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1.
将冷轧Ti/Al层状复合材料在675~750 ℃下进行不同时间的退火处理,退火过程中钛和铝都保持过剩,研究了Ti/Al层状复合材料的界面微观组织演变。结果表明:Ti和Al的界面层由2个亚层组成,其中一个为紧密的TiAl3亚层,其微观结构为紧密的TiAl3层,其中分布着随机取向的充满Al的裂纹,另一个为颗粒状的TiAl3亚层,其微观组织结构是颗粒状的TiAl3分布在Al基体中。在不同的退火温度和时间条件下,紧密TiAl3亚层的厚度几乎没有变化,但是颗粒状亚层的厚度随着退火温度及时间的增加而增加;另外,界面层中的TiAl3颗粒的体积分数在不同的温度下均随着退火时间的延长而下降。因此提出了反应扩散模型来描述界面层的形成机理,在此模型中,TiAl3相是化学反应和扩散的结果,并且也考虑了TiAl3相的溶解。计算结果表明TiAl3相的形成与生长由化学反应控制,其等效厚度与退火时间之间遵循线性规律,这主要是因为Ti和Al原子能够快速地通过紧密的薄TiAl3亚层。  相似文献   
2.
付中原 《轧钢》2021,38(5):105-108
针对普阳钢铁有限公司生产的6 mm厚钛微合金化S355JR薄规格钢板出现室温冲击不合的问题,对其化学成分、组织性能及生产工艺进行了分析。结果表明,连铸二冷强冷细化了TiN颗粒,使加热时更多的有效Ti溶解并于轧后析出,导致铁素体硬化是钢板常温冲击不合的原因。为此,在不便改变连铸工艺的前提下,调整了S355JR钢的化学成分,严格控制C、Ti含量,并将Mn质量分数由1.2%降至1.0%,有效地改善了6 mm厚S355JR钢板的常温冲击性能,提高了产品合格率。  相似文献   
3.
杨波  孙健  郭宏丽 《金属热处理》2021,46(4):118-121
采用控制轧制-控制冷却-淬火-回火工艺制备20 mm 厚的Ti微合金化中碳钢板,研究了控制冷却工艺(冷却速度)对该钢有效晶粒尺寸和析出相的影响,并探讨了其强韧化机理。结果表明:冷却速度越快,有效晶粒尺寸越小,马氏体板条宽度越窄,含Ti析出相越细小,使其兼具高强度和良好的塑性韧性。主要是由于快速冷却保留了轧制时获得的晶体缺陷和形变能,使再加热奥氏体细化,而且快速冷却抑制了Ti在冷却过程中析出,使Ti处于过饱和状态,再加热过程中逐渐析出细小的含Ti析出相,能更有效地阻止奥氏体晶粒长大。有效晶粒细化以及纳米级含Ti析出相使该钢板具有良好的力学性能。  相似文献   
4.
The joining of liquid-phase sintered SiC (LPS-SiC) ceramics was conducted using spark plasma sintering (SPS), through solid state diffusion bonding, with Ti-metal foil as a joining interlayer. Samples were joined at 1400 °C, under applied pressures of either 10 or 30 MPa, and with different atmospheres (argon, Ar, vs. vacuum). It was demonstrated that the shear strength of the joints increased with an increase in the applied joining pressure. The joining atmosphere also affected on both the microstructure and shear strength of the SiC joints. The composition and microstructure of the interlayer were examined to understand the mechanism. As a result, a SiC-SiC joining with a good mechanical performance could be achieved under an Ar environment, which in turn could provide a cost-effective approach and greatly widen the applications of SiC ceramic components with complex shape.  相似文献   
5.
Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2.  相似文献   
6.
Ti3SiC2 samples were irradiated by a 6-MeV Si+ ion to a fluence of 2 × $ \times $ 1016 Si+ ions/cm2 at 300°C followed by annealing at 900°C for 5 h. A transmission electron microscope was used to characterize microstructural evolution. The phase of Ti3SiC2 transformed from the hexagonal close-packed (HCP) to a face-centered cubic structure after irradiation. Hexagonal screw dislocation networks were identified at the deepest position of the irradiated area, which are the products of dislocations reactions. After annealing, the irradiated region has reverted to the original HCP structure. High-density cavities and stacking faults were formed along the basal planes. In addition, ripplocations have been observed in the irradiated region in the Ti3SiC2 sample after annealing. Our insights into the formation processes and corresponding mechanisms of these defect structures might be helpful in the material design of advanced irradiation tolerance materials.  相似文献   
7.
利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、电子背散射衍射(EBSD)及物理化学相分析法等技术研究了V含量对Ti-V复合微合金钢在不同卷取温度下组织和力学性能的影响。结果表明,两种Ti-V复合微合金钢在500~650℃卷取时,组织均由多边形铁素体和珠光体组成,增加V含量会抑制珠光体的形成;500~650℃区间卷取时,增加V含量使均匀延伸率和总延伸率有一定程度降低,而抗拉强度和屈服强度显著提高,卷取温度对均匀延伸率和总延伸率的影响不大,在600℃卷取时,两种实验钢的综合力学性能均达到最佳;V含量的增加使得在600℃卷取时尺寸小于10 nm的(Ti, V)C粒子数量显著增加,高钒钢的析出强化增量σp在183 MPa左右,其强化机制主要为沉淀强化和细晶强化,V含量是影响Ti-V复合微合金钢的沉淀强化增量和屈服强度的主要因素。  相似文献   
8.
The electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V were investigated through Tafel polarization, potentiostatic polarization and AC impedance measurements. The results show that the solution treatment−aging (STA) process aggravates the element micro-segregation compared to the annealing process, leading to varied Al and V contents of the phases from different samples. It is proven that either Al-rich or V-rich condition can highly affect the electrochemical dissolution behaviors due to thermodynamical instability caused by element segregation. The dissolution rate in the metastable passivation process is controlled by the stability of the produced film that is affected by phases distribution, especially the difficult-to-dissolve phase. And then, the dissolution rate of the phases in the transpassivation region is consistent with the rank in the activation process because the dense film is not capable of being produced. Compared to the annealed sample, the higher dissolution rate of the STA sample is beneficial to the electrochemical machining (ECM) of Ti6Al4V.  相似文献   
9.
In-situ bending and stretching were conducted on hot-rolled and annealed Ti/Al/Mg/Al/Ti laminates, with a focus on crack initiation and propagation of intermetallics and component layers, which helps to clarify their deformation behavior and fracture forms. The results show that delamination is the early fracture form of laminate with or without intermetallics at Al/Mg interface, so Al/Mg interfacial bonding strength determines the mechanical properties of laminate. Various and irregular intermetallics cracks lead to Al/Mg interface delamination in annealed laminate and help to release stress. Necking and fracture of component layers are observed at the late deformation stage, and the sequence is Al, Mg and Ti layers, resulting from their strength. Angle between crack propagation direction and stretching direction of Mg layer both in rolled and annealed laminates is around 45° due to the effect of shear deformation, and crack convergence leads to final complete fracture of Mg layer.  相似文献   
10.
The <110>-oriented BaTiO3 ceramics were fabricated using BaCO3 matrix and H1.08Ti1.73O4.nH2O (HTO) template particles, and the mechanism of BaTiO3 phase formation was investigated. The dielectric, ferroelectric, and piezoelectric properties were also investigated. The transformation of the HTO phase into the TiO2 bronze or TiO2 (B) phase was observed at 600°C, where the BaTiO3 nucleation was accompanied by the formation of a Ba2TiO4 phase. The TiO2 phase reacted with the Ba2TiO4 phase at 800°C to give a BaTiO3 phase, whereas its reaction with the BaTiO3 resulted in the formation of BaTi2O5 phase that got decomposed into BaTiO3 and Ba6Ti17O40 phase at sintering temperature ≥1300°C. Sintering with samples’ embedding in BaTiO3 powders prevented the formation of the Ba6Ti17O40 secondary phase. The crystallographic orientation along the <110> direction (F110) was developed by the epitaxial grain growth mechanism. In addition to the contribution of the grain-size increment for enhancing the F110, the preservation of the platelike structure was also found to have a significant impact. The ceramics prepared by the embedded sintering (grain size ≈12.4 µm and F110 = 83%) exhibited the room-temperature dielectric constant of 1708 and piezoelectric strain constant of 445 pm/V, which are higher than those of the BaTiO3 ceramics with randomly oriented grains.  相似文献   
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