂→α相转变温度,进而促进加载过程中回复α相晶粒的形核长大。根据新建的本构模型,对TiAl基复合材料的变形机制和加工工艺进行详细阐述.     

连接温度对TiAl/Ti3AlC2扩散焊接头界面结构及性能的影响

采用Ti/Ni复合中间层实现了TiAl合金和Ti₃AlC₂陶瓷的扩散连接,利用SEM,XRD等分析方法对接头界面结构进行了分析.结果表明,TiAl/Ti₃AlC₂接头典型界面结构为TiAl/Ti₃Al+Al₃NiTi₂/Ti₃Al/α-Ti+Ti₂Ni/Ti₂Ni/TiNi/Ni₃Ti/Ni/Ni₃(Ti,Al)/Ni₃Al+TiC_x+Ti₃AlC₂/Ti₃AlC₂.随着连接温度的升高,TiAl/Ti界面处的Ti_ss层逐渐减小,Ti₃Al化合物层逐渐变厚;TiNi化合物层厚度显著增加,Ti₂Ni和Ni₃Ti层厚度基本保持不变.接头抗剪强度随连接温度升高先增加后减小,当连接温度为850℃时,接头的抗剪强度最高可达到85.3 MPa.接头主要在Ni/Ti₃AlC₂界面及Ti₃AlC₂基体处发生断裂.     

预热温度对GTA增材制造钛铝合金组织及性能的影响

高温结构材料TiAl金属间化合物的可加工性较差,复杂结构成形技术难度大,制造成本高. 电弧增材可以实现TiAl基合金的原位低成本柔性制造,但制造过程中仍需注意裂纹控制问题. 预热处理通过改善组织可以有效抑制裂纹产生. 文中以Ti6Al4V与ER1100纯铝焊丝作为原材料,在200 ,300,450 ℃的预热温度下利用TIG焊原位合成了铝含量为50% (原子分数)的TiAl基合金,考察了不同预热温度下TIG电弧增材制造的钛铝合金的组织与力学性能. 结果表明,随着预热温度的增加,构件的顶部与中部区域逐渐在γ/α₂层片团的晶界析出更多的块状γ相,底部组织变化不明显. 预热温度的增加使得合金中γ相增多而α₂相减少,导致合金室温硬度减少. 同时,弥散分布的块状γ相的增多,使得构件的压缩性能提升,当预热温度为450 ℃时,构件抗压强度与压缩率最高.     

铜包覆Ti2AlC增强铜基复合材料的制备及性能

通过化学镀技术在Ti₂AlC粉体表面镀上一层金属铜，然后以铜粉、镀铜Ti₂AlC粉为原料，采用烧结法制备了10%Ti₂AlC/Cu复合材料。结果表明：化学镀铜溶液pH为11～12时，Ti₂AlC粉体表面的铜镀层光滑致密、不易脱落。10%Ti₂AlC/Cu复合材料的组织分布均匀，镀铜Ti₂AlC颗粒与铜基体结合紧密；复合材料相对密度为94.31%,导电性能和硬度相对于纯铜稍有下降；复合材料的平均摩擦系数随着载荷的增加稍微下降，从10 N时的0.4862到30 N时的0.3858,相对于纯铜有明显降低；复合材料的磨损率随着载荷增加逐渐下降，从10 N时的0.208 g·N^-1·m^-1变为30 N时的0.147 g·N^-1·m^-1。表明复合材料具有较好的耐磨性。     

NbMoWTa-Al2O3固体润滑复合材料的宽温域摩擦磨损性能

通过高能球磨和放电等离子烧结方法制备了新型NbMoWTa难熔高熵合金基固体润滑复合材料。系统研究了纳米Al₂O₃作为固体润滑剂对NbMoWTa难熔高熵合金宽温域摩擦学性能的影响。结果表明：纳米Al₂O₃颗粒在具有BCC结构的NbMoWTa难熔高熵合金基体相晶界和晶内均匀分散,强烈的弥散强化显著提升了NbMoWTa的显微硬度。纳米Al₂O₃颗粒在室温至800℃范围内降低摩擦因数和磨损方面有显著作用。室温下,由于复合材料的显微硬度显著提升,添加足量的纳米Al₂O₃实现了复合材料耐磨性的提升。在中高温下,复合材料表面形成的连续致密氧化摩擦层对提升摩擦学性能起着关键作用。纳米Al₂O₃颗粒协助氧化摩擦层承载更大的载荷,提高其致密性及稳定性,从而更有效地保护基体。此外,在800℃下纳米Al₂O₃颗粒的存在能够抑制MoO3的过度挥发。     

Ta含量对多相增强CuZr基非晶复合材料组织性能的影响

针对Cu-Zr-Al-Sn非晶复合材料中B2-CuZr相析出不均匀,尺寸较大的问题,向体系中添加Ta元素,旨在通过高熔点富Ta相的析出,促进B2-CuZr相的异质形核与均匀分散,制备多相增强CuZr基非晶复合材料。研究了不同Ta添加量时复合材料的组织与性能的演化规律,发现引入的富Ta相可成为B2-CuZr相的有效异质形核基底,调控B2-CuZr相的析出量、尺寸和分布,形成的多相增强结构可有效改善合金的力学性能。随着Ta含量增加,试样的屈服强度逐渐降低,塑性变形能力先增加后减小,性能最优异的[(Cu_0.5Zr_0.5)_0.925Al_0.07Sn_0.005]₉₇Ta₅非晶复合材料的抗压强度达到2 214 MPa,塑性应变达到4.3%。     

热压工艺对SiCf/Ti复合材料界面反应层生长影响的数值模拟

提出一个热-力-扩散-反应强耦合相场模型来研究热压烧结制备工艺对连续碳化硅纤维增强钛基复合材料中金属间化合物生长规律的影响。模拟结果表明,在两种不同温度下各个界面反应层(Ti₃SiC₂/Ti₅Si₃C_x/Ti₅Si₃C_x+TiC/TiC)的厚度生长与试验值吻合较好。增大外加压力能促进界面层厚度的生长,但对其中抗拉强度最低的Ti₅Si₃层的生长起显著的抑制作用,同时使各界面反应层由周向拉应力状态逐渐转变为压应力。温度的升高使断裂韧度最大的Ti₃SiC₂层厚度增大,但也使总界面层和Ti₅Si₃层的厚度增加。因此,在制备工艺上适当增加压力并选择合适的温度,得到厚度适宜的界面反应层的同时,尽可能使Ti₅Si₃层变薄和Ti₃Si...     

TA10钛合金热连轧板材显微组织及其性能

研究了930℃下的热连轧对Ti-0.3Mo-0.8Ni钛合金板材显微组织与室温力学性能的影响。结果表明，热连轧有效破碎了TA10钛合金中α+Ti₂Ni层片组织，获得了α基体、晶界Ti₂Ni颗粒、α基体内弥散分布细小β相颗粒的显微组织，其中晶界Ti₂Ni和基体内β颗粒平行于轧向呈带状分布。相对于铸态组织，热连轧板材中Ti₂Ni颗粒周边存在贫Mo过渡区，而α-Ti基体内发现细小弥散分布的β颗粒，其周边无明显贫Mo过渡区。变形组织中α基体具有较强的织构，相应板材室温力学性能表现出较强的各向异性，横向杨氏模量、屈服强度和抗拉强度都高于轧向的。     

碳纳米管含量对TiAl基合金微观组织及室温力学性能的影响

首先采用超声波震荡和机械球磨的方法将碳纳米管(CNTs)粉末和Ti-48Al-2Cr-8Nb(原子分数,%)预合金粉末制备成混合粉末,随后通过放电等离子烧结技术(SPS)制备了CNTs/Ti-48Al-2Cr-8Nb复合材料,研究了CNTs含量对复合材料的相组成、微观组织和室温力学性能的影响。结果表明:随着CNTs含量的增加,反应生成的TiC和Ti₂AlC碳化物的含量会增加,而TiC、Ti₂AlC相可以细化晶粒尺寸,起到细晶强化作用,同时TiC、Ti₂AlC相作为硬质陶瓷相也可以起到强化作用;当CNTs含量为0.4%时,复合材料的平均晶粒尺寸由60μm细化到32μm,密度、硬度和抗弯强度分别为4.294 g/cm³、377 HV20和879 MPa,断裂模式主要为穿晶断裂;当CNTs含量较多时,由于CNTs分散不均匀,反应生成的碳化物会发生团聚现象,造成复合材料会产生凹坑、裂纹等缺陷,降低其室温力学性能。     

以Ti-Zr-Cu-Ni-Fe合金为中间层的Ti3Al/TiAl瞬间液相扩散连接

采用瞬间液相扩散焊方法,以自主设计的Ti-Zr-Cu-Ni-Fe系新型合金作为中间层,实现了Ti₃Al基合金与TiAl异种材料之间的连接.利用扫描电镜、电子探针以及X射线衍射分析等方法对接头界面微观组织和物相进行了分析.结果表明,Ti₃Al/TiAl接头主要由富Ti相、Ti₂Al反应层、α₂-Ti₃Al相以及溶入了Al元素的残余中间层组成;随着焊接温度的升高,中间层与母材的溶解与扩散变得更加强烈,使得Ti₂Al反应层厚度增加,残余中间层的数量减少.抗剪测试结果显示,焊接接温度在880~1010℃范围内时,提高焊接温度有利于接头强度的提高;接头在室温下的最大抗剪强度达到502 MPa,在500℃下为196 MPa.     

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.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.