Superplasticity and Diffusion Bonding of Ti_3AI Intermetallic Compounds

The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.TheTi-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10~(-5) s~(-1) and950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strainrate of 4.52×10~(-5) s~(-1) and the same temperature,and it was found that the elongation value in-creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al-loys were bonded by diffusion bonding technology and good joints were created,the simulatedspecimens were performed by SPF/DB process.     

Model for Superplastic Deformaton of Ti_3Al Alloy

The method is recently developed to obtain the optimum superplastic property of Ti_3Al alloys. Mode is established, and after the calculation to analyze the present model the parameters is found fit to the curve expressing the high plastic well here. mKn is the found turn in these three parameters which causes the super-plasticity effectively, this effect may be studied further to demonstrate it to be effective definitely.     

Ti_3Al+11Nb合金的氧化及Nb的作用

用光学金相、扫描电镜、X射线衍射仪、电子探针等方法对Ti3Al+11Nb合金经高温氧化后的表面状况、断口形貌、显微组织、氧化层结构、元素在氧化层中的分布等氧化特征进行分析,并讨论了Nb对该合金抗氧化性能的影响。     

Diffusion Bonding of Dissimilar Intermetallic Alloys Based on Ti_2AlNb and TiAl

Direct diffusion bonding of an orthorhombic Ti 2 AlNb base alloy to a TiAl base alloy, Ti-22Al-23Nb-2Ta and Ti-46.2Al-2Cr-2Nb-0.15B (at. pct), was carried out and the interface microstructure, formation of new phase at the interface and joint strength were characterized. At low temperature, a new phase with AlNb 2-structure, Al(Nb, Ti) 2 , was formed in the interface region adjacent to the O base alloy. The α 2 was found to be the major reaction product and developed in the interface region adjacent to the ...     

TiAl涂层对Ti_3Al合金腐蚀行为的影响

利用磁控溅射的方法在Ti_3Al合金上溅射Ti-48Al-8Cr-2Ag (原子分数/%)涂层,研究涂层对Ti_3Al合金熔盐热腐蚀和电化学腐蚀行为的影响.同时通过TEM,SEM,EDX,电化学工作站对合金的腐蚀进行研究,并对腐蚀机理进行探讨.结果表明:在熔盐热腐蚀中,涂层对基体具有很好的防护作用,这主要是因为Ti_3Al合金表面发生了大面积的脱落,而涂层试样表面腐蚀膜结合牢固.经过电化学腐蚀研究,涂层试样表面发生明显的分级钝化现象,表明涂层在Na2SO4+K2SO4溶液中具有很好的钝化性能,显示了很好的抗电化学腐蚀性能.     

Diffusion Bonding of Laser Surface Melted Nickel Alloy Material

Diffusion bonding studies were performed on Laser Surface Melted (LSM) Ni-Cr-Fe material. LSM generates metastable microstructures with extended solid solution. The rapid quenching associated with LSM generates a zone that is void of intragranular precipitates, consists of well-defined grain boundaries via intergranular carbides, and contains fine-grained material. Grain growth across the bondlineand precipitate morphology were studied as a function of laser beam power (energy density) and bonding temperature. LSM at low energy density produced excellent grain growth across the bondline even when bonding at low temperature.     

Diffusion Bonding of Silicon Carbide Particulate Reinforced 2024 Al Composites

1. IntroductionCompared with the matriX alloy, SiC particulatereiliforced Al composites (SiCp/AI) have superiorproperties, especially in increased stiffness, highstrength and modulus (for example, a 50% increasein modulus achieved by substituting a discootinuous SiC reinforced Al alloy for an unreinforced counterpart), good wear resistance, and excellellt elevated temperature properties (enhanced creep resistance). This kind of material is generally reasonably isotropic, easier to manufact…     

Ti_3Al金属间化合物的熔盐热腐蚀

采用电化学方法并结合扫描电镜、X 射线衍射、电子探针和能谱等物相分析技术研究了 Ti_3Al 金属间化合物在800℃熔融 NaCl-(Na,K)_2SO_4体系中的腐蚀行为。结果表明,Ti_3Al 合金耐熔盐腐蚀性能远低于 Ni 基 IN738合金。腐蚀时在合金表面形成外层为 TiO_2;内层为富 Nb 的Nb_2O_5,Al_2O_3,TiO_2的混合层和中间层为富 Al 的 TiO_2,Al_2O_3混合层的多层腐蚀层结构。Ti 快速向外扩散和氧向内扩散使合金表面腐蚀产物层迅速增厚。腐蚀产物内层的富 Nb 氧化物破坏了膜层与合金基体的粘附性。     

NiCuMn对C/Al扩散焊界面结合性能的影响

研究了高强碳纤维镀Ni和镀NiCuMn对C/Al扩散焊界面结合性能的影响,重点分析了Mn元素提高C/Al界面结合性能的机理,并根据不同锰含量下的δ和σc值,建立了δ与σc的数学模型。     

Ti_3Al－Nb合金显微组织的研究

用透射电镜和ｘ射线能谱分析研究了Ｔｉ_３Ａｌ－Ｎｂ合金（Ｔｉ－２４Ａｌ－１４Ｎｂ－３Ｖ－０．５Ｍｏ）不同热处理状态下的组织结构。结果表明,Ｔｉ_３Ａｌ－Ｎｂ合金经α_２＋β两相区固溶１ｈ水冷处理以及经８５０℃时效２４ｈ空冷处理时,其显微组织由α２相、β２相和″０″相组成;低温区固溶处理,降低冷却速度以及固溶化时效处理均会有针状α２相析出,随着固溶温度的降低,α２相和″０″相的数量逐渐增多。     

置氢质量分数0．4％Ti600合金扩散连接

进行了置氢质量分数0.4%的新型高温钛合金Ti600的真空扩散连接及接头力学性能测试,利用光学金相(OM)、扫描电镜(SEM)分析手段研究了连接工艺参数对界面孔洞弥合的影响以及拉伸断口特点.结果表明:氢元素能够显著提高扩散连接界面孔洞弥合率;随着连接温度的升高、连接时间的延长以及连接压力的增大,界面孔洞逐渐减少;当连接温度T=875℃,保温时间t=60min,焊接压力P=5MPa时,实现置氢Ti600的良好扩散结合,界面扩散孔洞消失;接头室温拉伸强度达1013MPa,为等条件下母材强度的96%,断口呈明显韧窝形貌.     

IC6合金NiCoCrAlY涂层在制造过程中的修复研究

研究了适用于IC6合金的NiCoCrAlY涂层在制造过程中的修复对涂层本身及IC6合金基体的显微组织和力学性能的影响。结果表明，与原始态涂层相似，修复态涂层通过扩散层与基体紧密结合，涂层/基体界面还没有任何孔洞和裂缝，各元素在涂层、基体之间存在明显的浓度梯度，而且涂层修复对IC6合金的显微组织和力学性能均没有明显影响，经过1100℃/90MPa持久试验后，原始态涂层和修复态涂层与IC6合金基体之间都发生了明显的互扩散，涂层中Mo含量上升到16%（质量分数，下同）左右，而Cr和Co含量下降至5%左右，但涂层仍然与合金基体结合紧密，因此，NiCoCrAlY涂层在制造过程中的修复是可行的。     

Ti_3Al超塑性扩散连接的理论计算

研究了Ti3 Al超塑性扩散连接的物理模型和数学模型 ,对Ti3 Al超塑性扩散连接的工艺过程进行了理论计算 ,探讨了工艺参数对Ti3 Al超塑性扩散连接质量的影响 .     

Ti_3Al和Ti_2AlNb合金扩散连接界面的组织及力学性能

采用直接扩散连接Ti3Al和Ti2AlNb合金,研究了连接压力、连接温度、保温时间等工艺参数对接头界面组织形貌及性能的影响。利用扫描电镜、能谱分析和X射线衍射等方法观察分析了界面组织结构,并测试了接头的力学性能。结果表明:直接固相扩散连接接头的典型组织为Ti3Al/O相+α2相过渡层/富B2层/Ti2AlNb。当连接温度为1000℃,保温时间60min,连接压力为5MPa时获得的接头室温抗剪强度为635MPa,室温抗拉强度为795MPa,均断裂于Ti3Al母材一侧。经1000℃/60min热循环后Ti3Al母材的抗拉强度下降至原始母材的76%。连接温度低于950℃或保温时间小于60min会导致未焊合等缺陷;温度高于1050℃或保温时间超过120min则导致Ti3Al发生相变。     

Phase Transformation and Deformation Mechanism of Ti_3Al-base Alloy

The phase transformation and deformationmechanism of the alloy based on composition Ti_3Alwith addition of Nb,V,Mo have been studied by useof transmission electron microscopy (TEM).It hasbeen shown that the orientation relationship ofα_2 phase transformed from β phase is:(0001)α_2//(l10)β,[1210]α_2//[111]β.The present dislocationslip systems in α_2 phase are (1100)[0001] and(1100)<1120>.There also exist α_2 twins whichhave new twin relationship and the twin plane is(2021).     

焊前处理方式对LF6铝合金扩散焊的影响

利用Ｇｌｅｅｂｌｅ－１５００热／力模拟试验机，研究了ＬＦ６铝合金的扩散焊工艺，通过对焊接温度、压力、时间的调整和选用不同的料前处理方法，确定了最佳的扩散规范，研究结果表明：在一定的温度和时间范围内，ＬＦ６５铝合金扩散焊接头的剪切哟度随焊接温度和时间的增加而提高；化学浸蚀法比机械打磨法能更有效的去除铝合金表面的氧化膜；在现有试验条件下，得到ＬＦ６铝合金扩散焊的最佳规范参数，搭接试扩散焊接头的剪切强度     

Dissolution Mechanism of a Zr Rich Structure in a Ni_3Al Base Alloy

In the present research,the dissolution mechanism of a Zr rich structure during annealing of a Ni 3 Al base alloy containing Cr,Mo,Zr and B,was investigated.The annealing treatments were performed up to 50 h at 900,1000 and 1100 C.The alloy used in this investigation was produced by vacuum-arc remelting technique.The results show that at the beginning of the process,a mixed interface reaction and local equilibrium(long range diffusion) mechanism controls the dissolution process.After a short time,this mechanism changes and the dissolution mechanism of the Zr rich structure changes to only long range diffusion of Zr element.According to this mechanism,the activation energy of this process is estimated to be about 143.3 kJ·mol 1.Also the phases that contribute to this structure and the transformations that occur at the final steps of solidification of this alloy were introduced.According to the results,at the final step of solidification,a peritectic type reaction occurs in the form of L+ γ’→γ+Ni 7 Zr 2 and γ-Ni 7 Zr 2 segregates from the melt.Following this transformation,γ-Ni 7 Zr 2 eutectic separates from the remaining Zr rich liquid.The solidification process will be terminated by a ternary eutectic reaction in the form of L→γ+Ni 5 Zr+Ni 7 Zr 2.     

Ti_3Al基合金的高温蠕变－疲劳行为

本文测试了两种热处理状态下的Ｔｉ_３Ａｌ（ＮｂＭｏｖ）合金在７００℃时保持最大应力恒定、改变最小应力１Ｈｚ梯形波加载条件下的疲劳断裂寿命。结果表明，随平均应力增高将导致蠕变损伤加重，致使Ｓ－Ｎ曲线反向。在相同应力幅时，于β相区固溶的样品比在两相区固溶的样品具有较高的蠕变－疲劳抗力。最后发现，这些宏观性能的变化与稳态应变速率和微观断裂特征是密切相关的。     

铝含量对Ni_3Al基合金IC6E微观组织和力学性能的影响EI

为了确定Ni3Al基合金IC6E中最佳的铝含量,在成分为Ni-14.0Mo-7.2Al-0.025B(质量分数/%,下同)的母合金中,分别加入了四种不同含量的铝(0%,0.4%,0.6%,0.8%),测定了这些合金的室温拉伸和1050℃/90MPa高温持久性能,并采用扫描电镜分析了这些合金的微观组织。综合考虑这些合金的微观组织以及力学性能,确定了在IC6E合金中最佳的铝含量为7.8%。     

LF6铝合金的超塑性／扩散连接组合工艺试验及理论研究EI

本文研究了ＬＦ６铝合金的超塑性／扩散连接组合工艺，用变形和再结晶的方法细化晶粒，成功地进行了ＳＰＦ／ＤＢ工艺试验，利用电子探针观察了扩散连接接头的界面微观区域，并从机理上分析了金属的超塑性／扩散连接两种工艺之间的内部联系及其金属学行为。