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1.
为了提高高温构件的热疲劳性能、减少表面裂纹,研究激光冲击对ZCuAl10Fe3Mn2合金硬度、表面形貌、残余应力和热疲劳性能的影响。采用扫描电子显微镜(SEM)和能谱仪(EDS)分析合金的显微组织和裂纹形貌。结果表明:在4 J脉冲能量下,激光冲击能显著改善合金的热疲劳性能。在热应力和交变应力的作用下,试样缺口附近组织氧化而变得疏松多孔,促使萌生多条微裂纹。其中,竖直方向的微裂纹变为主裂纹,主要以裂尖前沿空洞连体的形式扩展;其他方向的微裂纹沿晶界生长而发生组织脱落现象。 相似文献
2.
Qianyu Yang Chen Gao Xuemei Zhang Chihui Tsou Xingyu Zhao Manuel Reyes De Guzman Zejun Pu Xinyue Li Yue Lu Chunyan Zeng Li Yuan Yiqing Xia Yuping Sheng Yiqing Fu 《大分子材料与工程》2021,306(7):2100093
Hydrogels with excellent stiffness, toughness, anti-fatigue, and self-recovery properties are regarded as promising water-containing materials. In this work, a dual physically cross-linked (DPC) sodium alginate (SA)/poly[acrylamide (AAm)-acrylic acid (AAc)-octadecyl methacrylate (OMA)]-Fe3+ hydrogel is reported, which is constructed by hydrophobic association (HA) and ionic coordination (IC). The optimal DPC hydrogel demonstrates excellent mechanical performance: tensile modulus of 0.65 MPa, tensile strength of 3.31 MPa, elongation at break of 1547%, and toughness of 27.8 MJ m–3. SA/P(AAm-AAc-OMA)-Fe3+ DPC hydrogels also exhibit prominent anti-fatigue and self-recovery performance (99.1–109.7% modulus recovery and 90.4–108.9% dissipated energy recovery after resting for 5 min without additional stimuli at ambient temperature) through the reconstruction of reversible physical cross-linking. Some of the SA/P(AAm-AAc-OMA)-Fe3+ DPC hydrogels even exhibit a stretching-induced strengthening effect, which is similar to the performance of muscle—“the more training, the more strength.” Hence, the combination of HA and IC will provide an effective approach to design DPC hydrogels with desirable mechanical performances and a longer service life for wider applications of soft materials. 相似文献
3.
为了研究盐腐蚀环境下内嵌FRP筋加固混凝土界面的黏结性能,对27个内嵌FRP筋加固混凝土试件进行盐腐蚀后的单端拉拔试验,分析试件的受力过程和破坏模式,研究内嵌FRP筋黏结长度、腐蚀时间和FRP筋类型对界面黏结性能的影响。结果表明:盐腐蚀的试件破坏模式分为结构胶劈裂、FRP筋拉断和结构胶劈裂且FRP筋弯折等3种,且以结构胶劈裂破坏为主。盐腐蚀环境下内嵌FRP筋混凝土试件的黏结应力与黏结长度、破坏模式与腐蚀时间有关。盐腐蚀环境会影响混凝土、黏结材料及FRP筋的力学性能,加剧黏结界面失效破坏。腐蚀时间为30 d和90 d的内嵌BFRP筋加固混凝土试件的耐盐腐蚀能力高于内嵌GFRP筋加固混凝土试件的,腐蚀时间为60 d的内嵌GFRP筋加固混凝土试件的耐盐腐蚀能力优于内嵌BFRP筋试件的。根据试验数据拟合了盐腐蚀环境下内嵌FRP筋加固混凝土界面黏结-滑移本构关系,其拟合优度达到0.988 0。 相似文献
4.
Wei-Hao Chen Chia-Yueh Chou Bao-Jhen Li Shao-Liang Cheng Cheng-Yi Liu 《Journal of the American Ceramic Society》2021,104(12):6579-6588
Columnar wurtzite grains were formed in sputtered ZnO thin films deposited on a plastic polyethylene terephthalate substrate. Selected-area diffraction patterns reveal that the columnar grains in the sputtered films present two preferred growth planes, namely, the basal (0002) and prismatic (100) growth planes. The diffraction patterns obtained also confirm that the microstructure of sputtered indium tin oxide thin films is amorphous in nature. Tensile tests indicate that the fracture strain of the ZnO thin film occurs between 1.73% and 2.14%, while the fracture strain of the indium tin oxide thin film occurs between 0.24% and 0.67%. Thus, the fracture toughness of the sputtered ZnO thin film is greater than that of the sputtered indium tin oxide thin film. High-resolution transmission electron microscopic images demonstrate that edge and screw dislocations could be identified in the sputtered ZnO thin films. Moreover, edge and screw dislocation movements may, respectively, be observed in the basal- and prismatic-oriented ZnO columnar grains of the sputtered ZnO thin films. Our results indicate that movements of the edge and screw dislocations in the basal- and prismatic-oriented ZnO columnar grains account for the plastic deformation of the investigated ZnO thin films under tensile stress. 相似文献
5.
Generally, the good combination of pre-deformation and aging can improve the mechanical strength of the Al–Cu–Li–Mg alloys. However, the effects of pre-deformation on competitive precipitation relationship and precipitation strengthening have not been clarified in detail in Al–Cu–Li–Mg alloys with high Mg. In the present study, the effects of pre-deformation level on the microstructure and mechanical properties of an Al–2.95 Cu–1.55 Li–0.57 Mg–0.18 Zr alloy have been investigated. It is found that the introduction of dislocation by 5% pre-deformation can facilitate the precipitation of new successive composite precipitates and T _1 precipitates along the sub-grain boundaries or dislocations and inhibit the precipitation of dispersive GPB zones which is the main precipitates of the alloys without pre-deformation. The introduction of 5% pre-deformation can enhance the mechanical properties considerably. When the pre-deformation level increases from 5 to 15%, the number density of the successive composite precipitates and T _1 precipitates increases, and the aspect ratio of T _1 precipitates decreases. The decrease in T _1 precipitate aspect ratio and the increment of the successive composite precipitates result in the reduction in precipitation strengthening. Therefore, the increase in pre-deformation level from 5 to 15% does not further improve the mechanical properties of the alloys, although the dislocation strengthening increases continuously. 相似文献
6.
由于型钢翼缘外露,部分包覆钢-混凝土组合(PEC)柱耐火极限很难满足设计需求。为探究PEC柱抗火性能加强方法,得到经济合理的加强措施,通过ABAQUS有限元分析软件建立了轴压作用下PEC柱的温度场及热力学性能有限元分析模型,并用已有试验数据验证模型可靠性,探讨了PEC柱在高温下的温度变化、受力机理和破坏模式。对不同加强措施下轴压PEC柱抗火性能进行了参数分析,研究了荷载比、纵筋配筋率、翼缘面积比、截面尺寸、长细比和防火涂料厚度等参数对PEC柱耐火极限的影响规律。结果表明:PEC柱耐火极限随荷载比、长细比、翼缘面积比的降低而明显提高,随着防火涂料厚度与截面尺寸的增加而明显提高; 在参数分析的基础上,回归得到考虑防火涂料厚度影响的PEC柱耐火极限简化计算公式,研究结果将为PEC构件抗火设计提供科学依据。 相似文献
7.
Chao Ye Qing Chang Penghui Lei Wenhui Dong Qing Peng 《Journal of the American Ceramic Society》2022,105(9):5921-5928
Ti3SiC2 samples were irradiated by a 6-MeV Si+ ion to a fluence of 2 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
8.
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
9.
通过向模拟A/O生化池中投加填料强化该工艺处理小城镇污水的处理效果。结果表明,当O段溶解氧的质量浓度控制在2~3 mg/L,温度控制在28℃,进水p H在7.2~7.8的条件下,该工艺的优化水力停留时间为8 h、污泥回流体积比为20%,模拟装置在该优化工况下运行时,对COD、NH4+-N及TP的平均去除率分别为91.1%、96.3%、73.3%。为提高除磷效果,增加后置化学辅助除磷后,TP平均去除率可达86%,出水中COD、NH(4)+-N含量均能达到GB 18918-2002的一级A标准,TP含量能达到一级B标准,去除效果较好。 相似文献
10.
辐照硬化是金属材料的辐照效应之一,开展辐照硬化机理研究有助于设计可靠的反应堆结构材料。辐照产生的缺陷会对位错运动造成阻碍,被认为是辐照硬化的主要原因。近年来快速发展的位错动力学模拟方法为材料的微观组织变化和宏观力学性能之间建立起了桥梁,被广泛用于辐照硬化机理研究。对于一些辐照缺陷如位错环和层错四面体,位错动力学软件已能模拟它们对位错网络演化以及宏观力学响应的影响,使辐照硬化的定量预测成为可能。本文从位错动力学模型、不同类型辐照缺陷硬化效应的位错动力学模拟以及辐照硬化理论模型发展三个方面,综述了辐照硬化位错动力学模拟的研究进展,并展望该研究领域的主要科学问题。 相似文献