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343 results on '"Wen, HaiMing"'

18. Structural changes of Ti3SiC2 induced by helium irradiation with different doses

Author

Zhang, Hongliang, Su, Ranran, Shi, Liqun, OConnor, Daryl J, and Wen, Haiming

Subjects
Condensed Matter - Materials Science
Abstract

In this study, the microstructure changes of Ti3SiC2 MAX phase material induced by helium irradiation and evolution with a sequence of different helium irradiation doses of 5E15, 1E16, 5E16 and 1E17cm-2 at room temperature (RT) were characterized with grazing incidence X-ray diffraction (GIXRD) and Raman spectra analysis. The irradiation damage process of Ti3SiC2 can be roughly divided into three stages according to the level of helium irradiation dose: (1) for a low damage dose, only crystal and damaged Ti3SiC2 exit; (2) at a higher irradiation dose, there is some damaged TiC phase additionally; (3) with a much higher irradiation dose, crystal TiC phase could be found inside the samples as well. Moreover, the 450C 5E16cm-2 helium irradiation on Ti3SiC2 has confirmed that Ti3SiC2 has much higher irradiation tolerance at higher temperature, which implies that Ti3SiC2 could be a potential future structural and fuel coating material working at high temperature environments.

Published
2020
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19. Helium effects and bubbles formation in irradiated Ti3SiC2

Author

Zhang, Hongliang, Su, Ranran, Szlufarska, Izabela, Shi, Liqun, and Wen, Haiming

Subjects
Condensed Matter - Materials Science
Abstract

Ti3SiC2 is a potential structural material for nuclear reactor applications. However, He irradiation effects in this material are not well understood, especially at high temperatures. Here, we compare the effects of He irradiation in Ti3SiC2 at room temperature (RT) and at 750 {\deg}C. Irradiation at 750 {\deg}C was found to lead to extremely elongated He bubbles that are concentrated in the nano-laminate layers of Ti3SiC2, whereas the overall crystal structure of the material remained intact. In contrast, at RT, the layered structure was significantly damaged and highly disordered after irradiation. Our study reveals that at elevated temperatures, the unique structure of Ti3SiC2 can accommodate large amounts of He atoms in the nano-laminate layer, without compromising the structural stability of the material. The structure and the mechanical tests results show that the irradiation induced swelling and hardening at 750 {\deg}C are much smaller than those at RT. These results indicate that Ti3SiC2 has an excellent resistance to accumulation of radiation-induced He impurities and that it has a considerable tolerance to irradiation-induced degradation of mechanical properties at high temperatures.

Published
2020
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33. A high-entropy alloy with hierarchical nanoprecipitates and ultrahigh strength.

Author

Fu, Zhiqiang, Jiang, Lin, Wardini, Jenna L, MacDonald, Benjamin E, Wen, Haiming, Xiong, Wei, Zhang, Dalong, Zhou, Yizhang, Rupert, Timothy J, Chen, Weiping, and Lavernia, Enrique J

Abstract

High-entropy alloys (HEAs) are a class of metallic materials that have revolutionized alloy design. They are known for their high compressive strengths, often greater than 1 GPa; however, the tensile strengths of most reported HEAs are limited. Here, we report a strategy for the design and fabrication of HEAs that can achieve ultrahigh tensile strengths. The proposed strategy involves the introduction of a high density of hierarchical intragranular nanoprecipitates. To establish the validity of this strategy, we designed and fabricated a bulk Fe25Co25Ni25Al10Ti15 HEA to consist of a principal face-centered cubic (fcc) phase containing hierarchical intragranular nanoprecipitates. Our results show that precipitation strengthening, as one of the main strengthening mechanisms, contributes to a tensile yield strength (σ0.2) of ~1.86 GPa and an ultimate tensile strength of ~2.52 GPa at room temperature, which heretofore represents the highest strength reported for an HEA with an appreciable failure strain of ~5.2%.

Published
2018

37. Microstructural evolution in a precipitate-hardened (Fe0.3Ni0.3Mn0.3Cr0.1)94Ti2Al4 multi-principal element alloy during high-pressure torsion.

Author

Luebbe, Matthew, Duan, Jiaqi, Cao, Peipei, Lu, Zhaoping, Islamgaliev, Rinat K., Valiev, Ruslan Z., Liu, Yuzi, and Wen, Haiming

Subjects
TRACE elements, NUCLEAR reactor materials, TORSION, ALLOYS, STRAIN hardening, IRON-manganese alloys, HEAT treatment, TRANSMISSION electron microscopy
Abstract

Multi-principal element alloys demonstrate high strength, thermal stability, and irradiation resistance, making them excellent candidate materials for applications in nuclear reactors and other harsh environments. Some studies have examined the use of high-pressure torsion to strengthen MPEAs through grain size reduction and strain hardening. However, no studies have investigated the effect of HPT on secondary phases (precipitates) within an MPEA. Two alloys, (Fe0.3Ni0.3Mn0.3Cr0.1)94Ti2Al4 containing Ni(Ti, Al) B2 phase, and CrFe σ phase, and single-phase Fe0.3Ni0.3Mn0.3Cr0.1, were fabricated by casting and heat treatment. Both alloys were then processed with HPT to study microstructural evolution. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the alloys before and after HPT processing. HPT processing produced a nanocrystalline structure in both alloys, but (Fe0.3Ni0.3Mn0.3Cr0.1)94Ti2Al4 exhibited a significantly smaller grain size and higher dislocation density than Fe0.3Ni0.3Mn0.3Cr0.1, with corresponding higher hardness. Before HPT, the (Fe0.3Ni0.3Mn0.3Cr0.1)94Ti2Al4 alloy consisted of large grain (~ 400 μm) and precipitates, including B2 of ~ 38 μm average size, B2 of ~ 0.7 μm average size, and small amounts of σ of ~ 1.5 µm average size. After HPT, the larger B2 precipitates were decreased in size and volume fraction, while the smaller B2 precipitates were completely dissolved; the σ precipitates appeared unaffected by HPT, likely due to their much higher hardness. Observation of the B2 precipitate distribution along radial distance indicates that the strain caused the precipitates to fracture at intermediate strain (γ = 125) and dissolve at high strain (γ = 280). [ABSTRACT FROM AUTHOR]

Published
2024
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40. Design of an all-weather water extraction system based on solar energy and diurnal temperature difference

Author

Zhang Chengran, Pu Liangyu, Bai Weihan, Guo Tianyuan, and Wen Haiming

Subjects
Environmental sciences, GE1-350
Abstract

According to the survey, the water content in the air is as high as 14,000 km3. To make full use of the moisture retained in the air, we designed this all-weather water extraction system based on solar energy and the temperature difference between day and night. The system uses solar power panels to supply power to the micro-suction fan during the daytime, builds a condensation structure of “air-ground”, and uses the natural temperature difference between day and night to condense water at night and store it in the buried water reservoir. Semi-arid areas have water demand and have the advantages of all-weather use, fast water extraction, low cost, and ease of promotion.

Published
2023
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