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23. Effects of powder feeding rate on porosity and tensile strength of powder feeding laser welded Al-30wt.% B4C composite with the addition of Al powder.

Author

Li, Yunjiang, Le, Guomin, Pang, Xiaoxuan, Luo, Jinru, Cai, Jiqing, and Zhang, Pengcheng

Subjects
LASER welding, X-ray computed microtomography, TENSILE strength, NEUTRON capture, POROSITY, METALLIC composites, POWDERS
Abstract

Al-B4C metal matrix composite is an advanced neutron absorption material. In order to obtain a wider application in spent nuclear fuel storage and transport, the welding technique is essential for Al-B4C composites. In this paper, powder feeding laser welding (PFLW) method was used to weld Al-30wt.% B4C composite. During the experiments, Al powder was used as the filler metal, the effects of powder feeding rate on porosity, neutron shielding ratio and tensile strength of the joints were investigated by using micro-CT (micro computed tomography), OM, SEM and TEM. It is found that PFLW has a significant weld porosity suppression effect, and a joint efficiency (UTS) of 87% is obtained in PFLW of Al-30wt.% B4C composite with the powder feeding rate of 1.2 g/min. The neutron shielding ratio of the joint reduced by 3% due to the volume ratio of AlB12C2 (a B-rich reaction product) reduced by 7.6% when the powder feeding rate is 1.2 g/min. The results illustrate the great potential of PFLW in welding Al-B4C composites. [ABSTRACT FROM AUTHOR]

Published
2023
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24. Microstructural investigations on laser welded Al-30wt.% B4C composite.

Author

Li, Yunjiang, Le, Guomin, Zhang, Pengcheng, Xian, Yajiang, Hu, Zuqi, and Pang, Xiaoxuan

Subjects
LASER welding, CHEMICAL reactions, BRITTLE fractures, WELDING, WELDING equipment, RIVETED joints, ALUMINUM composites
Abstract

In order to tailor the microstructures and mechanical properties of laser welded Al-B4C composite, it is necessary to elucidate the chemical reactions between B4C reinforcement and Al matrix during laser welding process. In this study, 3 mm thick Al-30wt.% B4C plates were laser welded using different parameters. Then the microstructure, reaction products, tensile properties and fracture surface of welded joint were studied. The results show that the reaction products of the weld zone can be controlled by varying the welding energy input, but the full penetration welded joint requires high energy input (120 KJ/m in this paper). For the full penetration welded joint, all B4C particles and part Al matrix react to form irregularly particle-like AlB2C2 and coarse needle-like Al4C3 phases, the joint efficiency is 67%. The failure mechanism of AlB12C2 is cleavage fracture, and the failure mechanism of Al4C3 is interfacial decohesion and pull out. The interfacial decohesion between Al4C3 and Al matrix results in crack initiation due to their weak bonding interface. The cracks propagate, connect and penetrate the brittle AlB12C2 phase and eventually lead to brittle fracture of the joint. [ABSTRACT FROM AUTHOR]

Published
2023
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44. Influences of contents and reaction of carbon and oxygen on microstructure and mechanical properties of sintered 93W-4.6Ni-1.9Fe-0.5Co alloys

Author

Yang Xiaofeng, Le Guomin, Li Qiang, and Fan Hui

Subjects
Materials science, Metallurgy, General Engineering, Oxide, chemistry.chemical_element, Sintering, Deoxidization, Tungsten, Microstructure, Oxygen, Carbide, chemistry.chemical_compound, chemistry, Carbon
Abstract

Several 93W-4.6Ni-1.9Fe-0.5Co alloys have been prepared by liquid phase sintering in vacuum atmosphere using powders with different contents of carbon and oxygen. The microstructures and mechanical properties of sintered samples have been investigated. Results show that the carbon in the starting powders has a stronger deoxidization ability in the high temperature vacuum sintering process due to the carbon-oxygen reaction, which decreases the contents of carbon and oxygen in the sintered samples and prevents the formation of carbide and oxide inclusions, resulting in a strong interfacial boundary between tungsten and bonding phase. The mechanical properties are improved significantly when the oxygen content is controlled to be lower than 500 μg/g.

45. Microstructure evolution and mechanical properties of AlxCoCrFeNi high-entropy alloys by laser melting deposition.

Author

Huang, Liufei, Sun, Yaoning, Amar, Abdukadir, Wu, Changgui, Liu, Xue, Le, Guomin, Wang, Xiaoying, Wu, Jian, Li, Kun, Jiang, Chunli, and Li, Jinfeng

Subjects
*LASER deposition, *SOLUTION strengthening, *MICROSTRUCTURE, *ENTROPY, *ALLOYS
Abstract

Al x CoCrFeNi (x = 0, 0.2, 0.45, 0.7 and 1) high entropy alloys (HEAs) have been successfully synthesized by laser melting deposition (LMD). It is found that the microstructure of LMD-CoCrFeNi HEA with increasing the content of Al has been transformed from a single face-centered cubic (FCC) phase to mixture of FCC + BCC duplex phases, and then to body-centered cubic (BCC/B2) phases. The addition of Al (Al 0.2 , Al 0.45 and Al 0.7) remarkably improved the yield strength σ 0.2 (from 138 MPa to 185 MPa, 262 MPa and 771 MPa) and the tensile strength σ t (from 634 MPa to 675 MPa, 863 MPa and 1171 MPa) of the samples, with the prize of plasticity decrease from 46% to 45%, 41% and 11% in tension. This work provides an approach of LMD-fabricated CoCrFeNi-based HEAs with different Al addition to accommodate the microstructure and mechanical properties, and insights into the correlation of mechanical properties with the solid solution strengthening or/and the precipitation of hardening phase. • Al x CoCrFeNi (x = 0, 0.2, 0.45, 0.7 and 1) HEAs have been prepared by LMD method. • The ΔH mix and VEC are used to predict the phase stability for LMD-fabricated HEAs. • The LMD HEA has been changed from a single FCC phase to BCC phase via Al addition. • With the increase of Al amount, σ 0.2 and σ t of the HEAs under the tensile and compression test have been obvious improved. [ABSTRACT FROM AUTHOR]

Published
2021
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