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المؤلفون: Liang, Chen, Wang, HaiPeng

المصدر: Advanced Engineering Materials; Aug2021, Vol. 23 Issue 8, p1-13, 13p

مصطلحات موضوعية: SOLIDIFICATION, ALLOYS, MICROSTRUCTURE, GRAIN refinement

مستخلص: The strength and ductility trade‐off dilemma has limited the wide application of TiAl‐based alloys. Here, a new insight into the potential for increasing the strength and ductility of a hypoperitectic Ti–48 at% Al–8 at% Nb alloy is accomplished by the electromagnetic levitation (EML) technique. Moreover, a systematic analysis of the primary and subsequent peritectic solidification kinetics is conducted in the undercooling range of 308 K. Assisted by a high‐speed camera, in situ observation of the liquid–solid (primary β‐Ti phase and peritectic α‐Ti phase) interface migration is accomplished. When the alloy melt is undercooled to 240 K, high‐ordered nanotwins are observed in the Ti–48 at% Al–8 at% Nb alloy, which form a unique hierarchical microstructure. Upon further increasing the undercooling, the density of these nanotwins is significantly enhanced. The room‐temperature compression results reveal that the strength and ductility increase up to 140% and 150%, respectively. This is mainly ascribed to the remarkable grain refinement, formation of nanotwins with various orientations, accumulation of dislocations and stacking faults, and retention of the metastable γ‐phase. The superior combination of strength and ductility indicates the possibility to fabricate high‐ordered nanotwins via rapid solidification, thus improving the performance of γ‐TiAl‐based alloys. [ABSTRACT FROM AUTHOR]

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المؤلفون: Liu, Wei, Chang, Jian, Wang, Haipeng

المصدر: Steel Research International; Jul2018, Vol. 89 Issue 7, p1-1, 9p, 1 Chart, 9 Graphs

مصطلحات موضوعية: MICROSTRUCTURE, METALLIC composites, ALLOYS, MICROALLOYING, X-ray diffraction

مستخلص: Rapid solidification of highly undercooled Fe–Co–Ni alloys is realized by drop tube technique. The microstructures of Fe–10%Co–10%Ni, Fe–15.6%Co–12%Ni, and Fe–10%Co–20%Ni alloys are all composed of single α(Fe) solid solution phase, which are confirmed by the results of XRD and DSC. With the decrease of droplet diameters, the cooling rate and undercooling increase, meanwhile, the microstructural characteristic of α(Fe) phase transforms from coarse dendrites to equiaxed grains. The size of coarse dendrites decreases to one tenth for the refined equiaxed grains. Employing the Vickers hardness and nano indenter techniques, the mechanical properties of α(Fe) dendrites are investigated. The average Vickers microhardness of α(Fe) phase is remarkably enhanced with the decrease of the grain size. Due to the more homogenous solute distribution in the dendrite trunks, the nanohardness presents a gentle fluctuation. Once the droplet diameter exceeds a critical value, the solutes concentrate at the grain boundaries. As a result, the closer the indenters to the grain boundary, the larger the nanohardness. [ABSTRACT FROM AUTHOR]

: Copyright of Steel Research International is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Zhai, Bin, Zhang, PengChao, Liang, Chen, Chang, Jian, Wang, HaiPeng

المصدر: Advanced Engineering Materials; Nov2022, Vol. 24 Issue 11, p1-1, 1p

مصطلحات موضوعية: LEVITATION, MICROSTRUCTURE, COPPER-titanium alloys, ALLOYS

مستخلص: V addition makes the Ti-45%Al alloy transform from -TiAl alloy to SB 2 sb -Ti SB 3 sb Al alloy and changes the mechanical properties of and SB 2 sb phases. Connecting Solidified Microstructure with Compression Properties for Bulk Ti-Al Alloys with V Addition Conducted by Electromagnetic Levitation and First Principle Bulk Ti-Al-based alloys with a mass of 30 g are prepared by electromagnetic levitation (EML). [Extracted from the article]

: Copyright of Advanced Engineering Materials is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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المؤلفون: Wang, Haipeng, Yan, Peng, Guan, Yingchun

المصدر: Materials (1996-1944); Dec2021, Vol. 14 Issue 23, p7469, 1p

مصطلحات موضوعية: FIBROUS composites, ALLOYS, CARBON composites, METALLIC composites, FRACTURE strength, TITANIUM alloys, HETEROJUNCTIONS

مستخلص: The development of heterojunctions with a strong bonding interface between metals and non-metals has attracted much attention owing to their great potential for use in lightweight structures. Laser joining technology, which emerged as a fast and reliable method, has proven its feasibility and unique advantages in joining metal to polymer matrix composites. Herein, an optimized laser joining configuration has been employed to realize high-quality joining of titanium alloy and carbon fiber-reinforced composite. Cross-sectional microstructures of laser-produced joints reveal that micro-bubbles near the interface have been effectively suppressed and eliminated due to the continual clamping pressure applied to the joined area during the joining process. Tensile tests suggest that the joint strength increases with structure density on a titanium alloy surface, and the greatest fracture strength of joints reaches more than 60 MPa even after experiencing a high–low temperature alternating aging test. For higher structure density (>95%), the joints fail by the fracture of parent plastics near the joined area due to the tensile-loading-induced peel stress at the edges of the overlap region. Otherwise, the joints fail by interfacial shear fracture with breakage when the structure density is lower than 91.5%. The obtained high-performance heterojunctions show great potential in the aerospace and automotive fields. [ABSTRACT FROM AUTHOR]

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المؤلفون: Wang Haipeng, Wei Bingbo

المصدر: Chinese Science Bulletin; May2005, Vol. 50 Issue 10, p945-949, 5p, 7 Diagrams

مصطلحات موضوعية: SURFACE tension, LIQUIDS, EUTECTIC alloys, ELECTROMAGNETISM, CALORIMETRY, TEMPERATURE measurements, ALLOYS

مستخلص: The surface tension and specific heat of stable and metastable liquid Ni70.2Si29.8 eutectic alloy were measured by electromagnetic levitation oscillating drop method and drop calorimetry. The surface tension depends on temperature linearly within the experimental undercooling regime of 0–182 K (0.12 TE). Its value is 1.693 N·m^-1 at the eutectic temperature of 1488 K, and the temperature coefficient is -4.23 ⊗ 10^-4 N·m^-1·K^-1. For the specific heat measurement, the maximum undercooling is up to 253 K (0.17 TE). The specific heat is determined as a polynomial function of temperature in the experimental temperature regime. On the basis of the measured data of surface tension and specific heat, the temperature-dependent density, excess volume and sound speed of liquid Ni70.2Si29.8 alloy are predicted theoretically. [ABSTRACT FROM AUTHOR]

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المؤلفون: Wang Haipeng, Cao Chongde, Wei Bingbo

المصدر: Chinese Science Bulletin; Feb2004, Vol. 49 Issue 3, p220-224, 15p, 6 Graphs

مصطلحات موضوعية: SOLIDIFICATION, ALLOYS, CRYSTALLIZATION, HEAT, COOLING

مستخلص: Droplets of Ni-31.4%Pb monotectic alloy with different sizes are rapidly solidified during free fall in a drop tube. The theoretical calculations indicate that the undercooling was achieved before solidification exponentially depends on droplet diameter. The maximum undercooling of 241 K (0.15Tm) is obtained in the experiments. With the increase of undercooling, the volume fraction of monotectic cells increases, and the L2(Pb) grains are refined. Calculations of the nucleation rates of L2(Pb) and α-Ni phases indicate that L2(Pb) phase acts as the leading nucleation phase during the monotectic transformation. [ABSTRACT FROM AUTHOR]

: Copyright of Chinese Science Bulletin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)