原位反应合成TiN／Al2O3复合材料

以Al和TiO2为初始原料，经高能球磨及热压烧结工艺，原位合成了TiN／Al2O3复合材料。利用DTA，XRD及SEM等方法结合热力学计算，研究了该粉体的高能球磨过程和球磨粉体在后续热处理中的物相形成及转化规律。同时研究了以高能球磨及热压烧结工艺所制备的复合材料的力学性能和显微结构。结果表明：在球磨过程中粉料吸附并溶解了N2气，在后续热处理中原位反应形成了Ti2AlN相，当温度升高到一定程度时分解形成TiN，这有助于材料的致密化并使其力学性能提高。球磨粉体在1300℃、30MPa、保温、保压60min热压烧结条件下，可得到性能优异的TiN/Al2O3复合材料，该材料的抗弯强度为850MPa，断裂韧性为5．7MPa·m^1/2。     

SiO2与液态Al反应生成Al2O3/Al复合材料的研究

采用SiO2粉与液态Al反应制备Al2O3／Al复合材料，讨论了SiO2的加入量、反应温度、反应时间对反应速度的影响，分析了不同反应温度和保温时间下生成复合材料的微观结构。试验证明：当SiO2含量较低时，SiO2与Al发生完全反应，形成均匀Al2O3／Al复合层；当ω(SiO2)达一定量时，反应速度反而降低；保温时间为6～8h，反应速度最快，之后变慢。     

原位反应法制备A12O3/Al基复合材料的研究

利用原位反应制备了(Al2O3)p／Al复合材料，生成A1203颗粒分散度大．无聚集或偏聚现象，分布均匀。通过对反应所得材料的显微组织分析，(Al203)p与基体结台良好．界面无其他新相产生。试验证明：利用原位反应制备(Al203)p／Al复合材料．抗拉强度提高了25．6％，而伸长率仅下降了9％，在试验中加入Al2(SO4)3熔剂不仅细化Al2O3陶瓷颗粒，而且还起到辅助精炼和分散陶瓷相作用。     

原位生成Al2O3、TiB2和Al3Ti/Al复合材料的热循环行为

本文研究了Al-TiO2-B系原位生成Al2O3、TiB2和Al3Ti/Al颗粒增强铝基复合材料的热循环行为，研究结果表明了纯铝及B／TiO2摩尔比分别为0、1和2的颗粒增强铝基复合材料的热循环行为具有以下结果，纯铝和复合材料热循环后均产生了残余应变和滞后环；Al-TiO2-B系列复合材料热循环应变的各项指标均比纯铝基体大大降低，且具有较小的内耗功和较好的热稳定性，可以预测其具有较高的热疲劳寿命，热循环曲线能很好的评估复合材料在温度循环变化的环境中工作时的热稳定性和热疲劳。     

固液原位反应生成Al2O3（P）／Al复合材料的研究

采用CuO颗粒与Al熔体原位反应的方法制取了Al2O3(P)/Al复合材料,并对其显微组织、硬度及耐磨性进行分析和研究。试验结果表明：反应生成的Al2O3颗粒非常细小（2－5μm)弥散且均匀地分布于Al基体中,具有显著的增强效果,所得复合材料的硬度和耐磨性显著高于Al基体。     

原位Al2O3颗粒增强铜基复合材料的制备及微观组织

采用原位反应的方法成功制备了Al2O3颗粒增强铜基复合材料.对原位反应过程进行了热力学分析和动力学分析.SEM观察和EDS分析显示,原位反应生成的Al2O3颗粒分布于Cu基体中,且颗粒平均直径约为0.5μm,在材料中平整圆滑的Al2O3颗粒与基体结合良好.     

内氧化法制备Al2O3/Cu复合材料的再结晶

利用内氧化法制备了Al2O3/Cu复合材料,研究了该材料在不同冷拔变形量和Al2O3含量下,其硬度值随退火温度变化的规律,并进行了显微组织结构分析。结果表明:采用内氧化法制备的Al2O3/Cu复合材料,在铜基体中弥散分布着纳米级的Al2O3颗粒;经900℃×1h退火后,其硬度可保持室温的87%以上;其再结晶温度高达1000℃;变形量和Al2O3含量增加均使硬度提高,但对软化和再结晶温度影响不大。     

铝液与SiO2反应原位形成Al／Al2O3（P）复合材料的研究

将铸造方法与原位技术相结合研制出原位形成的Ａｌ／Ａｌ２Ｏ３（Ｐ）复合材料。向铝液中添加（搅入法）预先在３００℃下烘烤３ｈ、粒径为３００μｍ的ＳｉＯ２颗粒，发生如下反应：３ＳｉＯ２＋４Ａｌ＝３Ｓｉ＋２Ａｌ２Ｏ３，其结果，原位形成颗粒分布均匀的Ａｌ／Ａｌ２Ｏ３（Ｐ）复合材料     

原位生成Al2O3增强Al-4Mg基复合材料中的Al2O3/Al位向关系

综合搅拌铸造法和原位反应制备了Al2O3颗粒增强Al-4Mg基复合材料，并对制备的Al-4Mg基复合材料进行了透射电镜(TEM)观察分析，发现Al2O3／Al之间不存在固定的位向关系，但存在如下优先的位向关系：(1210)Al2O3∥(111)Al，[1012]Al2O3∥[112]Al，[2021]Al2O3∥[101]Al．     

固液原位反应生成Al_2O_3(P)/Al复合材料的研究

采用 Cu O颗粒与 Al熔体原位反应的方法制取了 Al2 O3( P) / Al复合材料 ,并对其显微组织、硬度及耐磨性进行分析和研究。试验结果表明 :反应生成的 Al2 O3颗粒非常细小 ( 2～ 5 μm)弥散且均匀地分布于 Al基体中 ,具有显著的增强效果。所得复合材料的硬度和耐磨性显著高于 Al基体     

Al-Si/Al_2O_3 in situ composite prepared by displacement reaction of CuO/Al system

Al2O3 particle-reinforced ZL109 composite was prepared by in situ reaction between CuO and Al.The microstructure was observed by means of OM,SEM and TEM.The Al2O3 particles in sub-micron sizes distribute uniformly in the matrix,and the Cu displaced from the in situ reaction forms net-like alloy phases with other alloy elements.The hardness and the tensile strength of the composites at room temperature have a slight increase as compared to that of the matrix.However,the tensile strength at 350 ℃ has reached 90.23 MPa,or 16.92 MPa higher than that of the matrix.The mechanism of the reaction in the CuO/Al system was studied by using of differential scanning calorimetry(DSC) and thermodynamic calculation.The reaction between CuO and Al involves two steps.First,CuO reacts with Al to form Cu2O and Al2O3 at the melting temperature of the matrix alloy,and second,Cu2O reacts with Al to form Cu and Al2O3 at a higher temperature.At ZL109 casting temperature of 750-780 ℃,the second step can also take place because of the effect of exothermic reaction of the first step.     

可加工性BN/Al2O3陶瓷基复合材料的制备

利用气相化学反应, 以H3BO3和CO(NH2)2作为BN源, 将纳米BN包覆到Al2O3颗粒表面, 经热压烧结制备出高强韧可加工BN/Al2O3复合材料. 材料的三点弯曲强度随BN含量的增加而缓慢降低, BN体积分数为30% 时, 仍达到446MPa; 断裂韧性随BN含量的增加而得到显著改善, 较单相氧化铝陶瓷提高近一倍. BN体积分数大于20%时, 该复合材料可用WC钻头在普通台式钻床上钻孔, 在小的轴向压力(10N)下, 钻孔速率大于1mm/min, 钻孔边缘平整, 没有崩裂现象, 内壁光滑, 粗糙度RZ =(6±0.5)μm. SEM观察显示, 加工未带来明显的损伤. 材料优异的力学性能及可加工性源自于基质中均匀分布的细小h-BN的颗粒增韧机制及其易解理的层状结构特点.     

In-situ synthesized (Al_3Zr+Al_2O_3)_p /A356 composites by direct melt reaction in Al-Zr-O system

1　INTRODUCTIONRecently ,muchattentionhasbeen paidtothedevelopmentofeffectivefabricationprocessesforpar ticulatereinforcedmetalmatrixcomposites (PRMM Cs) [13] .However,metalmatricesreinforcedwithparticlesformedinsituareanemerginggroupofdis continuouslyreinforcedcompositesthathavedistinctadvantagesovertheconventionalcomposites[4 ,5] .Inthein situfabricationprocess ,thespontaneousreac tionbetweenthereactantsisutilizedtosynthesizethereinforcementsinthemetalmatrix .Especially ,thedirectmelt…     

铝熔体中添加NH4Al(SO4)2制备Al/Al2O3复合材料

向铝熔体中添加脱水的硫酸铝铵,于900℃下发生分解反应,反应分解的Al2O3原位生成颗粒增强铝基复合材料。SEM观察表明,Al2O3颗粒在铝基体中细小弥散分布,形成球形的、不团聚的增强体颗粒。与基材相比,Al/Al2O3复合材料的耐磨损性能明显提高,耐磨性是基材的4倍,且由硫酸铝铵原位生成的复合材料耐磨性优于添加氧化铝形成的复合材料。拉伸实验结果显示,复合材料的抗拉强度没有明显变化,且塑性有所降低。     

Al2O3p/Al复合材料中颗粒粒径与形态对组织和性能的影响

选用 5 .0和 0 .15 μm两种粒径的Al2 O3 颗粒 ,制备了Al2 O3 体积分数为 40 %的铝基复合材料。利用透射电镜对两种复合材料拉伸前后的组织进行观察 ,结果表明 :5 μm尖角形Al2 O3 颗粒增强复合材料的铸态组织中存在高密度的位错 ,这主要是由于热错配应力引起的 ;0 .15 μm椭球形Al2 O3 颗粒增强复合材料的铸态组织中几乎观察不到位错 ,这与颗粒细小且为等轴状、分布弥散、界面附近应力分布均匀等因素有关。对拉伸断口附近显微组织的观察表明 ,前者基体中位错进一步增殖 ,后者则存在明显的位错环。室温拉伸结果表明亚微米Al2 O3p/Al复合材料中的这种微观组织有利于材料强度和塑性的提高     

Interfacial microstructure of 20% SO2/Al matrix composites reinforced with in situ formation ceramic phases

Al matrix composites reinforced with in situ ceramic phases by adding 20% SiO2 were fabricated by powder metallurgy process.The interfacial microstructure of the composites was studied by means of SEM and HREM.It was shown that the ceramic phases mainly composed of spinel MgAl2O4 are formed in situ in the original SiO2 particle and the size of small MgAl2O4 crystallites is about dozens of nanometers,which can adjacent to Al and Si.MgO could not found in original SiO2 particle but a little in matrix and may exist with Si,Mg2Si and Al.Si is mostly distributed in matrix and forms some segregation zones.The size of Mg2Si is about 50-100nm and can usually be seen in the matrix.     

Preparation of Al-Al3Ti in situ composites by direct reaction method

Al-Al3Ti composites were prepared by a direct reaction method, in which Al3Ti was formed by the reaction of Ti and Al in aluminum alloy melt. The morphology of Al3Ti changes apparently from the fine particle, needle-like to large block with the increase of Al3Ti content. The addition of magnesium can markedly change the morphology of Al3Ti and reduce their size. Short rod-like Al3Ti was formed and homogeneous distribution was obtained with the addition of 3 wt.% Mg. The effect of Al3Ti and Mg on the microstructure of Al-Al3Ti composites and the mechanism were also discussed.     

Microstructure and mechanical properties of 7075 Al alloy based composites with Al2O3 nanoparticles

A new method was used to fabricate 7075 Al alloy based composites with Al₂O₃ nanoparticles to improve the distribution of particles. In this study, nano-sized particles were fed into the molten alloy through the flow of argon gas, then the Al₂O₃/7075 composites were prepared by solid-liquid mixed casting. The results indicated that the composite samples showed fine microstructure and achieved a homogeneous distribution of particles. Also, it was found that relative to the as-cast 7075 alloy, the Al₂O₃/7075 composites exhibited higher mechanical properties, which is due to the effect of uniform distributed Al₂O₃ nanoparticles reinforcement.     

超声化学原位合成（Al3Zr＋ZrB2）／A356复合材料的力学行为

利用超声化学熔体原位反应技术合成颗粒增强(Al3Zr ZrB2)/A356复合材料,通过SEM原位拉伸实验及其断裂表面研究分析复合材料的断裂行为。结果表明,复合材料的抗拉强度、屈服强度和伸长率分别达到403.61MPa、343.98MPa和8.9%,较未施加超声作用的复合材料分别提高16.09%、12.9%和32.83%;复合材料的室温拉伸断口SEM形貌表现出明显的韧窝断裂特征,为塑性断裂。裂纹的萌生机制主要有基体在滑移过程中的位错作用机制、内生Al3Zr和ZrB2颗粒脱落或破碎形成的空穴成核机制和基体缺陷诱发机制;由于内生增强颗粒微观分布上的不均匀性,当主裂纹扩展前方遇到颗粒密集区时,其扩展方向偏向颗粒贫化区,绕过颗粒密集区,并沿颗粒富集区与贫化区的界面向前扩展、延伸,形成宏观裂纹。