B元素对Ti-46Al和Ti-46Al-5Nb合金柱状晶组织的影响

B元素对Ti-46Al和Ti-46A1-5Nb(原子分数,%)合金的柱状晶组织均有明显的细化作用,且对后者的细化效果更显著.这一现象可归结为:B元素在Ti-46Al-5Nb合金中的溶解度较低,硼化物析出量增加,柱状晶组织进一步细化.     

SiCf/Ti-6Al-4V复合材料的界面研究

采用扫描电镜、透射电镜和X射线衍射仪研究了用中国制备SiC纤维增强的Ti-6Al-4V复合材料的界面反应,发现在SiC纤维的C涂层和Ti-6Al-4V基体之间形成的界面反应产物为细晶粒和粗晶粒的TiC,而无C涂层的SiCf/Ti-6Al-4V的界面反应产物,从SiC纤维到Ti-6Al-4V基体,依次为细晶粒的TiC+Ti5Si3、粗晶粒的TiC和Ti3SiC2.还测量了界面反应区厚度并讨论了界面反应机理.     

SiCf/Ti-6Al-4V复合材料界面反应动力学

SiC纤维增强Ti基复合材料（SiCf／Ti）容易发生界面反应，从而影响其力学性能。开展界面反应和动力学的研究，对于SiCdTi复合材料的制备和服役具有指导意义。采用扫描电镜、透射电镜和X射线衍射分析了SICf／Ti-6Al—4V复合材料的界面反应及其动力学，发现SiC纤维的C涂层与Ti-6Al—4V反应形成粗晶粒的和细晶粒的TiC，长期高温热处理使得界面反应加剧，TiC层加厚，当C涂层完全消耗后，界面反应层中除了TiC外，还出现了Ti3SiC2。研究表明，界面反应层的加厚受元素扩散控制，服从抛物线规律，求出的动力学参数Q为268．8kJ／mol，k为0．0057m/s1/2。     

SiCf／Ti-6AI-4V复合材料的界面研究

采用扫描电镜、透射电镜和x射线衍射仪研究了用中国制备SiC纤维增强的Ti-6AI-4V复合材料的界面反应，发现在SiC纤维的C涂层和Ti-6AI-4V基体之间形成的界面反应产物为细晶粒和粗晶粒的TiC，而无C涂层的SiCf／Ti．6AI．4V的界面反应产物，从SiC纤维到Ti-6AI-4V基体，依次为细晶粒的TiC＋Ti5Si3、粗晶粒的TiC和Ti3SiC2。还测量了界面反应区厚度并讨论了界面反应机理。     

Microstructure and mechanical properties of Ti-6Al-4V/Ti-22Al-25Nb joint formed by diffusion bonding

Ti-6Al-4V (wt.%) and Ti-22Al-25Nb (at.%) were joined by diffusion bonding at 950 °C and 15 MPa for 100 min, and the microstructure and mechanical properties of the resulting joints were investigated. The composition of the diffusion layer is B2/discontinuous α/α₂ layer/necklace-shaped β+α′ layer, where the content of any element at a given point mainly depends on the distance of the point from the interface and the phase type at the point. The tensile strength of the joint is 894 MPa, which is almost the same as that of the Ti-22Al-25Nb base alloy. The fracture surfaces on both sides of the joint are composed of two main regions. One region displays a relatively flat surface and fractures along the bonding interface. The other is composed of a moderate number of irregularly-shaped cavities on the Ti-6Al-4V side and many irregularly-shaped bulges on the Ti-22Al-25Nb side. Both regions result from fracture along the boundaries between β+α′ layers and α_p grains or from the transcrystalline fracture of α_p grains.     

Effects of yttrium on microstructures and properties of Ti- 17Al-27Nb alloy

1 Introduction With the rapid development in aerospace technology, the aero engine components have to endure larger force and higher temperature due to speed increase of aero-craft. Therefore, more requisitions have to be presented when selecting material…     

SiCf/Ti-6Al-4V复合材料的断裂韧性

采用三点弯曲法测定了SiC纤维单向增强的Ti-6Al-4V复合材料的表观断裂韧性,讨论了界面反应对断裂韧性的影响.研究结果表明,在裂纹尖端塑性变形区的未断纤维的桥联对复合材料的断裂韧性起很大的作用.经过热处理后,SiCf/Ti-6Al-4V复合材料的断裂韧性降低,主要是由于严重的界面反应,使得SiC纤维受到一定的损伤,因而降低了纤维的承载能力,并使基体钛合金的脆性增大.     

Surface characterization of passive film formed on nitrogen ion implanted Ti-6Al-4V and Ti-6Al-7Nb alloys using SIMS

The aim of this paper is to study the effect of N⁺ ion implantation on corrosion and phase formation on the implanted surfaces of Ti-6Al-4V and Ti-6Al-7Nb alloys. Nitrogen ion was implanted on Ti-6Al-4V and Ti-6Al-7Nb alloys at an energy of 70 and 100 keV, respectively using a 150 keV accelerator at different doses ranging from 5 × 10¹⁵ to 2.5 × 10¹⁷ ions/cm². Electrochemical studies have been carried out in Ringer’s solution in order to determine the optimum dose that can give good corrosion resistance in a simulated body fluid condition. The implanted surfaces of such modified doses were electrochemically passivated at 1.0 V for an hour. Secondary ion mass spectroscopy was used to study and characterize titanium oxide and titanium nitride layers produced on implanted surface and to correlate them with the corrosion resistance. The nature of the passive film of the implanted-passivated specimen was compared with the unimplanted-passivated as well as as-implanted specimens.     

热处理对SiC/Ti-6Al-4V复合材料力学性能的影响

测定了经过900℃不同时间热处理的SiC/Ti-6Al-4V复合材料的拉伸强度,并采用全局载荷分配模型计算了复合材料的强度。发现长时间热处理后,复合材料强度的计算值与实测值吻合很好,但该模型对未经热处理的制备态试样的预测值偏高。扫描电镜和透射电镜微观分析表明,随着热处理时间的延长,SiC/Ti-6Al-4V复合材料的界面反应区增厚而SiC纤维的C涂层逐渐消耗,复合材料的界面结合强度逐渐增加但抗拉伸强度逐渐下降。界面反应形成的反应产物主要为TiC,在C涂层消耗完的区域还形成了Ti5Si3。界面反应是使复合材料力学性能变差的主要原因。     

Effect of heat treatment processing on microstructure and tensile properties of Ti-6Al-4V-10Nb alloy

Effects of heat treatment processing on the microstructure and mechanical properties of Ti-6Al-4V-10Nb alloy were investigated. The microstructures were investigated by SEM, TEM and XRD, and the mechanical properties were evaluated by tensile tests at room and elevated temperatures. The results indicate that the lath-like and globular primary α phase, secondary α phase and β phase are obtained after forging and heat treatment processing. The size of secondary α phase is much smaller than that of primary α phase. After heat treatment, the volume fraction of primary α phase is decreased, and that of secondary α phase is increased. With the increase of solution temperature, the volume fraction of primary α phase is gradually decreased, and that of secondary α phase is obviously increased. The yield strength and tensile strength of Ti-6Al-4V-10Nb alloy are significantly enhanced with the solution temperature increasing.     

Nitrogen ion implantation and in vitro corrosion behavior of as-cast Ti-6Al-7Nb alloy

In the present investigation, surface modification of Ti-6Al-7Nb alloy with nitrogen ions is considered as a method to improve its performance with respect to corrosion. Nitrogen ion was implanted on Ti-6Al-7Nb alloy at an energy of 70 and 100 keV using a 150 keV accelerator at different doses between 1×10¹⁶ and 3×10¹⁷ ions/cm². Gracing incidence X-ray diffraction was employed on the implanted specimens to understand the phases formed with increasing doses. The implanted samples were subjected to electrochemical study in Ringer's solution in order to determine the optimum dose that can give good corrosion resistance in a simulated body fluid condition. The OCP of the implanted specimens were found to shift in the noble direction in comparison with unimplanted specimen. The passive current density and area of the repassivation loop were found to decrease as the dose values increased. The electrochemical impedance spectroscopic results indicate that the polarization resistance was higher for the dose of 2.5×10¹⁷ ions/cm² implanted at both energy of 70 and 100 keV. Nitrogen ion implantation enhanced the passivability and reduces the corrosion kinetics of the alloy surface with increasing tendency for repassivation. Nature of the surface and reason for the variation and improvement in corrosion resistance are discussed in detail.     

Ti-6Al-2Zr-1Mo-3Nb合金微弧氧化陶瓷膜的结构与性能

利用微弧氧化技术,在Ti-6Al-2Zr-1Mo-3Nb合金表面制备陶瓷涂层。用扫描电镜和X射线衍射仪观察并分析陶瓷膜层的组织形貌和相结构,用电子万能材料试验机和数字万用表研究膜层的结合强度和绝缘性,并用MMS-1G高温高速销盘摩擦磨损试验机和YWX/Q-750盐雾试验机考察涂层的摩擦性能和耐腐蚀性能。结果表明:陶瓷层主要由金红石TiO2相和锐钛矿TiO2相构成,膜基结合强度达到30MPa以上,膜层绝缘性和耐腐蚀性良好,耐磨性得到明显改善,涂层的磨损机制表现为轻微的磨粒磨损与粘着磨损。     

Ti-22Al-26Nb合金热变形本构方程建立及软化行为研究

作为最具潜力的航空航天高温结构材料,Ti2AlNb基合金具有高的比强度和良好的高温蠕变性能。本文对热轧态Ti-22Al-26Nb合金高温变形中的力学行为和再结晶行为进行研究,建立其高温本构关系模型,对其中呈现出的动态再结晶多应力峰值曲线特征（以1000℃,0.1s-1为例）进行拟合分析。结果表明：基于双曲正弦函数建立Ti-22Al-26Nb合金的高温本构关系模型的精度较高,最大误差为2.6%,可以很好地描述合金在高温变形时各热力学参数之间高度非线性的复杂关系,由修正的Avrami方程预测得知再结晶体积分数与应变呈现典型的再结晶动力学增长趋势,揭示了该合金高温变形过程中复杂的软化行为。     

Ti2AlNb合金超塑性能及四层立筋结构超塑成形/扩散连接工艺

对Ti-22Al-27Nb合金四层结构件SPF/DB组合工艺进行试验研究,对Ti-22Al-27Nb合金的超塑性能及扩散连接性能进行探究。拉伸实验表明,当变形温度为960℃、应变速率为1×10^?4 s^?1时,材料伸长率达到最大,为230%。对温度、保温时间和扩散压力对Ti-22Al-27Nb合金接头质量的影响进行研究,结果表明Ti-22Al-27Nb合金扩散连接的最佳工艺参数为(960℃,10 MPa,2 h)。根据高温拉伸试验结果,利用有限元模拟软件对中空四层结构件超塑成形过程进行模拟。通过SPF/DB组合工艺成形得到外观质量良好的Ti-22Al-27Nb合金中空四层结构件,成形构件壁厚分布均匀。     

Ti-6Al-4V合金的轧制与组织性能

采用光学显微镜、透射电镜和拉伸试验等手段,研究了多道次两向轧制和单向轧制对不同原始状态(热轧态、水淬态和空冷态)Ti-6Al-4V合金显微组织和力学性能的影响。结果表明,热轧态Ti-6Al-4V合金的组织为片状α相+β相+少量等轴α相,水淬态Ti-6Al-4V合金形成了针状马氏体组织,空冷态Ti-6Al-4V合金形成了网状组织。Ti-6Al-4V合金适宜的两向轧制温度为700 ℃,此时合金中可见颗粒状β相弥散分布在α基体上。两向轧制Ti-6Al-4V合金的抗拉强度和屈服强度从高至低顺序为:水淬态>热轧态>空冷态,且轧向强度要高于横向;相较于单向轧制,两向轧制明显降低了Ti-6Al-4V合金板材拉伸性能的各向异性,且水淬态Ti-6Al-4V合金的轧向和横向强度差异最小,700 ℃轧制Ti-6Al-4V合金的主要细化机制为位错细化。     

Comparisons of interface microstructure and mechanical behavior between Ti/Al and Ti-6Al-4V/Al bimetallic composites

The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al bonding was also given as a comparison for understanding the interface bonding mechanism. It is shown that there is much thinner compact sub-layer for the interface of the Ti-6Al-4V/Al joint, whose morphology is obviously different from that of the Ti/Al joint. The Ti-6Al-4V/Al interface has been proven to contain a slight content of vanadium. Moreover, both the shear strength and the interface reaction rate of Ti-6Al-4V/Al compound materials are lower than those of the Ti/Al ones.     

Ti-22Al-26Nb合金的高温氧化行为

采用热重法研究Ti-22Al-26Nb合金在800和900 ℃的高温氧化行为.利用X射线衍射分析(XRD)、扫描电镜(SEM)对氧化膜的相组成和形貌进行分析.结果表明:在氧化初期该合金遵循抛物线规律,而20 h以后,合金的氧化动力学符合直线规律.氧化后的产物主要由TiO_2、AlNbO_4和Nb_2TiO_7组成,氧化膜出现了分层结构且氧化温度愈高,分层愈明显.     

Ti-22Al-27Nb合金的晶粒长大行为

通过测量Ti-22Al-27Nb合金的晶粒尺寸并进行拟合计算,研究了Ti-22Al-27Nb合金在不同等温退火温度及时间下的晶粒长大行为。结果表明,随着等温退火温度、时间的增加,Ti-22Al-27Nb合金的晶粒尺寸呈现增加的趋势,但随着等温退火时间的延长,晶粒尺寸的长大速度呈现降低的趋势。等温退火温度为1070 ℃,合金的晶粒长大生长指数为0.38;而当温度升高至1090 ℃时,生长指数达到了0.44。随着等温退火时间的增加,Ti-22Al-27Nb合金的晶粒长大激活能呈增加趋势,范围在132.8~267.2 kJ·mol^-1。     

Ti-6Al-4V钛合金固体渗硼法表面改性

对TC4钛合金(Ti-6Al-4V)进行表面渗硼使其表面硬度显著提高.渗硼温度为1000℃到1050℃,渗硼时间为5 h到20h.文内测量和比较了渗硼后钛合金表面的微结构、形貌、相组成等性质,研究了渗硼过程中Ti,Al,V,B等元素的扩散行为.在低温短时间渗硼时,渗硼层厚度仅0.8μm,而在高温长时间渗硼时,渗硼层厚度可达15 μm.实验证明,渗硼层由TiB和TiB2两相组成,并且它们的含量随渗硼温度提高而增加.渗硼层表面主要含TiB2,其显微硬度可达2200 HV0.01,渗硼层内表层主要含TiB,其显微硬度为1100 HV0.01.渗硼层的硬度远高于TC4钛合金的硬度.     

基于模糊理论的Ti-22Al-25Nb合金高温本构关系模型

运用Gleeble1500热模拟实验机对Ti-22Al-25Nb钛合金试样进行热模拟压缩试验,针对该合金高温变形过程时复杂的流变行为,以实验所得数据(变形温度940～1030℃,应变速率0.001～10s-1)为基础,从模糊集理论的本质特征出发,提出了一种基于模糊动态线性原理的本构模型,并与实验结果进行了对比。结果表明:基于模糊集理论建立的Ti-22Al-25Nb合金的高温本构关系模型是切实可行的,拟合程度较高,弥补了传统回归模型不能反映变形全过程的局限性,是一种有广泛应用前景的表征工程材料本构关系的便捷有效的方法。