Fabrication and properties of Al matrix composites strengthened by in situ alumina particulates

New aluminum matrix composites strengthened by Al2O3 particulates through stirring cast by adding NH4Al（SO4）2 to the molten aluminum have been fabricated. TEM observation shows that in-situ Al2O3 particulates are generally spherical and they are uniformly distributed in the Al matrix. Dry sliding wear test results show that the volume loss of the unreinforced Al matrix is about three times that of the Al2O3 reinforced metal matrix composite （MMC） and the volume loss of the MMC fabricated by adding Al2O3 is larger than that of the MMC by adding NH4Al（SO4）2. Lubricating sliding wear test results show that the volume loss of the MMCs increases more slowly than that of the matrix with the increasing of the load.     

Corrosion resistance of Molybdenum Nitride modified Ti6Al4V alloy in HCl solution

The Mo-N surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo-N modified Ti6Al4V alloy were investigated by X-ray diffraction （XRD） and glow discharge optical emission spectroscopy （GDOES）. The Mo-N modified layer contains Mo-N coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo-N modified Ti6Al4V alloy reveals that the outmost surface of the Mo-N modified Ti6Al4V alloy is composed of phase Mo2N （fcc） and Mo2N （tetr）. The electrochemical corrosion performance of the Mo-N modified Ti6Al4V alloy in 0.5 mol/L HCl solution was investigated and compared with that of Ti6Al4V alloy. The chemical corrosion performance of the Mo-N modified Ti6Al4V alloy in boiling 37% HCl solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that self-corroding electric potentials and corrosion-rate of the Mo-N modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 0.5 mol/L HCl solution. The corrosion-rate of the Mo-N modified Ti6Al4V alloy is lower than that of Ti6Al4V alloy in boiling 37% HCl solution.     

Interfacial reaction mechanism of TiBw/Ti6Al4V composites and Inconel 718 alloys by GTAW heat transmission

A good joint of Ti Bw/Ti6Al4V composites and Inconel 718 alloys was obtained by Gas Tungsten Arc Welding(GTAW) heat transmission. The interfacial reaction mechanism of joint was investigated and analyzed in details. Owing to the heat input applied on the surface of Ti Bw/Ti6Al4V composites, a solid-state reaction layer appeared at the interface of Ti Bw/Ti6Al4 V composites to Inconel 718 alloys. The thickness of the reaction layer was obviously increased with increasing heat input.Developing of reaction layer mainly depended on the diffusion of elements of Ti and Ni through the interface during welding to form solid solutions and intermetallic compounds(IMCs). The reaction layer can be divided into Ti-rich zone(layer 2) and Nirich zone(layer 1). In Ni-rich zone, relatively coarse dendrites were the predominant, however, more brittle IMCs like Ti2Ni were found in the Ti-rich zone. Micro hardness of reaction layer was much higher than that of base metal. While a slight decrease of hardness was found between Ti-rich zone and Ni-rich zone due to the formation of TiNi.     

Ti6Al4V合金表面纳米管阵列的制备

以氢氟酸和铬酸为电解液,采用阳极氧化法在Ti6Al4V合金表面制备高密度的纳米管阵列.利用场发射扫描电镜、X射线衍射仪和X射线光电子能谱对多孔氧化膜的形貌和结构进行分析,利用极化曲线和电化学阻抗谱研究了电解液中CrO3的作用机理.结果表明:电解液种类决定能否形成多孔氧化膜,而电解液的浓度影响多孔氧化膜的形貌和孔径大小;纳米管阵列氧化膜主要由大部分非晶态组织的TiO2,Al2O3和少部分晶态的Al2TiO5,Al3Ti5O2,Al2O3组成,氧化膜内的Al,Ti原子比高于基体中的Al,Ti原子比;CrO3浓度的高低会影响氧化膜的结构.     

再烧结Al2TiO5-ZrO2复合材料的性能研究

在钛酸铝粉体中分别引入2%,5%、8%的纳米ZrO2粉体,经1350℃,1400℃,1450℃,1500℃烧结获得Al2TiO5-ZrO2复相材料,对获得的Al2TiO5-ZrO2复合材料破碎再烧结进行性能研究,结果表明：再烧结Al2TiO5-ZrO2复相材料钛酸铝晶粒发育更加完全,经1500℃再烧结的试样抗热震性能明显提高.     

外加Al2O3颗粒对Ti-Al-TiO2系合成产物微观结构的影响

Ti-Al-TiO2体系外加不同含量的Al2O3颗粒获得了Al2O3／TiAl基复合材料,研究了产物的相组成及微观组织。结果表明：Al2O3颗粒多分布在基体晶界处。随外加Al2O3含量的增大,晶粒变小,但增强相颗粒团聚严重。外加Al2O3量存在一个临界值。含量过高,易造成结构疏松,不致密,形成大的气孔,且由于TiO2的活化作用,会造成外加的Al2O3颗粒烧结呈板状联结分布;含量较低,颗粒与界面的结合不够紧凑,但颗粒的结晶度较好。     

Microstructure and abrasive wear behaviour of anodizing composite films containing Si C nanoparticles on Ti6Al4V alloy

Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and X-ray photoelectron spectroscopy（XPS） were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film（3.73×10-8 A/cm2）. The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.     

The Influence of Mo Additive on the Microstructure and Property of Ti/Al_2O_3 Composite

1　IntroductionBecausethemetal ceramiccompositeisalwaysfabri catedatahightemperature ,theinterfacialreactionbe tweenmatrixandreinforcementisinevitableandformsabrittleinterfacialzone ,whichisdetrimentaltocompositeproperties .Thisisthemaincauseforhinderingtheprepa rationandapplicationoftitaniummatrixcomposites .Atpresent,variousapproachescanbeadoptedtoinhibitorreducethereinforcement matrixreaction .Theuseofhigh speedandlowerprocessingtemperatureduringcompositefabrication ,settingaprotectivecoati…     

A mesomechanical ductility model of SiCp/Al composite

1 INTRODUCTIONAl alloy matrix composites reinforced with SiCparticles are widely usedin aerospace , military andcivil industries because of their high specificstrength, modulus , wear resistance and fatigue re-sistance . With the increase of volume fraction ofSiC,the tensile ductility al ways decreases ,the e-lastic modulus increases ,and the strength changescomplexly .It is a noticeable issue to opti mize themechanical properties .Recently , many researchershave established some mechani…     

Preparation of TiAl/Al_2O_3 composites by combustion synthesis

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｔａｎｉｕｍａｌｕｍｉｎｉｄｅｓｂａｓｅｄｏｎＴｉＡｌｈａｖｅｅｘｃｅｌ ｌｅｎｔｐｏｔｅｎｔｉａｌｔｏｔａｋｅｔｈｅｐｌａｃｅｏｆｃｏｎｖｅｎｔｉｏｎａｌｔｉｔａｎｉ ｕｍａｎｄｎｉｃｋｅｌａｌｌｏｙｓｉｎａｄｖａｎｃｅｄｓｐａｃｅｃｒａｆｔｄｕｅｔｏｔｈｅｉｒｌｏｗｄｅｎｓｉｔｙ ,ｇｏｏｄｅｌｅｖａｔｅｄ ｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈａｎｄｈｉｇｈｒｅｓｉｓｔａｎｃｅｔｏｏｘｉｄａｔｉｏｎ[1～ 3] .Ｈｏｗｅｖｅｒ ,ｔｈｅｗａｙｔｏｐｒａｃｔｉｃａｌａｐｐ…     

Preparation of TiAl/Ti2AlC Composites with Ti/Al/C Powders by In-situ Hot Pressing

TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2AlC compasites.In the holding stage, ternary Ti2AlC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.     

Microstructures and Mechanism of Al_2O_3/Al Composites Fabricated by the Reaction between SiO_2 and Molten Aluminum

1　IntroductionAmongtheavailablemethodsforfabricatingcompos ite ,thein situreactionsynthesispossessestechnicalandeconomicadvantages :simpleprocess ,lowfabricationcost .Throughthechemicalreactionbetweenliquidandsolid ,in situreinforcedceramicparticleswithfinedimen sionandgooddistributioncanbeformed .Theparticleshaveawellcombinedinterfacewiththematrixandhavenopollutionofimpurities .Thecompositeobtainedbyin situreactionhasexcellentproperties ,soithaswideap plications .Inthefabricationofthein sit…     

Al2O3对3Ti/Si/2C体系自蔓延高温合成Ti3SiC2的影响

以3Ti/Si/2C粉体为原料,通过自蔓延高温合成技术合成了Ti3SiC2材料。研究了Al2O3助剂对自蔓延高温合成Ti3SiC2的影响。研究结果表明,3Ti/Si/2C粉体会发生自蔓延反应,产物的组成相为TiC、Ti3SiC2和Ti5Si3,产物中Ti3SiC2含量约为23%。添加适量的细粒度Al2O3可显著促进反应合成Ti3SiC2,3Ti/Si/2C/0.1Al2O3原料反应后得到的产物中Ti3SiC2含量达64%。     

Reactive Processing and Mechanical Properties of Al/SiCP Composite

0　ＩｎｔｒｏｄｕｃｔｉｏｎＡｌ/ＳｉＣＰｃｏｍｐｏｓｉｔｅｓｈａｖｅｈｉｇｈｓｐｅｃｉｆｉｃｓｔｒｅｎｇｔｈａｎｄｍｏｄｕｌｕｓ,ｈｉｇｈｗｅａｒｒｅｓｉｓｔａｎｃｅａｎｄｇｏｏｄｗｏｒｋａｂｉｌｉｔｙ .Ｔｈｅｙｓｈｏｗｇｏｏｄｐｒｏｓｐｅｃｔｆｏｒｉｎｄｕｓｔｒｙａｐｐｌｉｃａｔｉｏｎ .Ｔｈｅｃｏｓｔ ｅｆ ｆｅｃｔｉｖｅｐｒｏｃｅｓｓｉｎｇｔｅｃｈｎｏｌｏｇｉｅｓｏｆＡｌ/ＳｉＣＰｃｏｍｐｏｓｉｔｅｓｃｏｎ ｔｉｎｕｅｔｏｂｅａｋｅｙｒｅｓｅａｒｃｈａｒｅａ .Ｓｔｉｒｃａｓｔｉｎｇｉｓｔｈｅｍｏ…     

基于单颗磨粒划切试验的SiCp/Al复合材料表面去除机理研究

碳化硅颗粒增强铝基（SiCp/Al）复合材料中含有不规则碳化硅颗粒使得材料内部形成大量非理想截面,为材料表面的有效去除带来困难. 为了揭示材料去除机理,进行SiCp/Al 复合材料单颗磨粒变切深划切的表面去除仿真分析和试验验证. 研究结果表明,界面破坏对表面创成有重要影响,存在铝合金基体撕裂、界面分离,碳化硅颗粒裸露、裂纹扩展、破碎脱落、压入铝合金基体、碎片滑擦材料表面等去除过程,碳化硅颗粒中部大面积破碎脱落形成凹坑,并在刀具推挤作用下对材料进行二次切削,使铝合金基体表面形成非连续裂纹. SiCp/Al复合材料中由于铝合金基体的存在,实际划切深度小于名义切削深度. 研究可以为SiCp/Al复合材料去除机理与加工研究提供一定借鉴.     

热处理对2524铝合金显微组织及力学性能影响

在400℃下对铸态2524铝合金进行轧制成形,总变形量为90%,采用光学金相显微镜、拉伸试验机等设备检测轧制板材显微组织及力学性能.研究结果表明：随着固溶温度的升高,Al2Cu,Al2CuMg等第二相粒子数量逐渐减少,在490℃～500℃下基本固溶进铝基体中,其显微硬度值随着固溶温度的升高逐渐增大,当固溶温度为490℃时其显微硬度值为131.4 HV;2524铝合金轧制板材经490℃/20 min＋190℃/22 h处理后,其抗拉强度为485 MPa,延伸率为13.5%.     

掺杂对Al_2O_3/TiAl复合材料性能的影响

本研究采用Ti-Al-TiO2-La2O3体系,通过热压烧结工艺原位合成了Al2O3/TiAl复合材料.借助X射线衍射(XRD)、扫描电镜(SEM)等分析研究了材料的物相组成和微观组织结构,同时分别将掺杂La2O3和掺杂Fe2O3对合成Al2O3/TiAl复合材料微观结构和力学性能的影响进行了对比.结果表明:掺杂La2O3合成的Al2O3/TiAl复合材料基体尺寸相对掺杂Fe2O3合成产物较小,分散更加均匀,致密度更高.当La2O3掺杂量为3.93wt%时,Al2O3/TiAl复合材料的抗弯强度和断裂韧性达到最大值,分别为701.95MPa和7.79MPa·m1/2.由于稀土氧化物具有对基体和增强颗粒的净化,细化晶粒等作用,因此提高了TiAl基体与Al2O3增强颗粒结合强度,所以掺杂La2O3合成材料的力学性能相比掺杂Fe2O3合成的产物较高.     

不同Al含量的Ti/Al合金靶对磁控溅射离子镀TiAlN薄膜力学性能的影响

采用不同Al含量的Ti/Al合金靶材在硬质合金刀具上沉积TiAlN薄膜,研究靶材中不同的Al含量对TiAlN薄膜表面粗糙度、硬度以及膜基结合力等性能的影响,通过显微硬度仪、划痕仪、金相显微镜和XRD等仪器分别对薄膜的硬度、结合力、组织结构等主要性能进行测试分析。实验结果表明:随着Ti/Al合金靶中Al含量的增加,TiAlN薄膜的硬度先增加后减小,膜基结合力逐渐增加;当Al在Ti/Al合金靶材中所占的比值为2:3时,TiAlN薄膜的硬度、耐磨性等综合力学性能最佳。     

On the Character and Mechanism of the Drilling Force For SiCw/Al Composite

ＯｎｔｈｅＣｈａｒａｃｔｅｒａｎｄＭｅｃｈａｎｉｓｍｏｆｔｈｅＤｒｉｌｌｉｎｇＦｏｒｃｅＦｏｒＳｉＣｗ／ＡｌＣｏｍｐｏｓｉｔｅ￥ＨＡＮＲｏｎｇｄｉ；ＬＩＸｉａｎｇｑｉ；ＹＡＮＣｈｕｎｈｕａ；ＧＥＮＧＬｉｎ（韩荣第，李向麒，严春华，耿林）（Ｄｅｐｔ．ｏ...     

Al(OH)_3对SEBS/PP/OMMT插层复合体系性能的影响

通过熔融共混法制备了氢化苯乙烯-丁二烯-苯乙烯(SEBS)/聚丙乙烯(PP)/Al(OH)3/有机蒙脱土(OMMT)复合材料,并采用锥形量热仪、拉伸测试仪等测试了材料的阻燃性能和力学性能。测试结果表明,添加Al(OH)3,使SEBS/PP/OMMT复合材料的热释放速率、峰值热释放速率和总热释放显著降低,且随着Al(OH)3添加量的增加,复合材料的峰值热释放速率降低愈明显;体系中OMMT和Al(OH)3添加量(质量分数)均在10%时复合材料的综合性能最佳。