共查询到19条相似文献,搜索用时 189 毫秒
1.
采用Ni-Ti复合箔片作为中间层,在990 ℃、低连接压力(0.1 MPa)下,通过瞬时液相(TLP)扩散连接制备了Ti3Al/Ti2AlNb异种合金接头。分析了保温时间(10~90 min)对Ti3Al/Ti2AlNb接头微观结构及力学性能的影响,并研究了TLP扩散连接接头的界面演变和形成机制。结果表明,Ti3Al/Ti2AlNb接头具有典型的“Ti3Al | Al0.5Nb0.5Ti3 | 残余 Ni | NiTi | NiTi2 | 残余 Ti | Al0.5Nb0.5Ti3 | Ti2AlNb”多层梯度结构。随着保温时间的延长,接头的抗剪切强度先增大后减小,当保温时间达到60 min时,Ti3Al/Ti2AlNb接头的抗剪切强度最大,达到167±12 MPa。另外,接头的断裂主要发生在Ti2AlNb/Ti附近的NiTi2层,并向Ti层延伸,呈现出脆性断裂的特征。 相似文献
2.
《稀有金属材料与工程》2017,(Z1)
通过2TiC-Ti-1.2Al体系的原位热压反应制备Ti_3AlC_2陶瓷,然后以59.2Ti-30.8Al-10Ti_3AlC_2(质量分数,下同,%)为反应体系,采用放电等离子烧结技术制备Ti_2AlC/Ti Al基复合材料。借助XRD、SEM分析产物的相组成和微观结构,并测量其室温力学性能。结果表明:原位热压烧结产物由Ti_3AlC_2和TiC相组成,Ti_3AlC_2呈典型的层状结构,TiC颗粒分布在其间;SPS法制备的Ti_2AlC/Ti Al基复合材料主要由Ti Al、Ti_3Al和Ti_2AlC相组成,Ti_2AlC增强相主要分布于基体晶界处,发挥了晶界/晶内内生型强化相的增强作用。力学性能测试表明:Ti_2AlC/Ti Al基复合材料的密度、维氏硬度、断裂韧性和抗弯强度分别为3.85 g/cm~3、5.37 GPa、7.17 MPa·m~(1/2)和494.85 MPa,穿晶、沿晶及层状撕裂等混合断裂特征对改善性能发挥了重要作用。 相似文献
3.
以Ti,Al和TiC为原材料,用无压煅烧合成法制备三元化合物Ti3AlC2。详细讨论了煅烧温度和铝含量对多晶Ti3AlC2纯度的影响。利用X射线衍射仪、场发射扫描电镜和场发射透射电镜研究了粉末材料的组织结构、晶粒大小、层板厚度和选区电子衍射花样。结果表明1300℃是合成Ti3AlC2粉末的最佳煅烧温度,1:1.2:2是Ti/Al/TiC原材料的最佳摩尔比。用热压法制备了不同烧结温度下的Ti3AlC2块体试样,在1300℃热压制备的Ti3AlC2块体的相对密度可达99.9%,其维氏硬度和三点抗弯强度分别为5.7 GPa和630 MPa。通过场发射扫面电镜观察材料的断口形貌,进一步分析了Ti3AlC2块体材料的强化机理。 相似文献
4.
以Ti3AlC2和Ni合金粉为原料,采用原位热压烧结法制备了TiCx/Ni合金复合材料。高温下Ni合金引起Ti3AlC2分解形成TiCx,Al原子和少部分Ti原子从基体中脱离,并与Ni合金发生反应。添加20Vol%Ti3AlC2和40Vol%Ti3AlC2时,TiCx中x的值分别为0.625和0.715。利用XRD、SEM和 EDS等表征方法对复合材料进行物相分析以及微观结构分析。研究表明,原位生成的TiCx与Ni合金基体结合牢固,所制备的复合材料具有优异的力学性能,添加20%Ti3AlC2和40%Ti3AlC2时,复合材料的压缩强度分别达到了2.2 GPa和2.09 GPa,相应的压缩断裂应变分别为9.6%和8.5%。 相似文献
5.
采用微束弧热态焊技术熔化沉积Ti2AlNb合金丝材,在TiAl基合金环状试样上制备出Ti2AlNb基合金梯度材料。利用金相显微镜(OM)、扫描电子显微镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)方法及显微硬度测试,对沉积态TiAl/Ti2AlNb梯度材料的显微组织、相组成和显微硬度进行了分析。结果表明:微束弧热态焊技术熔化沉积的Ti2AlNb基合金组织由β相、O相和α2相组成,并且随着距离母材距离的增加,梯度材料呈现出γ+α2/γ→β(固溶体)+O→β2+O+α2(魏氏组织)→β(固溶体)+O的相变趋势。梯度材料的硬度呈现出波浪式的分布。另外结合各元素对组织稳定性的影响,以及微束等离子技术所具有的特殊热循环和热积累效应,对梯度材料在微束等离子沉积过程中的相变规律进行了解释。 相似文献
6.
利用综合热分析仪、背散射扫描电镜(BSE)和能谱分析(EDS)对Al2O3/Ti2AlN复合材料在900 ℃,1 000 ℃和1 100 ℃/20 h空气中连续氧化20h后的氧化增重及氧化层截面进行了研究。结果表明:Al2O3/Ti2AlN复合材料在空气中的氧化行为符合抛物线规律,在900 ℃,1 000 ℃和1 100 ℃/20 h氧化增重分别为2.78×10-2 kg/m2、10.4 ×10-2 kg/m2、21.9 ×10-2 kg/m2,抛物线速率常数相应为1.08×10-8 kg2/m4s、1.44×10-7 kg2/m4s、6.56×10-7 kg2/m4s,氧化激活能为274 kJ/mol。氧化层主要由TiO2和Al2O3组成的,连续的Al2O3次外层可以提高其抗氧化性能。氧化层结构的改变是由于氧化温度对Ti4+、Al3+由基体表面向外扩散和O2-向内扩散的影响,以及TiO2和Al2O3在不同温度下的形核生长速率导致的。对Al2O3/Ti2AlN而言,控制材料与氧化气氛的界面是提高该材料抗氧化性能的关键。 相似文献
7.
利用纳米Sn粉高的表面活性,通过微米Mg粉与纳米Sn粉的机械合金化高效合成了含原位纳米Mg2Sn相的复合粉末,将所得复合粉末热压烧结,获得高性能纳米Mg2Sn增强镁基复合材料。对比研究了不同机械合金化时间对镁基复合材料组织、性能的影响,结果表明:随着机械合金化时间的延长,由纳米Mg2Sn相组成的团簇尺寸不断减小,分布更加均匀,烧结态Mg2Sn/Mg复合材料的各项力学性能也得到不断提高。 相似文献
8.
采用粉末层叠和整体热压烧结的方法,制备了Y2Ti2O7/316L不锈钢功能梯度复合材料。经金相显微镜、X射线衍射仪和电子探针分析确定,该材料在金属和氧化物界面处实现了成分和微观组织的梯度过渡。对不同梯度含量复合材料的力学性能测试表明,界面处的力学性能存在相应的梯度变化,即随各层金属相含量的逐渐增加,过渡区材料的致密度、抗弯强度不断提升,而硬度则不断下降。 相似文献
9.
王维艾桃桃冯小明李文虎蒋鹏袁新强孛海娃景然 《材料热处理学报》2017,(3):10-15
以Ti-Al-Ti_3AlC_2为反应体系,采用真空热压技术(1100℃×1 h)制备Ti_2AlC/TiAl基复合材料。借助XRD、SEM等测试手段分析相组成以及微观结构,并测量其密度、维氏硬度、抗弯强度、抗压强度和断裂韧性等室温力学性能。结果表明,产物主要由TiAl、Ti_2AlC和Ti_3Al相组成。利用Ti_3AlC_2分解反应原位自生的Ti_2AlC增强相主要分布于基体晶界处,部分钉扎于晶内,且随着Ti_2AlC生成量的增大,团聚现象加剧。室温力学性能测试表明,Ti_2AlC/TiAl基复合材料的力学性能明显优于单相TiAl材料,当Ti_3AlC_2掺杂量为10 mass%时,综合性能较好,密度、硬度、抗弯强度、抗压强度和断裂韧性分别为3.97 g/cm^3、4.82 GPa、488.61 MPa、1340 MPa和5.68 MPa·m^(1/2)。断裂机制主要表现为沿晶断裂、穿晶断裂、裂纹偏转与桥联;颗粒相增韧、裂纹偏转与桥联以及层状增韧是主要的增韧方式。 相似文献
10.
11.
Baoyan Liang Mingzhi Wang Jinfeng Sun Qin Zou Xin Han 《International Journal of Refractory Metals and Hard Materials》2009,27(5):927-930
The mechanically activated sintering process was adapted to synthesize Ti3AlC2 using 3Ti/Al/2C/0.05Sn powder mixtures. The result showed that the powders containing TiC, Ti3AlC2 and Ti2AlC were obtained by mechanical alloying (MA) 3Ti/Al/2C powders. Addition of appropriate Sn reduced the content of Ti2AlC and enhanced the synthesis of Ti3AlC2 significantly. The powders with highest content of Ti3AlC2 were obtained by MA 3Ti/Al/2C/0.05Sn powders. Through pressureless sintering the mechanical alloyed powders at 900–1100 °C for 2 h, the high purity Ti3AlC2 material with fine organization was produced. 相似文献
12.
Porous preforms were fabricated by cold-pressing process using powder mixture of TiC, TiO2 and dextrin. After pyrolysis and sintering, Al melt was infiltrated into the porous preforms, leading to the formation of Ti3AlC2-Al2O3-TiAl3 composite. Effects of cold-pressing pressure of preforms on microstructures and mechanical properties of the composites were studied. Synthesis mechanism and toughening mechanism of composite were also analyzed. The results shows that TiO2 is reduced into Ti2O3 by carbon, the decomposition product of dextrin, which causes the spontaneous infiltration of Al melt into TiC/Ti2O3 preform. Then, Ti3AlC2-Al2O3-TiAl3 composite is in-situ formed from the simultaneous reaction of Al melt with TiC and Ti2O3. With the increase of cold-pressing pressure from 10 MPa to 40 MPa, the pore size distribution of the preforms becomes increasingly uniform after pre-sintering, which results in the reduction of defects, and the decrease of property discrepancy of composites. Nano-laminated Ti3AlC2 grains and Al2O3 particles make the fracture toughness of TiAl3 increase remarkably by various toughening mechanisms including stress-induced microcrack, crack deflection and crack bridging. 相似文献
13.
Preparation of the ternary carbide Ti2AlC was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) from the elemental powder compacts of Ti:Al:C = 2:1:1, TiC-containing samples with TiC of 6.67–14.3 mol%, and Al4C3-containing samples with Al4C3 of 1.96–10 mol%. Effects of TiC and Al4C3 addition were studied on combustion characteristics and the degree of phase conversion. Due to the growth of laminated Ti2AlC grains, the reactant compact was subjected to an axial elongation during the SHS process. Because the addition of TiC and Al4C3 led to a decrease in the reaction temperature, the flame-front propagation velocity was correspondingly reduced for the TiC- and Al4C3-containing samples when compared with the elemental reactants. Based upon the XRD analysis, formation of Ti2AlC along with a secondary phase TiC was identified in the synthesized products. The grains of Ti2AlC are typically plate-like with a size of 10–20 μm and several laminated Ti2AlC grains form a layered structure. The content of Ti2AlC yielded from the elemental powder compacts is about 85 wt%. The addition of TiC was found to facilitate the formation mechanism and therefore to enhance the extent of Ti2AlC conversion approaching 90 wt%. As a result of the reduced exothermicity of the reaction, however, the content of Ti2AlC decreased slightly in the products synthesized from the Al4C3-added samples. 相似文献
14.
Ti2AlC is strengthened by substituting Ti with V to form (Ti,V)2AlC solid solutions. The Vickers hardness, flexural strength, shear strength and compressive strength are enhanced by 29%, 36% and 45% for (Ti0.8,V0.2)2AlC solid solution, respectively. The strengthening mechanism is discussed. 相似文献
15.
《Intermetallics》2017
In order to improve the mechanical properties of TiAl alloys, TiAl composites with different solidification paths were synthesized by metallurgical method. Results show the TiC disappears and Ti2AlC increases when the Al content is more than 42% (at.%, similarly hereinafter). Small TiC particles are located in Ti2AlC grains with irregular shapes when the Al content is 40%, and they translate into clubbed Ti2AlC with increasing of Al. This metallurgy method can solve the defects of the Al lacking and the residual TiC. The γ phase increases between lamellar colonies with the increasing of Al. When the Al content is 48%, the fully lamellar structure transforms into a duplex microstructure and there are small Ti2AlC phases in γ phases, because the forming of Ti2AlC phase must consume Al. The compressive strength increases up to 1678.68 MPa as Al content is 46 at.%, and then decrease to 1460.22 MPa, the compressive strain increases and then keeps stabilization with the increasing Al. The maximum strength improves 38.82% and the maximum strain improves 121.37%. The Ti2AlC/TiAl composites fracture behaviors are load transferring behavior, crack deflection, trans-lamellar cracking and extraction of carbide reinforcements. The Ti2AlC phase and the fully lamellar structure improve the mechanical properties. 相似文献
16.
In this paper we report on the electrochemical corrosion of select MAX phases, namely Ti2AlC, (Ti,Nb)2AlC, V2AlC, V2GeC, Cr2AlC, Ti2AlN, Ti4AlN3, Ti3SiC2 and Ti3GeC2 in 1 M NaOH, 1 M HCl and 1 M H2SO4 solutions. Polarization characteristics recorded in 1 M NaOH show that V2AlC, V2GeC and Cr2AlC undergo active dissolution at potentials more positive than the corrosion potential, while Ti2AlC, (Ti,Nb)2AlC, Ti3SiC2 and Ti3GeC2 passivate. In the 1 M HCl solutions, Ti2AlC, V2AlC and V2GeC actively dissolve; Ti3SiC2 and Ti3GeC2 passivate. Depending on potential, (Ti,Nb)2AlC and Cr2AlC showed trans-passive behavior. In 1 M H2SO4 solutions, Ti2AlC, (Ti,Nb)2AlC, Ti3SiC2 and Ti3GeC2 passivate, V2AlC and V2GeC show active dissolution, while Cr2AlC exhibits trans-passive behavior. Ti2AlN and Ti4AlN3 were passive in all solutions except in 1 M HCl, where Ti2AlN showed trans-passive behavior. Given that the corrosion behavior of (Ti,Nb)2AlC is unlike either Ti or Nb, the behavior of the former cannot be predicted from that of the latter. 相似文献
17.
Yunchao Mu Jifeng GuoBaoyan Liang Qinsheng Wang 《International Journal of Refractory Metals and Hard Materials》2011,29(3):397-400
A mixture of Ti/Si/TiC/diamond powders was employed to fabricate the Ti3SiC2 bonded diamond composite using the spark plasma sintering-reactive synthesis method. The addition of diamond does not inhibit the synthesis of Ti3SiC2 in the sintered product. In the matrix Ti3SiC2 grains developed lamellar morphology with an average length size of 5-10 μm. Ti3SiC2 matrix displays good pullout strength with diamond, and the Ti3SiC2 bonded diamond material exhibits good wear resistance. 相似文献
18.
Marie Sonestedt Jenny Frodelius Mats Sundberg Lars Hultman Krystyna Stiller 《Corrosion Science》2010,52(12):3955-3961
The oxidation behaviour of Ti2AlC bulk and high velocity oxy-fuel spray deposited coatings has been investigated for temperatures up to 1200 °C. X-ray diffraction and electron microscopy show that bulk Ti2AlC forms a continuous layer of α-Al2O3 below a layer of TiO2 at temperatures as low as 700 °C. Oxidation of the Ti2AlC coatings is more complex, and also involves the phases Ti3AlC2, TiC, and TixAly, formed during the spraying process. α-Al2O3 is observed, however, it is unevenly distributed deep into the material, and does not form a continuous layer essential for good oxidation resistance. 相似文献
19.
X.H Wang 《Corrosion Science》2003,45(5):891-907
The isothermal oxidation behavior of bulk Ti3AlC2 has been investigated at 1000-1400 °C in air for exposure times up to 20 h by means of TGA, XRD, SEM and EDS. It has been demonstrated that Ti3AlC2 has excellent oxidation resistance. The oxidation of Ti3AlC2 generally followed a parabolic rate law with parabolic rate constants, kp that increased from 4.1×10−11 to 1.7×10−8 kg2 m−4 s−1 as the temperature increased from 1000 to 1400 °C. The scales formed at temperatures below 1300 °C were dense, adherent, resistant to cyclic oxidation and layered. The inner layer of these scales formed at temperatures below 1300 °C was continuous α-Al2O3. The outer layer changed from rutile TiO2 at temperatures below 1200 °C to a mixture of Al2TiO5 and TiO2 at 1300 °C. In the samples oxidized at 1400 °C, the scale consisted of a mixture of Al2TiO5 and, predominantly, α-Al2O3, while the adhesion of the scales to the substrates was less than that at the lower temperatures. Effect of carbon monoxide at scale/substrate was involved in the formation of the continuous Al2O3 layers. 相似文献