热压烧结Fe3Al金属间化合物的微观结构与力学性能

采用机械合金化结合退火处理工艺制备了不同Al含量的Fe3Al粉体,并经真空热压烧结得到Fe3Al金属间化合物块体材料,对其烧结后的微观结构、力学性能以及Al含量的影响进行了试验研究.结果表明,该材料以有序度较低的B2结构为主,同时弥散分布着Al2O3颗粒以及少量α-Fe(Al)固溶体;Fe3Al烧结块体材料的室温力学性能较铸态有明显提高,其室温抗弯强度为1000～1400MPa,压缩屈服强度和压缩应变分别为1200～1800MPa和10%～15%,洛氏硬度为55～60HRC;Al含量的变化对其微观结构和力学性能均有一定的影响.     

Al对ZG40Cr25Ni20耐磨性的影响

对Al含量为0、1.68%,4.72%和7.10%的ZG40Cr25Ni20进行了对比磨损试验.结果表明,Al的加入可以不同程度的提高材料的耐磨性能,Al含量为7.10%时耐磨性最好,其在相同条件下的耐磨性为不含Al时的2.62倍,其次为Al含量为4.72%,其耐磨性比Al含量为1.68%时提高66.40%,试验合金的磨损机理为微观切削.     

机械合金化及真空热压制备纳米晶Fe3Al的组织及性能

采用机械合金化(MA)及热压烧结工艺制备纳米晶Fe3Al块体材料。采用X射线衍射、透射电镜、扫描电镜等对MA粉体及热压块体的相及显微组织进行分析,并对热压块体的力学性能及断口形貌进行了测试分析。结果表明:Fe72Al28混合粉在球磨过程中,Al逐渐溶入Fe中,形成Fe(Al)过饱和固溶体,纳米晶粉体的结构有序度较低。在1200℃,保温1h下真空热压烧结,Fe(Al)转变为有序的DO3-Fe3Al,同时发生晶粒长大。Fe3Al块体晶粒尺寸为40.1nm,相对密度大于96%,维氏硬度626.8 HV,三点弯曲强度985MPa;弯曲断口为脆性断口,但也呈现出一定韧性断裂特征。     

不同压力下的热压加工对含Mn块体纳米晶Fe3Al组织和性能的影响

对铝热反应熔化制备的含10wt%Mn块体纳米晶Fe3Al材料在800℃和1000℃温度下,采用不同压力进行热压加工,利用XRD研究热压加工前后纳米晶粒尺寸的变化,并测试硬度变化和压缩率。结果显示,不同温度、压力下热压加工后,晶粒尺寸变化不大;热压加工后,材料的硬度有所上升,但温度和压力对硬度影响不大;热压加工中,材料表现出较好的塑性变形,并随着热压压力的增大,材料压缩率逐渐增大,但温度对材料的压缩率影响不明显。热压加工后,块体纳米晶Fe3Al材料几何尺寸得到了增大。     

二次热压法制备SiCp/Al复合材料的耐磨性能研究

采用快速升温二次热压法制备了(10~30)SiC/Al-0.8Si-1.2Mg-0.4Cu复合材料,并研究其与钢球对磨的摩擦磨损规律。结果表明,二次热压变形法能有效抑制剧烈的界面反应,得到高致密的SiCp/Al复合材料。复合材料的摩擦因数随SiC含量增加而增大,大载荷下增幅更明显。试验条件下,SiC/Al复合材料与GCr15钢的摩擦因数在0.3~0.5之间。复合材料的磨损率开始随载荷增大而增大,载荷超过5N后,SiC含量小于15%的试样磨损率继续增大,而SiC含量大于20%的试样的磨损率则急剧减少。这是由于高SiC含量试样在大载荷下表层生成的Al2O3增强了摩擦层。在载荷7N时,30SiC/Al复合材料的磨损率只有1.14×10-3mm3/m,说明该复合材料更适宜在大载荷下应用。     

TiC/Fe基复合材料的耐磨性能研究

采用真空消失模铸造结合SHS技术制备TiC/Fe基表面复合涂层,研究了涂层的硬度及其耐磨性。在MMW-1型销盘式摩擦磨损试验机上,分别采用TiC涂层和基体材料作为试样,研究了不同载荷条件下两种材料的磨损机理。结果表明:随着载荷的增大,TiC涂层和基体材料的磨损量均增加。在不同的载荷条件下,TiC涂层的耐磨性能均优于基体材料的耐磨性能,其磨损机制主要为磨粒磨损。     

SiCp含量和尺寸对Al基复合材料摩擦学特性的影响

通过分析SiCp/Al基复合材料中第二相SiCp的含量、分布和尺寸对其性能的影响,深入地研究了微米、亚微米SiCp/Al复合材料的摩擦磨损特性,尤其是SiCp/Al复合材料磨损亚表层特性的影响.研究结果表明:复合材料的磨损是粘着磨损、微切削和剥层的共同作用,SiCp对材料粘着磨损有一定的抑制作用,且随着SiCp粒度和含量的增大,SiCp/Al基复合材料的耐磨性也随之增加;由于SiCp承担了部分载荷和表层存在着机械混合层,因此复合材料具有比其基体金属更高的耐磨性.     

Al3Ti/7075铝基复合材料磨损性能研究

研究了超声原位制备的Al3 Ti/7075铝基复合材料在不同载荷和滑动摩擦速度下的干摩擦磨损性能.采用SEM对磨损面和磨屑显微组织进行观察与分析,讨论了不同载荷下材料的磨损机制.结果表明:基体和复合材料磨损质量损失随着滑动摩擦速度和载荷的增加而增加.基体和复合材料都是从轻微磨损向严重磨损转化.当载荷为10～30N时,基...     

热氧化处理对钛合金表面耐磨性能影响的研究

为研究热氧化工艺对钛合金表面耐磨性的影响,提高钛合金的表面硬度和耐磨性能,采用热氧化处理技术在钛合金表面生成热氧化陶瓷层,借助电子探针、X衍射仪对热氧化层进行了成分和结构分析.采用MRH-3型高速滑块磨损试验机,在润滑务件下对经热氧化处理和未处理的Ti6Al4V合金耐磨性进行滑动一滚动试验.结果表明:热氧化后的Ti6Al4V合金的磨损量明显减少,该热氧化处理方法能显著增强Ti6Al4V合金的耐磨性.根据试验结果和系统分析,讨论了热氧化处理后材料的摩擦磨损机制.     

TiCNi／Fe自蔓延反应热压复合工艺及其摩擦磨损性能研究

进行了TiCNi/Fe应力缓解自蔓延反应热压复合涂层设计研究,提出了新的涂层结构设计方法.利用自蔓延反应热压技术,在铁基体表面制备了TiCNi金属陶瓷梯度涂层.研究了TiCNi/Fe金属陶瓷材料微观组织,采用球一盘式磨损试验机进行磨损试验,重点探讨了其磨损特性.结果表明:TiCNi/Fe基金属陶瓷具有优良耐磨性,在干摩擦条件下,载荷为30 N,磨损40 min,材料几乎没有质量损失,其磨损机制主要为粘着磨损、磨粒磨损和硬质相剥落.     

原位自生(TiC+TiB)/Ti6Al4V复合材料摩擦磨损性能研究

本文用原位反应法制备了不同TiC和TiB增强相含量的(TiC+TiB)/Ti6Al4V复合材料(简记为TMC),用HT-1000型摩擦磨损试验机研究了外加载荷对原位本文用原位反应法制备了不同TiC和TiB增强相含量的（TiC+TiB）/Ti6Al4V复合材料（简记为TMC）,用HT-1000型摩擦磨损试验机研究了外加载荷对原位（TiC+TiB）/Ti6Al4V复合材料干滑动摩擦磨损性能的影响,并利用扫描电镜及布鲁克三维形貌仪观察分析其磨损行为。结果显示,与Ti6Al4V基体相比,TiC+TiB增强相的生成提高了复合材料的耐磨性。对于含不同体积分数增强相的复合材料,随着外加载荷的增加,材料的磨损率和磨损深度增加,摩擦系数减小且在小范围内波动。在小负载下,磨损的表面覆盖有一些沟槽和少量磨屑;在大负载下,磨损的表面覆盖有一些浅沟槽和大量磨屑。磨损机制为磨粒磨损和氧化磨损。随着负荷增加,碎屑的尺寸增加,磨损加剧。     

OXIDATION OF PM ALLOY Al-10Ti DURING SLIDING WEAR

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DRY SLIDING WEAR OF PM Al 10Ti ALLOY

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Tribological Properties of Nanostructured Al/Al_(12)(Fe,V)_3Si Alloys

Tribological behavior of nanostructured pure Al and Al–Al12(Fe,V)3Si alloys containing 27(FVS0812) and 37(FVS1212) vol% of Al12(Fe,V)3Si precipitates was investigated. All samples were prepared using mechanical alloying followed by hot pressing. Wear tests were performed at room temperature using a pin-on-disk machine. Results showed that the presence of Al12(Fe,V)3Si precipitates increases the wear resistance of nanostructured Al, and the wear resistance increases with increasing the Al12(Fe,V)3Si content. Scanning electron microscopy images of worn surfaces and wear debris demonstrated that abrasion and adhesion are the governing wear mechanisms for the nanostructured FVS0812 alloy at 2 and 5 N normal loads, whereas for the nanostructured FVS1212 alloy, the dominant wear mechanism is abrasion at these loads. A mechanically mixed layer(MML) containing Fe and O was formed on the worn surfaces of FVS0812 and FVS1212 samples at 10 N normal load. Formation and delamination of MML controls the wear behavior of these samples at the normal load of 10 N. It is also found that the presence of Al12(Fe,V)3Si precipitates decreases the friction coefficient of nanostructured Al.     

Dry sliding wear of MA/PM Al-10Ti alloy

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Sliding wear behavior of high velocity arc sprayed Fe-Al coating

The friction and wear behavior of Fe-Al intermetallics based coating produced by high velocity are spraying technique under dry sliding at room temperature were investigated using a ball-on-disc tribotester. The effect of sliding speed on friction coefficient and wear of the coating was studied. The worn surface of the coating was analyzed by scanning electron microscope (SEM) to explore sliding friction and wear mechanism. The results show that the variations of friction coefficient can be divided into three distinct steps during the trail. Both the friction coefficient and the wear of the coating increase with increased sliding speed due to accelerated crack propagation rate and lamellar structure with poor ductility of the coating. The coating surface is subjected to alternately tensile stress and compression stress during sliding wear process, and the predominant wear mechanism of the coatings appears to be brittle fracture and delamination.     

High Temperature Oxidation and Wear Resistance of Y-modified Hot Dipping Aluminized Coating on SCH12 Steel

Microstructures,high-temperature oxidation and wear resistance of hot dipping Al-Si-Y coating on SCH12 heat resistant cast steel were investigated in this study.The aluminized coating was characterized by scanning electron microscopy(SEM),energy dispersive X-ray spectrometry(EDX)and X-ray diffraction(XRD).The results showed that the coating was composed of the Al-rich outer layer and the intermetallics inner layer.In the Al-rich layer,some Y-rich precipitates and Fe-Al-Si-Cr precipitates could be observed.The intermetallics layer presented three layers induced by the increase of Fe,Cr,Ni content and the corresponding decrease of Al,Si content.The oxidation tests were conducted in still air at 850℃for up to 100 h.After oxidation,a top oxide scale composed of mainlyα-Al2O3,Al5Y3O12 was formed on the steel surface.The intermetallics beneath the oxide scale consisted of mainly FeAl and small amount of Fe2Al5 and Cr3Si phase.The mass gain of the coated and uncoated SCH1steel is 0.45 mg/cm 2 and 0.57 mg/cm 2,respectively.The wear resistance was investigated using a high-temperature pin-on-disc tribometer at 650℃.The wear rate for the coated and uncoated steel is 0.45μm 3 /μm.N and 3.01μm 3 /μm.N,respectively.The high temperature wear tests and oxidation tests results demonstrated that the yttrium-modified aluminized specimen had significantly improved high-temperature wear resistance and equivalent oxidation resistance compared with the original SCH12 specimen.     

选区激光熔化成形Ti6Al4V合金摩擦磨损性能的各向异性

基于选区激光熔化技术制备了Ti6Al4V钛合金,研究了不同成形表面(XOY、XOZ)和不同载荷(20、40、60、80 N)对Ti6Al4V合金摩擦磨损性能的影响。通过摩擦系数(COF)结合磨损体积损失对不同成形面的摩擦磨损性能进行评估,采用光学显微镜(OM)、三维轮廓测量仪等设备对磨损轨道的形态和磨损机理进行表征。结果表明:相比XOZ面,XOY面在法向载荷为20N时其磨损体积减少了0.27×10-5 mm3,平均摩擦系数更小;而当载荷大于20N时,XOY面的磨损体积和平均摩擦系数均大于XOZ面。磨损轨道犁槽的深度和宽度随着载荷的增加而增加,犁槽呈现出明显的剥落行为,轨道处分布着块状的"粘合剂",发生着粘着磨损和氧化磨损。从摩擦系数、磨损体积、微观形态的角度定量反映出SLM成形Ti6Al4V合金的XOZ面比XOY面具备更优异的摩擦磨损性能,只有在低载荷下XOY面才表现出更加耐磨的特性。     

Casting fabrication of in situ Al3Ti-Al composites and their wear behaviors

The Al3li intermetallic reinforced pure Al, Al-13Si and Al-17Cu matrix composites were prepared by casting method. Their microstructures and dry sliding wear behaviors at room temperature and 100℃ were particularly investigated. The results indicated that the Al3Ti phases in these composites were all in flaky form. But the aspect ratio of the Al3Ti platelets decreased with the increase of Ti content in the pure AI, Al-Cu and Al-Si matrix composites, in order of effectiveness. The effect of Si on the Al3Ti morphology seemed to be greater than that of Cu. The distributions of the Al3Ti platelets were different in the different matrix composites, leading to different grain refining effects. Except for the sub-wear regime of adhesive wear, the plastic deformation induced wear was a dominant wear mechanism for all of the composites at room temperature and 100℃. Increasing the testing temperature, decreasing the Al3Ti content or the hardness of materials could enhance these two wear mechanisms, and thus increase the wear rate. The Al-Cu matrix composite had the best wear resistance, while the pure Al matrix composite showed the worst for the same Ti content. These differences or changes were attributed to the differences in materials' hardness or the strengthening effects of the Al3Ti platelets.     

Dry sliding wear behavior of Al 2219/SiCp-Gr hybrid metal matrix composites

The dry sliding wear behavior of Al 2219 alloy and Al 2219/SiCp/Gr hybrid composites are investigated under similar conditions. The composites are fabricated using the liquid metallurgy technique. The dry sliding wear test is carried out for sliding speeds up to 6 m/s and for normal loads up to 60 N using a pin on disc apparatus. It is found that the addition of SiCp and graphite reinforcements increases the wear resistance of the composites. The wear rate decreases with the increase in SiCp reinforcement content. As speed increases, the wear rate decreases initially and then increases. The wear rate increases with the increase in load. Scanning electron microscopy micrographs of the worn surface are used to predict the nature of the wear mechanism. Abrasion is the principle wear mechanism for the composites at low sliding speeds and loads. At higher loads, the wear mechanism changes to delamination.