微观组织特征对模拟海水中搅拌摩擦加工Ti-6Al-4V合金腐蚀磨损性能的影响

目的研究搅拌摩擦加工细晶Ti-6Al-4V合金在模拟海水中微观组织特征与腐蚀磨损性能的关系。方法通过控制搅拌摩擦加工工艺(200 r/min-25 mm/min和200 r/min-50 mm/min)获得具有等轴细晶组织和片层状α相组织的Ti-6Al-4V合金。使用往复磨损试验机和电化学工作站,在模拟海水中对Ti-6Al-4V合金进行腐蚀磨损实验,获得摩擦系数-时间曲线、动电位极化曲线等一系列摩擦磨损和电化学曲线。使用激光共聚焦显微镜和扫描电子显微镜对磨痕进行观察,计算磨损率,并分析磨损机制。通过计算腐蚀磨损分量研究材料损耗的主要影响因素。结果在腐蚀磨损中,因表面氧化膜被破坏,具有细晶结构的Ti-6Al-4V合金晶界面积大,腐蚀电位降低,但腐蚀电流密度小于原始试样。搅拌摩擦加工试样在腐蚀磨损实验中的摩擦系数更稳定,OCP条件下,具有细小等轴晶组织的搅拌摩擦加工Ti-6Al-4V合金的摩擦系数最低,磨损率较原始试样低20%。片层组织特征Ti-6Al-4V合金因微观力学性能各向异性而影响对磨球的行进路线,犁沟较混乱。原始样品的磨损机制主要为磨粒磨损和腐蚀磨损,搅拌摩擦加工后,样品在模拟海水中的磨损机制为磨粒磨损、分层磨损和腐蚀磨损。结论等轴细晶组织Ti-6Al-4V合金在模拟海水中表现出低的磨损率和低的摩擦系数,该组织特征具有最优的耐腐蚀磨损性能。     

添加晶粒细化剂硅对Ti-6Al-4V合金组织和性能的影响(英文)

采用真空感应凝壳熔炼工艺在石墨模中制备Ti-6Al-4V和Ti6Al4V0.5Si两种钛合金。将硅作为一种晶粒细化剂加入到Ti-6Al-4V合金中,考察添加硅对铸态和模锻态Ti-6Al-4V合金组织和性能的影响。铸态合金先在900°C下进行热模锻处理,然后分别进行两种不同的热处理。一种是将模锻样品在1050°C下保温30min,然后水淬以获得细小的层片状组织;另一种是将模锻件在1050°C下保温30min,然后再在800°C下保温30min,以获得粗大的层片状组织。Ti6-Al-4V合金中添加0.5%Si后,铸态合金的晶粒尺寸从627μm减小到337μm,其极限抗拉强度增加约25MPa。具有细小、层片状组织的Ti-6Al-4V0.5Si合金的最大极限抗拉强度为1380MPa,在Hank溶液和NaCl溶液中的腐蚀速度分别为1.35×106和5.78×104mm/a。Ti-6Al-4V合金中添加0.5%Si后,在低滑动速度下的磨损率降低50%,在高滑动速度下的磨损率降低约73%。     

Ti-6Al-4V合金激光表面合金化制备Ti_5Si_3/Ti耐磨复合材料涂层研究

利用预涂 Si粉对 Ti- 6Al- 4V合金进行激光表面合金化 ,制得以初生及共晶金属间化合物 Ti5Si3为增强相的快速凝固“原位”耐磨复合材料表面改性层 ,研究了激光表面合金化 Ti5Si3/β- Ti耐磨复合材料表面改性层的显微组织及其在干滑动磨损及二体磨料磨损条件下的耐磨性能。结果表明 :利用 Si粉对 Ti- 6Al- 4V合金进行激光表面合金化处理后 ,合金层硬度及耐磨性大幅度提高。     

Ti-6Al-4V热浸镀铝涂层干滑动磨损行为的实验研究

Ti-6Al-4V合金经热浸铝并在650℃下进行高温扩散退火处理,获得TiAl3涂层。采用销-盘式磨损试验机研究铝化后的Ti-6Al-4V合金与GCr15钢对磨的干滑动磨损行为。通过SEM、XRD、EDS和XPS等微观分析手段测试热浸镀铝涂层磨面的形貌、物相和成分,并且探讨其磨损机制。研究结果表明：随着滑动速度的增加,当滑动速度为0.75m/s时,铝化后的Ti-6Al-4V合金的磨损量先减小到最小值,然后在2.68m/s时增加到最高值,最后在4m/s时降至最低值。在不同的滑动速度下,磨损量随着载荷的增加而增加。研究发现,摩擦层结构对磨损的行为和机制有显著的影响。在4m/s时,含氧的摩擦层(TiO和TiO2)具有明显的减磨性能;相反地,在2.68m/s时,没有氧化物的摩擦层并未显示出对磨损具有保护作用。与未经热浸镀处理的Ti-6Al-4V合金相比,在不同工况下,铝化后的涂层提高了钛合金的耐磨性,尤其速度为4m/s。耐磨性得到提高是由Ti-Al涂层和摩擦氧化物层所引起的。     

TC4合金的磨损率及磨损表面层的显微组织变化

在空气和真空(10^-5Pa)条件下对TC4合金进行了系统的磨损性能测试，研究了载荷和滑动速度对TC4合金磨损率的影响。对TC4合金磨损后的表面层进行了显微组织分析。试验结果表明，空气磨损后表面层的显微组织在较低滑动速度下呈现位错的滑移带，在较高滑动速度下出现显微裂纹。真空磨损后表面层的显微组织发生细化并具有50nm～100nm尺寸，显微组织中呈现大量的位错，在较高滑动速度下有孪晶出现。     

Ti6Al4V合金干滑动磨损过程中摩擦层及摩擦氧化物的作用

目的分析Ti6Al4V合金在不同滑动速度下的干滑动磨损行为及磨损特征,研究钛合金的磨损机理,并探讨干滑动磨损过程中摩擦层及摩擦氧化物的作用。方法采用销盘式摩擦磨损试验机,对Ti6Al4V合金在不同滑动速度下进行干滑动磨损实验。采用磨损率和摩擦系数表征钛合金的磨损行为,采用SEM、EDS及XRD分析磨损表面及摩擦层的形貌及成分,采用数字显微硬度仪表征摩擦层的力学性能。结果滑动速度在0.5～4 m/s范围内变化,Ti6Al4V合金的磨损率发生显著变化,尤其是在高载条件下。0.5～1.5 m/s速度范围内,磨损率较低,2.68m/s速度下,磨损率达到最高值,4m/s速度下,磨损率达到最低值。0.75m/s速度下,粘着磨损和磨粒磨损为主要磨损机理,氧化磨损为次要磨损机理;2.68 m/s和4 m/s速度下的磨损机理分别为剥层磨损和氧化轻微磨损。2.68m/s速度下的高磨损率与硬度较低的无氧化物摩擦层对应,而4 m/s速度下的低磨损率与高硬度的多氧化物摩擦层对应。结论试验条件改变,Ti6Al4V合金的磨损行为及磨损机理发生变化。不同试验条件下的磨损行为与不同的摩擦层特征相对应,当摩擦层中包含一定量的摩擦氧化物时,这种陶瓷性的摩擦层具有比基体更高的硬度,能有效保护基体,降低磨损率。     

Ti-6Al-4V合金氮离子注入后在Tyrode’s体液中的耐蚀耐磨性能

Ti-6Al-4V合金注入氮离子后,生物相容性、抗磨损性、抗疲劳性及抗腐蚀性均有所提高,其植入人体后在体液中的耐蚀耐磨性能尤为重要,目前对此研究较少。对Ti-6Al-4V合金进行氮离子注入,并在人工模拟体液Tyrode’s溶液中进行摩擦磨损和电化学试验,研究了注氮Ti-6Al-4V合金的耐蚀耐磨性能。采用扫描电镜观察腐蚀形貌,用其自带的能谱仪分析注氮层的元素组成,采用X射线衍射仪分析注氮层的结构。结果表明:Ti-6Al-4V氮离子注入后表面形成主要由TiC,Ti及少量TiO2组成的膜层,硬度提高,在Tyrode’s溶液中的腐蚀电位升高、极化电阻增大,阳极极极化电流密度降低;在Tyrode’s溶液中摩擦后的注氮Ti-6Al-4V合金的阳极极化电流密度大于未摩擦的,极化电阻减小;Ti-6Al-4V合金氮离子注入后的摩擦系数明显降低,比磨损率减少。     

细晶粒钛合金热影响区晶粒长大规律

细晶粒钛合金经历焊接热循环后,热影响区粗晶区晶粒具有严重的长大倾向。针对TIG焊接过程,研究了显微组织为等轴状结构的细晶粒Ti-6Al-4V合金粗晶区晶粒长大规律,分析了晶粒粗化对粗晶区组织转变和接头硬度的影响。结果表明,母材晶粒细化引起的冷却过程中卢相变点变化,导致细晶粒Ti-6Al-4V合金粗晶区晶粒与普通Ti-6Al-4V合金相比具有更小的长大倾向;马氏体形核率的降低导致细晶粒Ti-6Al-4V合金粗晶区a’马氏体束在生长过程具有更强的位相性,晶界片状马氏体片层厚度和晶内马氏体板条长度随粗晶区晶粒尺寸增加明显增大;与普通Ti-6Al-4V合金相比,细晶粒Ti-6Al-4V合金粗晶区晶粒长大未引起软化问题。     

TC4合金表面TiNi/Ti2Ni改性层不同载荷滑动干摩擦性能研究

利用等离子表面合金化技术在Ti6Al4V合金表面制备了TiNi/Ti2Ni合金层,考察了合金层的表面形貌、成分分布、截面组织形貌、相结构。采用球盘磨损试验机分析了TiNi/Ti2Ni合金层在不同载荷下的滑动干摩擦学性能,并与基体进行对比。结果表明,基体和TiNi/Ti2Ni合金层磨损机制主要表现为磨粒磨损。在同一磨损条件下,TiNi/Ti2Ni合金层的摩擦系数略低于基体,耐磨性优于基体。TiNi/Ti2Ni合金层在不同载荷的摩擦系数接近,在0.29~0.32之间波动。随着载荷的增加,磨损率增加。     

快速多重旋转碾压诱导Ti-6Al-4V表面纳米晶及性能研究

目的 使Ti-6Al-4V能更好地应用于海洋领域.方法 采用快速多重旋转碾压技术(FMRR)对Ti-6Al-4V表面进行冷变形处理,研究其力学性能.然后,对其进行低温等离子渗氮,渗氮温度为550℃,保温时间4 h.利用高分辨透射电子显微镜(HRTEM)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)和电子显微硬度计等测试设备,对FMRR处理后的Ti-6Al-4V表层组织结构和性能以及等离子渗氮处理后表层组织结构进行表征.结果 经15、30、45 min的FMRR处理后,Ti-6Al-4V表层晶粒细化并获得了纳米结构,对应的平均晶粒尺寸为65～90、45～70和20～40 nm.此时,晶界明显增多,局部存在孪晶、小角度晶界和高密度位错等结构缺陷,电子衍射环连续.同时,Ti-6Al-4V表层结构未出现新相,晶粒细化导致衍射峰略有变宽,也提高了Ti-6Al-4V表面的显微硬度,显微硬度为325～453HV,比处理前提高了约41％.FMRR预处理的试样经过低温等离子渗氮后,基体表面的渗氮层主要包括白色化合物层和过渡层两个区域.结论 FMRR处理为后续低温渗氮提供了能量条件和结构条件,提高了渗氮的速度,最终的渗氮层厚度约为100μm.     

钛合金表面激光熔覆TiB2-TiC/Ni复合涂层的真空摩擦磨损性能

采用激光熔覆技术在TC4钛合金表面制备以反应合成TiB2和TiC颗粒为增强相的Ni基复合涂层,利用УТИТВ-100型销-盘摩擦磨损试验机研究了激光熔覆层在真空(10-5Pa)中的干滑动摩擦磨损性能,利用光学显微镜和扫描电子显微镜观察了摩擦偶件的磨损表面形貌,讨论了激光熔覆层的磨损机制。结果表明,激光熔覆层的摩擦系数在0.25～0.5之间,明显低于TC4合金的摩擦系数(0.45～0.8),磨损体积约为TC4合金的40%。随法向载荷和滑动速度的增加,激光熔覆层的磨损体积增加,激光熔覆层的磨损机制主要为粘着磨损和粘附转移物引起的磨粒磨损。     

Effect of Microstructural Variation on Dry Sliding Wear Behavior of Ti-6Al-4V Alloy

The present article evaluates the influence of independent control factors such as microstructural variation, normal load, sliding velocity, and test duration on dry sliding wear behavior of Ti-6Al-4V alloy at room temperature using a statistical approach. Ti-6Al-4V alloy has been heat treated in a controlled manner in order to produce different microstructural features (i.e., lamellar, bimodal, and equiaxed). Lamellar microstructure is found to be harder than bimodal microstructure followed by equiaxed microstructure in Ti-6Al-4V alloy. Dry sliding wear tests have been carried out using a multiple Tribo tester following a well planned experimental schedule based on Taguchi’s L₉ orthogonal array design. Dry sliding wear behavior of Ti-6Al-4V alloy consisting of various microstructural features is related to their hardness values. Results indicated that lamellar microstructure has the lowest sliding wear resistance followed by bimodal and equiaxed microstructure. With the help of signal-to-noise ratios, optimal combination of control factors to minimize the dry sliding wear in Ti-6Al-4V alloy has been determined. Normal load is the most significant control factor influencing the dry sliding wear behavior of investigated Ti-6Al-4V alloy followed by sliding velocity, test duration, and microstructural variation. Normal load has greater static influence of 27.02%, sliding velocity has an influence of 18.07%, test duration has an influence of 12.71%, and microstructural variation has an influence of 10.55% on weight loss of Ti-6Al-4V alloy due to wear having R ² = 0.89. Two wear mechanisms have been identified: oxidative wear occurs at the lowest sliding velocity and delamination wear occurs at the highest sliding velocity. Optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and Rockwell hardness measurements have been used to characterize the microstructures in order to correlate the results obtained.     

Ti-6Al-4V和Monel K500合金在海水环境中与316不锈钢对磨时的腐蚀磨损性能(英文)

研究Ti-6Al-4V和Monel K500合金在海水和纯水环境下的腐蚀磨损性能,对偶材料为316不锈钢,实验装置为环-块摩擦磨损试验机。研究结果表明,Ti-6Al-4V和Monel K500合金在海水中的摩擦因数明显小于在纯水中的摩擦因数,在海水中的磨损量明显大于纯水中的磨损量,这主要是由于摩擦作用破坏了金属表面的钝化膜,增加了摩蚀速度。磨损和腐蚀产生交互作用,交互作用量随着腐蚀速度的加快而增加。当和Monel K500配副时,316不锈钢的磨损严重,而和Ti-6Al-4V配副时磨损相对较小。     

A comparative study: The effect of surface treatments on the tribological properties of Ti-6Al-4V alloy

The effect of different surface treatments on the wear resistance of Ti-6Al-4V alloy has been investigated. For this purpose, plasma nitriding treatment was performed in a gas mixture 75% N₂-25% Ar, for 1 h treatment time and at 750 °C. The thin films were deposited using CFUMBS technique. The results showed that more surface roughness was obtained for nitrided specimens compared with thin film deposited specimens. It was also observed that both surface treatments improved the wear resistance of Ti-6Al-4V alloy. It was determined that plasma nitrided specimens exhibited excellent wear resistance compared with thin film deposited ones when applied load increased. Similar results were obtained from surface hardness measurements, and it was observed that load bearing capacity increased after plasma nitriding. The corrosion resistance of both surface treatments showed similar properties.     

Wear Resistance Enhancement of Ti-6Al-4 V Alloy by Applying Zr-Modified Silicide Coatings

Zr-modified silicide coatings were prepared on Ti-6Al-4 V alloy by pack cementation process to enhance its wear resistance. The microstructure and wear properties of the substrate and the coatings were comparatively investigated using GCr15 and Al₂O₃ as the counterparts under different sliding loads. The obtained Zr-modified silicide coating had a multilayer structure, consisting of a thick (Ti,X)Si₂ (X represents Al, Zr and V elements) outer layer, a TiSi middle layer and a Ti₅Si₄ + Ti₅Si₃ inner layer. The micro-hardness of the coating was much higher than the substrate and displayed a decrease tendency from the coating surface to the interior. Sliding against either GCr15 or Al₂O₃ balls, the coatings showed superior anti-friction property to the Ti-6Al-4 V alloy, as confirmed by its much lower wear rate under each employed sliding condition.     

Dry sliding wear of Ti-6Al-4V alloy in air and vacuum

1　INTRODUCTIONTitaniumanditsalloysareidealmaterialsforaerospaceandspaceindustriesbecauseoftheirhighspecificstrengthandexcellentcorrosionresistance[1] .Thevacuumenvironmentmustbeconsideredinspaceapplicationswherewearresistanceisrequired .Theabsorption ,stainsandoxidesmaybetotallyorpar tiallyremovedfromthesolidsurfaceinvacuum[2 ] .Thus ,arelativelyclearsurfacecanbeformed ,whichmightresultinanadhesionorevencoldweldingduetothestrongattractiveforcesbetweenmoleculesofthecontactingsurfaces[3] .…     

钛合金Ti-6Al-4V的磨损失效及其表面耐磨处理技术

Ti-6Al-4V钛合金具有比强度高、耐腐蚀性强、高温力学性能稳定、生物相容性好等一系列优点．是使用最广泛的钛合金之一．但其耐磨性较差。本文分析了Ti-6Al-4V钛合金不同形式磨损失效的起因,对其常用的表面耐磨处理技术进行了评述。研究表明。采用表面工程技术如电镀、化学镀、热喷涂、化学热处理、气相沉积、离子注入、表面氧化处理、激光表面合金化等对其进行处理。是提高其耐磨性的有效手段。同时讨论了Ti-6Al-4V钛合金各种表面耐磨处理技术的特性和适应性。并指出了进一步研究的方向。     

Influence of spark plasma sintering on microstructure and wear behaviour of Ti-6Al-4V reinforced with nanosized TiN

Ti-6Al-4V/TiN composites were successfully consolidated by spark plasma sintering (SPS). TiN addition to Ti-6Al-4V was varied from 1% to 5% (volume fraction). The effect of TiN addition on the densification, microstructure, microhardness and wear behaviour of Ti-6Al-4V was studied. Experimental results showed reduction in sintered density of the compacts from 99% to 97% with increase in TiN content. However, an increase in microhardness value was recorded from HV_0.1 389 to HV_0.1 488. X-ray diffraction (XRD) analysis showed that the intensity of diffraction peaks of TiN phase in the composites increased also with formation of small amount of secondary Ti₂N phase. SEM analysis of SPS sintered nanocomposites possessed a refinement of α/β phase microstructure in Ti-6Al-4V with the presence of uniformly dispersed TiN particles. The worn surface of the composite showed improved abrasive wear resistance with non-continuous grooves as compared to the sintered Ti-6Al-4V without TiN addition.