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901.
Mechanical Properties and Interlaminar Fracture Toughness of Glass‐Fiber‐Reinforced Epoxy Composites Embedded with Shape Memory Alloy Wires 下载免费PDF全文
Li‐Dan Xu Ming‐Fang Shi Xiao‐Yu Sun Zhen‐Qing Wang Bin Yang 《Advanced Engineering Materials》2018,20(3)
902.
Tensile Strength Evolution and Damage Mechanisms of Al–Si Piston Alloy at Different Temperatures 下载免费PDF全文
Meng Wang Jianchao Pang Yu Qiu Haiquan Liu Shouxin Li Zhefeng Zhang 《Advanced Engineering Materials》2018,20(2)
903.
Effects of Cu on Microstructures,Mechanical, and Magnetic Properties of Fe–Ni–P Alloys Fabricated by Liquid Phase Sintering 下载免费PDF全文
The Fe–Ni–P–Cu alloys with different copper content (0, 0.5, 1, and 2 wt%) are fabricated by liquid phase sintering (LPS) at 950 °C. The nano‐Cu powder is mechanically mixed for 90 min with Fe–Ni–P composite powder using the ethanol as the medium. The microstructure, microhardness and compressive properties of Fe–Ni–P–Cu alloys are investigated. The results indicate that the copper is beneficial to improve the mechanical properties of sintered specimens. The sample contains a small amount of γ‐(Fe, Ni) phase when the copper content is 1 wt%, which results in its the highest compressive yield strength (948.1 MPa). The highest microhardness of 371 HV is accessible in Fe–Ni–P–Cu alloy with 2 wt% Cu. The fracture surface analysis indicates that sintered specimens with Cu addition exhibit a typical intergranular mode. 相似文献
904.
Modulated Triple‐Material Nano‐Heterostructures: Where Gold Influenced the Chemical Activity of Silver in Nanocrystals 下载免费PDF全文
Puspanjali Sahu Gyanaranjan Prusty Amit K. Guria Narayan Pradhan 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(33)
For efficient charge separations, multimaterial hetero‐nanostructures are being extensively studied as photocatalysts. While materials with one heterojunction are widely established, the chemistry of formation of multijunction heterostructures is not explored. This needs a more sophisticated approach and modulations. To achieve these, a generic multistep seed mediated growth following controlled ion diffusion and ion exchange is reported which successfully leads to triple‐material hetero‐nanostructures with bimetallic‐binary alloy‐binary/ternary semiconductors arrangements. Ag2S nanocrystals are used as primary seeds for obtaining AuAg‐AuAgS bimetallic‐binary alloyed metal–semiconductor heterostructures via partial reduction of Ag(I) using Au(III) ions. These are again explored as secondary seeds for obtaining a series of triple‐materials heterostructures, AuAg‐AuAgS‐CdS (or ZnS or AgInS2), with introduction of different divalent and trivalent ions. Chemistry of each step of the gold ion–induced changes in the rate of diffusion and/or ion exchanges are investigated and the formation mechanism for these nearly monodisperse triple material heterostructures are proposed. Reactions without gold are also performed, and the change in the reaction chemistry and growth mechanism in presence of Au is also discussed. 相似文献
905.
In this study, the crack propagation behaviors in the equiaxed and equiaxed-columnar grain regions of a heat-treated laser additive manufacturing (LAM) TC11 alloy with a special bi-modal microstructure are investigated. The results indicate that the alloy presents a special bi-modal microstructure that comprises a fork-like primary α (αp) phase surrounded by a secondary α colony (αs) in the β phase matrix after the heat treatment is completed. The samples demonstrate a fast crack growth rate with larger da/dN values through the equiaxed grain sample versus across the equiaxed-columnar grain sample at low ΔK values (<13.8). The differences that are observed between the crack propagation behaviors (in the crack initiation stage) of the samples can be mostly attributed to the different size and morphology of the αp lamellae and αs colony within the grains in the equiaxed and columnar grain regions rather than the grain boundaries. The cracks prefer to grow along the α/β boundary with a smooth propagation route and a fast propagation rate in the equiaxed grain region, where the αp and α clusters have a large size. However, in the columnar grain region, small and randomly distributed αp lamellae generate a zigzag-shaped propagation path with a reduction in the da/dN value. Additionally, the change in the size of the αp lamellae in the equiaxed grains (heat affected bands, HAB) is also observed to influence the propagation behavior of the crack during the crack initiation stage. 相似文献
906.
The corrosion behavior of 2A02 Al alloy under simulated marine atmospheric environment has been studied using mass-gain, scanning electron microscope/energy dispersive spectroscopy (SEM/EDS), laser scanning confocal microscopy, X-ray diffraction spectroscopy and localized electrochemical methods. The results demonstrate that the relationship between the corrosion induced mass-gain and the corrosion time is in accordance with the power rule. The mass-gain increases gradually during the corrosion time, while the corrosion rate decreases. With ongoing of the corrosion, corrosion products film changed from a porous to a compact structure. The various spectroscopic data show that the corrosion products films composed mainly of Al(OH)3, Al2O3 and AlCl3. The electrochemical corrosion behavior of the 2A02 Al alloy was studied by electrochemical impedance spectroscopy (EIS). 相似文献
907.
《材料科学技术学报》2019,35(7):1261-1269
High depth-to-width ratio friction stir welding is an attractive method for the joining demands of aluminum profiles, which is sparked with its extremely low heat input and high mechanical performance. In this study, the joint formation mechanism was studied by a numerical model of plastic flow combined with experimental approaches. A fluid-solid-interaction algorithm was proposed to establish the coupling model, and the material to be welded was treated as non-Newtonian fluid. The thread structure and the milling facets on tool pin promoted drastic turbulence of material. The thread structure converged the plasticized material by its inclined plane, and then drove the attached material to refill the welds. The milling facets brought about the periodic dynamic material flow. The thread structure and the milling facets increased the strain rate greatly under the extremely low heat input, which avoided the welding defects. The condition of the peak temperature of 648 K and the strain rate of 151 s−1 attributed to the lowest coarsening degree of precipitate. The tensile strength of the joint reached 265 MPa, equivalent to 86% of base material. The amelioration via the material flow model inhibits the welding defects and optimizes the parameter intervals, providing references to extracting process-structure-property linkages for friction stir welding. 相似文献
908.
《材料科学技术学报》2019,35(10):2336-2344
Ti-Cu alloys with different Cu contents (3, 5 and 7 wt%) were fabricated and studied as novel antibacterial biomaterials for dental application. The Ti-Cu alloys were annealing treated at different temperatures (740 °C, 830 °C and 910 °C) in order to obtain three typical microstructures, α-Ti + Ti2Cu, α-Ti + transformed β-Ti, and transformed β-Ti. Mechanical, antibacterial and biocorrosion properties of Ti-Cu alloys with different microstructures were well analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), tensile test, electrochemical test and antibacterial test. The results indicated that the Ti-Cu alloys with microstructure of α-Ti + Ti2Cu showed the best ductility compared with other Ti-Cu alloys with microstructures of α-Ti + transformed β-Ti and complete transformed β-Ti, and meanwhile, increase of the Cu content significantly contributed to the decreased ductility due to the increasing amount of Ti2Cu, which brought both solid solution strengthening and precipitation strengthening. Finally, the Ti-5Cu alloy with microstructure of α-Ti + Ti2Cu exhibited excellent ductility, antibacterial property and corrosion resistance, providing a great potential in clinical application for dental implants. 相似文献
909.
《材料科学技术学报》2019,35(11):2705-2713
In this study, the Zn-0.5 wt%Zr (Zn-Zr) alloy was treated by laser surface remelting (LSR), and then the microstructure and degradation mechanism of the remelting layer were investigated and compared with the original as-cast alloy. The results reveal that after LSR, the bulky Zn22Zr phase in the original Zn-Zr alloy is dissolved and the coarse equiaxed grains transform into fine dendrites with a secondary dendrite arm space of about 100 nm. During the degradation process in simulated body fluid (SBF), the corrosion products usually concentrate at some certain areas in the original alloy, while the corrosion products distribute uniformly and loosely in the LSR-treated surface. After removing the corrosion products, it was found that the former suffers obvious pitting corrosion and then localized corrosion. The proposed mechanism is that corrosion initiates at grain boundaries and develops into the depth at some locations, and then leads to localized corrosion. For the LSR-treated sample, corrosion initiates at some active sites and propagates in all directions, corrosion takes place in the whole surface with distinctly uniform thickness reduction, while the localized corrosion and peeling of bulky Zn22Zr particles were eliminated. The electrochemical results also suggest the uniform corrosion of LSR-treated sample and localized corrosion of original sample. Based on the results, a new approach to regulate the corrosion mode of the biodegradable Zn alloy is proposed. 相似文献
910.
创建一个包含多变体结构特征的双态组织几何模型,提出一种变形协调性的评估方法,采用以率相关滑移为主的晶体塑性有限元本构关系,研究了具有不同组织特征的Ti-6Al-4V合金双态组织的高温拉伸行为。结果表明:在多晶变形过程中,αp相承载了更多的应变;在变形后的样品中,出现了大致对称分布于拉伸方向两侧的高应变交叉条带;存在于αp与βT之间的包围结构特征,可加剧局域应变分配的差异;随着αp相体积分数的升高应变量降低,整体应变协调性先较快降低而后平稳;随着αs片层厚度的增加高应变条带特征弱化,整体应变协调系数升高;含双变体αs片层团簇结构的βT组织,其应变协调性低于含单变体和三变体的组织。 相似文献