Wear behaviors of an (TiB + TiC)/Ti composite coating fabricated on Ti6Al4V by laser cladding

A titanium-based composite coating reinforced by in situ synthesized TiB whiskers and TiC particles was successfully fabricated on Ti6Al4V by laser cladding. The coating is mainly composed of α-Ti cellular dendrites and a eutectic in which a large number of needle-shaped TiB whiskers and a few equiaxial TiC particles are uniformly embedded. The wear resistance of the coating is significantly superior to that of Ti6Al4V under the dry sliding wear condition at room temperature.     

Al/Ti摩尔比对(CrTiAl)N硬质膜相结构和硬度的影响

采用多弧离子镀技术,设计沉积工艺和调整阴极弧源靶组合以及对应的弧源电流,制备出以CrN为基形貌和厚度相同、A1/Ti摩尔比不同的系列(CrTiAl)N硬质膜.测试膜的成分、组织形貌、相组成和表面硬度,研究了A1/Ti摩尔比对其相结构和硬度的影响.结果 表明:不同A1/Ti摩尔比的(CrTiAl)N膜其相组成相同,都呈现...     

Ti_2AlC-TiB_2对TiAl基复合材料组织及力学性能的影响

以Ti、Al和B4C为原料,采用真空电弧熔炼的方法制备了含Ti_2AlC-TiB_2增强相的TiAl基复合材料;分析了添加不同含量的Ti_2AlC-TiB_2对复合材料的物相组成、组织结构及力学性能的影响,并探讨了微观组织结构的形成机制。结果表明:Ti_2AlC-TiB_2/TiAl复合材料主要由TiAl、Ti3Al、TiB_2和Ti_2AlC等物相组成,TiB_2和Ti_2AlC分布在层片状的TiAl+Ti3Al基体中;随着原料中B4C含量的增多,复合材料组织中Ti_2AlC-TiB_2含量增多,且TiAl基体的晶粒被明显细化,TiB_2和Ti_2AlC分布于基体晶界或晶内。Ti_2AlC主要为层片状和板条状,尺寸5~15μm,而TiB_2颗粒形态与其含量有关,当Ti_2AlC-TiB_2含量小于20wt%时,TiB_2颗粒呈针棒状,尺寸为0.5~5μm,当Ti_2AlC-TiB_2含量增加到30wt%时,TiB_2颗粒主要呈块状,尺寸为5~20μm。Ti_2AlC由TiC与Ti-Al熔体发生包晶反应生成,Ti_2AlC和TiB_2的形成提高了Ti_2AlC-TiB_2/TiAl复合材料的硬度、塑性和抗压强度。当4Ti+Al+B4C的加入量为10wt%时,复合材料的变形量比纯TiAl提高14%,而抗压强度达到最高值1 591 MPa。Ti_2AlC和TiB_2通过裂纹偏转、颗粒钉扎、拔出等机制对Ti_2AlC-TiB_2/TiAl复合材料起到增强增塑的作用。     

316H堆焊UNS N10003合金参数优化、组织和硬度的研究

研究异种合金焊接可以降低熔盐堆结构材料的成本并确保其安全性,本文采用钨极氩弧焊(GTAW)工艺,在316H不锈钢表面堆焊一层耐高温熔盐腐蚀的UNS N10003合金,优化了焊接工艺参数,通过光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、维氏硬度计等研究了堆焊层及界面的形貌、组织和硬度,为进一步研究多层、多道堆焊提供理论依据。研究结果表明:当电流一定时,稀释率随送丝速度的增加而减小,堆焊层高度随送丝速度的增加而增加,当送丝速度一定时,改变电流大小,堆焊层高度的变化范围为0.2~0.5 mm。堆焊层界面处可以细分为对流混合区(WM)、非对流混合区(UZ)和热影响基体区(BM)。堆焊层主要为奥氏体组织,在WM区有大量富Mo的M2C碳化物析出,UZ区的析出相主要是δ铁素体;316H基体区和WM区硬度分别为(160±10)HV和(202±11)HV,在γ基体的枝晶界上分布着尺寸细小的骨架状碳化物导致WM区硬度升高。     

钛合金表面氩弧熔覆原位合成TiB_2-TiN显微组织与形成机理

以BN和Ni60A合金粉末作为预置涂层,采用氩弧热源在Ti6Al4V合金表面原位合成陶瓷颗粒复合涂层。经过热力学计算和扫描电子显微镜线扫描分析,利用X射线衍射仪进行涂层物相分析,确定陶瓷颗粒为TiB2和TiN。利用扫描电子显微镜观察微观组织形貌,并探讨TiB2-TiN颗粒的形成机理。实验结果表明,采用适宜的熔覆材料合金粉末成分和熔覆工艺参数,可以获得TiB2-TiN颗粒复合涂层,TiB2形态呈棒状和细条状,TiN形态呈颗粒状。颗粒尺寸细小,分布均匀,且与基体冶金结合。复合涂层的显微组织沿层深方向分为熔覆区、结合区和热影响区。     

Reconstruction of three-dimensional microstructures of TiB whiskers in powder processed Ti–6Al–4V–1B alloys

Visualization of three-dimensional (3D) microstructure is useful for understanding microstructural geometry. In this contribution, 3D microstructures of TiB whiskers in two powder metallurgy processed Ti–6Al–4V–1B alloys are reconstructed and visualized using large-area high-resolution montage serial sections and digital image processing to study the effects of processing route on the morphology and anisotropy of the TiB phase. The microstructures consisted of eutectic TiB in Ti-64 and are free from coarse primary phase TiB. The eutectic TiB phase has whisker morphology in both the compacted and compacted plus extruded conditions. The orientations of TiB whiskers are uniformly random in the compacted condition and highly aligned anisotropic in the extruded condition. The spatial distributions of TiB are uniform in both cases without any clustering. The large volumes of reconstructed 3D microstructures are useful for incorporation into finite element-based computations.     

A novel spark plasma sintering route to process high-strength Ti–4Al–2Fe/TiB nano-composite

Ti–4Al–2Fe alloy and Ti–4Al–2Fe/TiB nano-composite were processed by a novel spark plasma sintering route. KBF4 was used as an alternative and inexpensive boron precursor to form TiB reinforcement in situ during sintering. Fe was used as an alternative to vanadium to make the (α?+?β) Ti matrix. The processed Ti–4Al–2Fe alloy exhibited excellent mechanical properties (CS?=?1798 MPa). The TiB whiskers were distributed homogeneously and were fine (widths 130?nm and lengths from 100?nm to 3?µm). No residual TiB2 was found in the composite, in contrast with other methods. The TiB homogenised and refined the microstructure, while the hardness (710?HV), compressive strength (2414?MPa) and elastic modulus (140?GPa) all increased significantly when compared to the unreinforced alloy.     

Microstructure of in-situ Synthesized (TiB+TiC)/Ti Composites Prepared by Hot-pressing

In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning c     

Al含量对Ti1-XAlXN涂层组织结构的影响

通过不同Al含量的Ti—Al粉末冶金靶．采用多弧离子镀技术制备了Ti1-xAlxN涂层。用SEM、XRD、GAXRD以及XTEM等手段研究了Al元素对涂层组织结构的影响。研究表明，TiAlN涂层呈柱状多晶组织，(Ti，Al)N为涂层的主要组成相；随着Al含量的增加。涂层中的(Ti，Al)N相减少，且其晶格常数降低。     

埋弧堆焊WC颗粒增强复合层的工艺及性能

目的针对传统钢材硬度低、不耐磨损的问题,选用WC颗粒来增强传统钢材性能,研究不同工艺对WC颗粒增强钢基材料的影响。方法采用埋弧焊方法,将含有WC颗粒的药芯焊丝在钢板表面进行堆焊,采用SVS3020显微镜、光学显微镜和显微硬度计对焊缝的显微组织进行观察与分析。结果随着焊接电流、电压的增大,焊缝成形逐渐完好,无焊缝缺陷,焊接速度增大,焊缝有夹渣缺陷产生;焊缝硬度随着电流、速度的提升而增大,但随电压的提升而下降。结论埋弧焊焊接选用350 A电流、32 V电压和20 m/s速度成形的焊缝质量最佳,基体的稀释作用对堆焊合金层的显微硬度也有明显影响。     

Ti6Al4V钛合金表面Ta2O5/Ta2O5-Ti/Ti多涂层的制备与性能研究

采用磁控溅射技术在Ti6Al4V钛合金表面制备了Ta_2O_5/Ta_2O_5-Ti/Ti多层涂层;利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱仪 (XPS),分析了涂层的微观结构、物性组成和化学价态;通过划痕仪、纳米压痕仪、摩擦磨损试验机和电化学工作站,检测了涂层的结合强度、力学性能、摩擦系数和耐腐蚀性。研究结果表明,Ta_2O_5/Ta_2O_5-Ti/Ti多层涂层表面由峰型颗粒组成,粒径大小均匀,涂层结构致密。与Ti6Al4V相比,Ta_2O_5/Ta_2O_5-Ti/Ti多层涂层试样具有较小的摩擦系数,较高的腐蚀电位和较小的腐蚀电流密度,表现出良好的耐磨和耐腐蚀性能,能对Ti6Al4V合金植入材料起到较好的保护作用。     

射频反应溅射(Al,Ti)N涂层的微结构与力学性能

采用Al-Ti镶嵌复合靶在不同氮分压下制备了一系列(Al,Ti)N涂层,并采用EDS,AFM,XRD,TEM和微力学探针表征了涂层的沉积速率、化学成分、微结构和力学性能,研究了氮分压对涂层的影响.结果表明,氮分压对(Al,Ti)N涂层影响显著:合适的氮分压可以得到化学计量比的(Al,Ti)N涂层,涂层为单相组织,并呈现(111)择优取向,最高硬度和弹性模量分别达到36.9GPa和476GPa.过低的氮分压不但会造成涂层贫氮,而且涂层中的Al含量偏低,硬度不高.氮分压过高,由于存在"靶中毒"现象,尽管涂层的成分无明显变化,但会大大降低其沉积速率,并使涂层形成纳米晶或非晶态结构,涂层的硬度也较低.     

热处理对网状结构TiB_W/Ti60复合材料组织与性能的影响

使用大尺寸球形Ti60钛合金粉与细小TiB2粉,通过低能球磨与反应热压烧结,成功制备了增强相呈网状分布的TiB晶须增强Ti60合金基(TiB_W/Ti60)复合材料。对TiB_W/Ti60复合材料进行热处理,以改善其组织结构与力学性能。结果表明:随着固溶温度的升高,TiB_W/Ti60复合材料基体中初生α相(密排六方相)含量减少,相应地转变β组织(α′(马氏体)+残留β相(体心立方相))含量增加,TiB_W/Ti60复合材料的抗拉强度升高,塑性降低;经过1 100℃/1h固溶处理之后,TiB_W/Ti60复合材料的室温抗拉强度为1 470 MPa,延伸率为1.9%。经过时效处理后,转变β组织中的α′相分解成细小α+β相。经过1 100℃/1h固溶+600℃/8h时效处理后TiB_W/Ti60复合材料的硬度达到HV538,抗拉强度达到1 552 MPa,延伸率为1.5%,经过1 000℃/1h固溶+600℃/8h时效处理,其抗拉强度达到1 460 MPa,延伸率为2.2%。     

Al含量对(Ti,Al)N涂层结构性能的影响

(Ti，A1)N是20世纪80年代末期在TiN基础上发展起来的一种新型多元涂层材料。由于加入Al元素，(Ti，Al)N不但硬度、耐磨性优于TiN，而且大大改善了涂层的抗高温氧化性能。综述了Al元素在(Ti，Al)N涂层中的作用机理，以及Al含量对(Ti，Al)N涂层的晶体结构、抗高温氧化、硬度和耐磨性的影响。指出当Ti和Al的比例近似为1：1时，(Ti，Al)N涂层将获得优越的综合使用性能。     

Three-dimensional microstructural characterization of discontinuously reinforced Ti64–TiB composites produced via blended elemental powder metallurgy

Three-dimensional (3D) microstructures of TiB reinforcement in two discontinuously reinforced Ti–6Al–4V (Ti64) alloy composites produced via blended elemental (BE) powder metallurgy are reconstructed from large-area high-resolution optical montage serial sections. The TiB phase in both composites shows whisker morphology with roughly hexagonal cross-sections, a unimodal size distribution, and uniform random morphological orientations. The TiB whiskers in these composites are significantly coarser compared to similar materials produced via pre-alloyed powder metallurgy but did not contain coarse primary TiB particles.     

Tribological Properties of Mo-N Hard Coatings on Ti6Al4V by Double Glow Discharge Technique

Mo-N hard coatings on Ti6Al4V were formed using double glow discharge technique. The fundamental coating properties, such as the phase, hardness and elastic modulus were investigated. The tribological performances of the coatings in dry wear condition were studied by means of ball-on-disc wear machine. The experimental results showed that the thickness of the Mo-N hard coating was about 10 µm. The coating was single fcc γ-Mo2N phase with (200) preferred orientation. The hardness and the elastic modulus of the coating was 13.80 GPa and 261.65 GPa respectively. The surface treatment enhanced the hardness and elastic modulus of the surface of Ti6Al4V base greatly. With GCr15 slider ball, the friction coefficient of the Mo-N hard coating was in the range of 0.56~0.65 at the steady state. Though the coating did not show friction reducing effect, it improved the wear resistance of Ti6Al4V greatly.     

Ti6Al4V合金激光原位合成自润滑复合涂层高温摩擦学性能

为提高Ti6Al4V合金的高温摩擦学性能,采用激光熔覆技术在其表面原位合成多相混杂金属基高温自润滑耐磨复合涂层,熔覆粉末的成分为Ni60-16.8%TiC-23.2%WS_2(质量分数,下同),系统地研究复合涂层的显微组织、物相结构及其在20,300,600,800℃下的摩擦学性能和相关磨损机理。结果表明:复合涂层的显微硬度(701.88HV_0.5)约为基体(350 HV_0.5)的2倍;由于原位合成固体润滑相(Ti_2SC/TiS/NiS/TiO/TiO_2/NiCr_2O_4/Cr_2O_3)和硬质相(W,Ti)C_1-x/TiC/Cr_7C_3的协同作用,复合涂层的耐磨减摩性能明显优于基体。随着温度升高,涂层和基体的摩擦因数和磨损率均呈下降趋势,在800℃时复合涂层和基体的摩擦因数分别为0.32和0.43,磨损率分别为1.80×10^-4,2.92×10^-5mm/Nm。在800℃下塑性变形、分层和氧化磨损为基体主要磨损机理,复合涂层以氧化磨损和轻微的黏着磨损为主。     

In situ synthesis of TiB whisker reinforcements in the joints of Al2O3/TC4 during brazing

Al₂O₃ ceramic has been successfully joined to Ti-6Al-4V alloy with Ag-Cu-Ti-B mixed powder. The TiB whiskers in the brazing layer were in situ synthesized during brazing. The effects of B content in reactant on the phase composition, microstructure and shear strength of the joints were investigated using SEM, EDS, and shear test. Results indicate that B content in the filler has a great impact upon the microstructure of the joints via exerting an influence on the volume fraction of in situ synthesized TiB whiskers. When the TiB content is 40 vol.%, the shear strength reaches the maximum value of 77.9 MPa. The higher content of TiB (≥40 vol.%) depresses the shear strength of the joints due to the interfacial thermal stress cannot be relaxed. Reaction phases (Ti₃Cu₂AlO, Ti₂Cu, Ti₂(Cu, Al), Ti(Cu, Al) and Ti₃Al) appear in the joint, moreover, as the volume fraction of TiB increase, Ag (s.s) and Ti(Cu, Al) distribute more uniform and fine in the brazing layer, as well as TiB whiskers mainly distribute in them. Eventually, Ti₃Cu₂AlO, TiB and TiB₂ firstly generate based on the thermodynamic analysis, and in excessive Ti circumstances, TiB whiskers remain in the brazing alloy.     

Laser surface coating of Mo–WC metal matrix composite on Ti6Al4V alloy

Laser surface alloying of Mo, WC and Mo–WC powders on the surface of Ti6Al4V alloys using a 2 kW Nd-YAG laser was performed. The dilution effect upon the microstructure, microhardness and wear resistance of the surface metal matrix composite (MMC) coating was investigated. With a constant thickness of pre-placed powder, the dilution levels of the alloyed layers were found to increase with the incident laser power. The fabricated surface MMC layer was metallurgically bonded to the Ti6Al4V substrate. The microhardness of the fabricated surface layer was found to be inversely proportional to the dilution level. The EDAX and XRD spectra results show that new intermetallic compounds and alloy phases were formed in the MMC layer. With the existence of Mo content in the pre-placed powder, the β-phase of Ti in the MMC coating can be retained at the quenching process. With increasing weight percentage content of WC particles in the Mo–WC pre-pasted powder, the microhardness and sliding wear resistance of the laser surface coating were increased by 87% and 150 times, respectively, as compared with the Ti6Al4V alloy. The surface friction of the laser-fabricated MMC coatings was also decreased as compared with the worn Ti6Al4V substrate.     

中间层锌箔对铝-钛异种接头微观组织和力学性能的影响

本文旨在通过改善焊接工艺,提高铝-钛接头性能,扩大铝-钛复合件的应用范围.通过在铝-钛熔钎焊接工艺中添加锌箔,探讨了中间层锌箔对铝-钛接头微观组织和力学性能的影响.采用TIG焊机对铝/钛异种金属板材进行熔钎焊接实验,利用金相显微镜、扫描电镜、能谱仪、维氏硬度计和电子拉伸机对铝/钛接头的微观组织和机械性能进行分析.研究发...