固溶处理对TiB2/7050Al复合材料组织与性能的影响

研究了固溶处理对TiB₂/7050Al复合材料组织与性能的影响规律。结果表明,TiB₂/7050Al复合材料内的可溶性第二相主要为MgZn₂(η相)、AlZnMgCu(T相)和Al₂CuMg(S相)。η相在470℃已完全溶解,T相在476℃开始溶解,S相在491℃下可完全溶解。随固溶温度的升高,复合材料的强度整体呈上升趋势,但伸长率先增加后降低。在480℃固溶时,复合材料同时具备高强度和高塑性,其屈服强度、抗拉强度和伸长率分别为658 MPa、719 MPa和11.3%;继续升高固溶温度至490℃,虽然可使铝基体内残余S相完全溶解,但也使基体再结晶晶粒异常长大,降低了复合材料的塑性。     

原位TiB2增强铝基复合材料的时效行为及性能演变

通过对比原位TiB₂颗粒增强铝基复合材料和基体合金的时效行为,研究了TiB₂颗粒对时效行为的影响以及颗粒促进时效沉淀的机制。此外,还研究了时效过程中TiB₂/Al-4.5Cu复合材料和基体合金的拉伸性能和硬度的变化。结果表明,TiB₂颗粒加速了复合材料的时效过程,同时TiB₂颗粒附近的高密度位错导致了Al₂Cu相的不均匀析出。相较于基体合金,TiB₂/Al-4.5Cu复合材料的峰时效时间由20 h缩短至8 h。复合材料力学性能随时效时间的变化可以分为2个阶段,这与Al₂Cu析出相的变化具有良好的一致性。复合材料的屈服强度比时效前提高了24%,比时效的基体合金提高了82%。     

Al2O3/TiB2/Al复合材料的微观结构和高温力学性能

以细雾化铝粉和TiB₂颗粒为原料,通过粉末冶金和热轧制制备微米TiB₂和纳米Al₂O₃颗粒增强铝基复合材料。室温时,由于TiB₂和Al₂O₃的综合强化作用,Al₂O₃/TiB₂/Al复合材料的屈服强度和抗拉强度分别为258.7 MPa和279.3 MPa,测试温度升至350℃时,TiB₂颗粒的增强效果显著减弱,原位纳米Al₂O₃颗粒与位错的交互作用使得复合材料的屈服强度和抗拉强度达到98.2MPa和122.5 MPa。经350℃退火1000 h后,由于纳米Al₂O₃对晶界的钉扎作用抑制晶粒长大,强度和硬度未发生显著的降低。     

TiB2/Al-Si-Mg-Er复合材料的组织与性能

采用重熔稀释法制备了Al-7Si-0.5Mg-0.1Er和0.5TiB₂/Al-7Si-0.5Mg-0.1Er合金,研究了TiB₂颗粒增强Al-Si-Mg-Er复合材料的组织性能。结果表明,复合材料铸态组织主要由α-Al基体、共晶Si相和TiB₂颗粒组成。TiB₂粒子的加入使Al-7Si-0.5Mg-0.1Er合金二次枝晶间距减小了7.1 μm。抗拉强度达到217.53 MPa,较Al-7Si-0.5Mg-0.1Er合金提升了12.1 %。TiB₂/Al-Si-Mg-Er复合材料的最优T6热处理工艺为530 ℃×12 h固溶+160 ℃×7 h时效,经该工艺处理后,TiB₂/Al-Si-Mg-Er复合材料抗拉强度达到319.49 MPa,相比热处理前提高了46.9%,相比Al-7Si-0.5Mg-0.1Er合金提高了5.9%;屈服强度达到266.75 MPa,相比热处理前提高了106.4%,相比Al-7Si-0.5Mg-0.1Er合金提高了14.9%。复合材料抗拉强度的提升主要源于TiB₂颗粒加入后产生的晶粒细化、变质和热处理强化。     

纯铜表面氩弧熔覆TiB2/Ni复合涂层组织及耐磨性能

通过氩弧熔覆技术在纯铜表面制备TiB₂增强 Ni 基复合涂层,以改善其耐磨性能. 将钛粉、硼粉和镍粉在球磨机中充分混合,采用氩弧熔覆技术将纯铜表面预置粉末熔化制备出陶瓷颗粒增强镍基熔覆层. 采用X射线衍射仪、扫描电子显微镜、透射电子显微镜分析涂层的物相及涂层中陶瓷颗粒相的组成、分布及结构,利用显微硬度仪和摩擦磨损试验机测试涂层的显微硬度和耐磨性能. 结果表明,熔覆层物相主要包括γ(Ni, Cu)和TiB₂;陶瓷颗粒增强相弥散分布于熔覆层中,其中颗粒相TiB₂以六边形存在,熔覆层内部与基体界面处均无缺陷产生;熔覆涂层具有较高的显微硬度,当(Ti+B)质量分数为10%时,涂层显微硬度高达781.3 HV,与纯铜基体对比,熔覆层显微硬度提高约11.7倍;在相同磨损条件下,随(Ti+B)质量分数的增加,熔覆涂层的摩擦系数及磨损失重先减小后增大;氩弧熔覆原位自生TiB₂陶瓷颗粒增强镍基熔覆层可显著提高纯铜表面的耐磨性能.     

Ti6Al4V合金表面氩弧熔覆原位合成TiC-TiB2增强钛基复合涂层组织与耐磨性

以B4C和Ni60A粉末为预涂材料,采用氩弧熔覆技术,在Ti6Al4V合金表面原位合成TiC与TiB₂增强相增强钛基复合材料涂层.运用XRD,SEM等分析手段研究了复合涂层的显微组织,利用显微硬度仪测试了复合涂层的显微硬度并用磨损试验机分析了其在室温干滑动磨损条件下的耐磨性能.结果表明,熔覆层组织主要由TiC和TiB₂组成,TiC颗粒和TiB₂颗粒弥散分布在基体上,TiC颗粒的尺寸为2~3μm,而呈长条状的TiB₂颗粒尺寸为3~5μm.显微硬度和耐磨性测试结果表明,该复合涂层显微维氏硬度高达1200MPa左右,复合涂层的耐磨性能比Ti6Al4V基体提高约20倍.     

Sc元素对激光选区熔化TiB2/AlSi10Mg复合材料组织和性能的影响

采用稀土元素Sc对激光选区熔化TiB₂/AlSi10Mg复合材料进行变质处理,借助场发射扫描电镜、电子探针显微分析仪、显微硬度计以及电子万能试验机等,分别研究了添加Sc元素和固溶时效热处理对复合材料显微组织、密度和力学性能的影响。结果表明:与TiB₂/AlSi10Mg复合材料相比,Sc元素的加入可以进一步细化Al-Si共晶,产生细晶强化和弥散强化作用,TiB₂/AlSi10MgSc复合材料的抗拉强度和显微硬度分别提升了56.7 MPa (14.4%) 和15.3 HV0.1 (11.3%)。激光选区熔化TiB₂/AlSi10MgSc复合材料的硬度和强度随着固溶温度升高而逐渐降低,但伸长率得到明显改善。     

超音速火焰喷涂TiB2-40Ni涂层的组织和耐磨性

通过超音速火焰喷涂技术在Q235钢基体表面喷涂TiB₂-40Ni涂层,并对涂层的组织结构、硬度值和耐磨性进行了研究。结果表明,涂层组织致密,孔隙率为0.474%,硬度值为408±40.5 HV0.3。涂层主要由TiB₂和Ni构成。经磨粒磨损试验,TiB₂-40Ni涂层的耐磨损性能良好,磨损量为2.21±0.11 mg。     

原位自生TiB2/7050复合材料的高周疲劳断裂机制

TiB₂/7050铝基复合材料在航空发动机等领域具有重要的应用前景。本文研究了TiB₂颗粒质量分数为4%的原位自生7050铝基复合材料在T6热处理状态下的室温高周疲劳性能,利用扫描电子显微镜对复合材料的疲劳断裂机制进行分析。结果表明:在应力比R=?1、指定寿命为3×107周次时,TiB₂/7050铝基复合材料的疲劳强度为211.9 MPa,高于7050铝合金的疲劳强度;疲劳裂纹萌生源主要分布在近样品表面的夹杂、大尺寸的TiB₂颗粒及显微孔洞等区域;疲劳裂纹的扩展在遇到TiB₂颗粒带时,疲劳条带的宽度会明显减小,即TiB₂颗粒提高了复合材料的抗疲劳裂纹扩展能力,使得复合材料具有高的疲劳寿命。     

7050超高强铝合金的强韧化工艺研究

对7050铝合金不同温度进行固溶处理,研究了固溶温度对显微组织、力学性能以及耐磨性能的影响规律。结果表明,不同固溶温度条件下,7050铝合金的晶粒尺寸、第二相数量、力学性能以及耐摩擦性具有较大差异。当固溶温度较低时,基体晶粒粗大,第二相数量较少,同时力学性能和耐磨性较低。在一定温度范围内,随着固溶温度的提高,基体晶粒发生细化,第二相数量逐渐增多,同时力学性能及耐磨性能逐渐提高。当固溶温度为400℃时,晶粒发生明显细化,第二相数量最多,且力学性能及耐磨性能最佳。当固溶温度为450℃时,晶粒粗化,力学性能及耐磨性降低。     

Selective Laser Melting of In Situ TiB/Ti6Al4V Composites: Formability,Microstructure Evolution and Mechanical Performance

In the present study, a series of in situ TiB/Ti6Al4V composites were fabricated using selective laser melting. The formability, microstructure evolution and mechanical properties of the as-built samples added with different contents of TiB_2 were studied. It is found that the densification level is related to both the content of TiB_2 and laser energy density. The added TiB_2 reinforcement particle can spontaneously react with titanium and then form the TiB phase. The needle-like TiB phase tends to transform into dot-like particles with the decrease in energy density. Additionally, with the increase in TiB_2 content, the TiB phase is coarsened due to the increased nucleation rate and more reactions. The grain morphology is found to largely depend on the translational speed of solid–fluid interface determined by the temperature gradient and cooling rate. Also, the microhardness of the as-built TiB/Ti6Al4V composites is obviously improved. More interestingly, as the energy density increases, the microhardness of the as-built TiB/Ti6Al4V composites firstly increases and then decreases due to the synergy of grain size and different morphologies and distribution of TiB phases. The wear resistance of TiB/Ti6Al4V composites is far superior to that of Ti6Al4V alloy owing to the increased microhardness resulted from the uniform distribution of the hard TiB phase in the matrix.     

Sand Abrasive Wear Behavior of Hot Forged Al 6061-TiO2 Composites

Nickel-coated TiO₂ particulate reinforced Al6061 matrix composites developed using the vortex technique were hot forged at a temperature of 500 °C. A constant deformation ratio of 6:1 was adopted. Hot forged Al6061 alloy and Al6061-TiO₂ composites were then subjected to heat treatment by solutionizing at a temperature of 530 °C for duration of 2 h followed by ice quenching. Both natural and artificial aging at 175 °C were performed on the quenched samples from 2 to 8 h duration in steps of 2. Microstructure, microhardness, and dry sand abrasive wear behavior of both matrix alloy and developed composites in both as-forged and heat-treated conditions have been evaluated. Worn surface studies have been carried out using scanning electron microscope. Results have revealed that nickel-coated TiO₂ particles are uniformly distributed through out the matrix alloy. Microhardness of Al6061-TiO₂ composites increases with increase in percentage of reinforcement. Heat-treated forged alloy and its composites possesses higher hardness when compared with the forged composites. Forged Al6061-TiO₂ composites exhibited lower abrasive wear loss when compared with the forged matrix alloy. Heat treatment has a profound effect on the abrasive wear resistance of both as-forged Al6061 alloy and Al6061-TiO₂ composites.     

基于Ti中间层的B4C复合陶瓷扩散连接接头界面微观组织与力学性能

碳化硼(B₄C)复合陶瓷以其高硬度、高熔点、良好的耐磨性以及吸收中子能力的特性,广泛应用于制造防弹装甲材料,原子反应堆控制以及耐磨耐高温结构材料等领域.文中采用中间层Ti箔对碳化硼复合陶瓷(B₄C-SiC-TiB₂)进行扩散连接,研究了连接温度对连接界面组织及接头力学性能的影响.结果表明,在连接温度1300 ~ 1450 ℃下成功扩散连接了B₄C-SiC-TiB₂复合陶瓷,Ti与B₄C反应生成TiB₂和TiC.随着连接温度的升高,反应层变厚,而过厚的反应层会对接头的性能造成不利影响.在连接温度1300 ℃时,反应层的平均厚度约为5 μm,此时获得较高的接头抗剪强度100 MPa;在连接温度1450 ℃时连接层基本为TiB₂和TiC陶瓷相,此时扩散连接接头可以获得较高硬度(25.4 GPa).     

STRUCTURE AND PROPERTIES OF RE-Ni-B-Al_2O_3 COATING MATERIAL

1.IntroductionItiswellknownthatdiamond,carbide,boride,nitrideandoxidehavehighhardness,lowfrictioncoefficientandgoodwearresistance,yettheiruseislimitedbecauseoftheirlowtensilestrength,weakcapacity0fp0undingandp0ormachinability['].Whileins0lublesolidparticlesareaddedintheelectr0lessbathtoenablethemtoc0dep0sitwithmetals0naplatetoformauniformc0mp0sitelayer,theplatewouldpossessbettercharacteristicsthanthebaremetals0ralloysI2-6].Thestabilizerandactiveagentf0rthebatharedeveloppedbyalot0fexperimentson…     

Effects of Forming Conditions and TiC–TiB_2 Contents on the Microstructures of Self-Propagating High-Temperature Synthesized NiAl–TiC–TiB_2 Composites

The NiAl–TiC–TiB2 composites were processed by self-propagating high-temperature synthesis(SHS) method using raw powders of Ni, Al, Ti, B4 C, TiC, and TiB2, and their microstructure and micro-hardness were investigated. The TiC–TiB2 in NiAl matrix, with contents from 10 to 30 wt%, emerged with the use of two methods: in situ formed and externally added. The results show that all final products are composed of three phases of NiAl, TiC, and TiB2. The microstructures of NiAl–TiC–TiB2 composites with in situ-formed TiC and TiB2 are fine, and all the three phases are distributed uniformly. The grains of NiAl matrix in the composites have been greatly refined, and the micro-hardness of NiAl increases from 381 HV100 to 779 HV100. However, the microstructures of NiAl–TiC–TiB2 composites with externally added TiC and TiB2 are coarse and inhomogeneous, with severe agglomeration of TiC and TiB2 particles. The samples containing externally added 30 wt% TiC–TiB2attain the micro-hardness of 485 HV100. The microstructure evolution and fracture mode of the two kinds of NiAl–TiC–TiB2 composites are different.