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1.
Metallic thin films have attracted much attention owing to their unique mechanical properties,which are widely used in micro-/nano-devices.In this review,several key topics about the thin films in the micron to nano-scales are covered.First,the plastic deformation mechanisms in face-centered-cubic(FCC)metals,in particular the sizedependent deformation twinning at small scales,are discussed based on a deformation-mechanism map.Microstructural evolution is then briefly discussed from the perspective of the ratio of effective-to-internal stresses,while the stress-driven grain growth is discussed based on a twinning-mediated mechanism.The last section elucidates the size-dependent mechanical properties of metallic thin films,such as yield strength,ductility and mechanical fatigue behavior. 相似文献
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Bin Yao Wei Hong Tianwu Chen Zhubing Han Xinwei Xu Renchao Hu Jianyu Hao Changhao Li He Li Steven E. Perini Michael T. Lanagan Sulin Zhang Qing Wang Hong Wang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(14):1907499
Polymer composites with electrically conductive fillers have been developed as mechanically flexible, easily processable electromagnetic interference (EMI) shielding materials. Although there are a few elastomeric composites with nanostructured silvers and carbon nanotubes showing moderate stretchability, their EMI shielding effectiveness (SE) deteriorates consistently with stretching. Here, a highly stretchable polymer composite embedded with a three-dimensional (3D) liquid-metal (LM) network exhibiting substantial increases of EMI SE when stretched is reported, which matches the EMI SE of metallic plates over an exceptionally broad frequency range of 2.65–40 GHz. The electrical conductivities achieved in the 3D LM composite are among the state-of-the-art in stretchable conductors under large mechanical deformations. With skin-like elastic compliance and toughness, the material provides a route to meet the demands for emerging soft and human-friendly electronics. 相似文献
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采用熔体快淬法制备了化学组成为Al80-xSi20Mnx(x=0、5%、7%、10%(摩尔分数))的锂离子电池合金负极材料。分析了合金的相组成、热力学状态、微观组织和与锂离子电池相关的电化学性能。结果显示,当Mn含量位于5%~7%时,熔体快淬Al80-xSi20Mnx合金可得到单一的过饱和固溶体和部分非晶,前10次电化学循环中具有比Al70-xSi30Mnx(x=0、5%、7%、10%(摩尔分数))多相合金高的容量,与含40%Si、相同Mn含量的合金相近。分析表明,在含20%~40%Si、5%~10%Mn的熔体快淬Al基合金中,锂主要储存在过饱和固溶体中,晶界和相界对储锂有重要贡献。合金的循环性能与Al基过饱和固溶体的成分有关,第三组元Mn的加入提高固溶体的过饱和度,并通过影响Li原子的扩散,改善循环性能。 相似文献
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液态硅浸渍反应和混合酸(HNO3+HF)刻蚀制备多孔SiC陶瓷 总被引:1,自引:0,他引:1
通过液态硅浸渍反应和混合酸(HNO3+HF)腐蚀制备了多孔SiC陶瓷。扫描电镜(SEM)结果显示,多孔SiC具有不规则且相互连通的孔道结构,其微观形貌特征源于滤纸和酚醛树脂制备的多孔碳。多孔SiC的气孔率可达62%,混合酸腐蚀的多孔SiC的弯曲强度和断裂韧性均小于致密SiC/Si复合体。并提出用循环氧化-腐蚀机制解释游离态Si的腐蚀过程。 相似文献
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The effect of fluoride corrosion on the bonding strength of Ti-porcelain under different static loads was investigated. The adhesion between the titanium and porcelain was evaluated by three-point flexure test. After being immersed in artificial saliva with pH 2.7 under 0 N, 1 N and 2 N static loads, respectively, no decrease of the bonding strength of Ti-porcelain occurred. However, the decrease of bonding strength was about 30%, 37%, and 46% after being immersed in artificial saliva with pH 2.7/F− 100 ppm under 0 N, 1 N and 2 N static loads, respectively. The failure of the titanium-porcelain predominantly occurred at the titanium-oxide interface. Immersion in the artificial saliva did not affect the fracture mode of the titanium-porcelain system. The corrosion of the Ti-porcelain interface resulted in the reduction of bonding strength. The static loads enhanced the F− corrosion on the Ti-porcelain interface. 相似文献
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The microsuucture and room-temperature tensile properties of Til4,a new α+Ti2Cu alloy,were investigated after conventional forging at 950℃ and semi-solid forging at 1000 and 1050℃,respectively.Results show that coarse grains and grain boundaries are obtained in the semi-solid alloys.The coarse grain boundaries are attributed to Ti2Cu phase precipitations occurred on the grain boundaries during the solidification.It is found that more Ti2Cu phase precipitates on the grain boundaries at a higher semi-solid forging temperature,which forms precipitated zones and coarsens the grain boundaries.Tensile tests exhibit high strength and low ductility for the semi-solid forged alloys,especially after forging at 1000℃.Fracture analysis reveals the evidence of ductile failure mechanisms for the conventional forged alloy and cleavage fiacture mechanisms for the alloy after semi-solid forging at 1050℃. 相似文献
10.
研究了Ti-5Al-4Zr-10Mo-3Cr合金经过β相区固溶(880 ℃)、不同温度时效(540~620 ℃)处理后次生α相(αs)析出形貌及其对力学性能的影响。结果表明:随着时效温度由540 ℃升高至620 ℃,合金中析出αs相片层厚度由0.030 μm增加到0.142 μm,屈服强度由1353 MPa降低至1074 MPa,断后伸长率由2.5%升高至11.4%,即时效析出的微米级片层αs能够显著调控合金的力学性能。此外,时效温度升高使合金的拉伸断裂由沿晶脆性断裂为主转变为韧窝穿晶为主的韧性断裂方式。Ti-5Al-4Zr-10Mo-3Cr合金时效析出的片层状αs相的厚度大于0.1 μm,合金的断后伸长率≥6%。当时效温度为600 ℃时,合金的硬度为387 HV10,抗拉强度为1182 MPa,伸长率为8.5%,具有良好的强塑性匹配。 相似文献