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Microstructure and property of Ti2AlNb alloy by selective electron beam melting |
Qianying CHE1, Weiwei HE1,2,*( ), Huixia LI1, Kangkang CHENG1, Yu WANG1 |
1 Xi'an Sailong Metal Materials Co., Ltd., Xi'an 710018, China 2 State Key Laboratory for Porous Metals Materials, Northwest Institute for Nonferrous Metal Research, Xi'an 710016, China |
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Abstract Ti2AlNb based alloys is considered to be the most potential material material to replace the traditional Ni-based superalloys, because of its excellent high-temperature specific strength, creep resistance and high fracture toughness. Ti-22Al-25Nb alloy was fabricated by selective electron beam melting(SEBM), and the density of as-built samples reached 5.42-5.43 g/cm3through process optimization. The microstructure, phase evolution and mechanical property of the as-built and HIPed Ti2AlNb alloy samples were investigated. The results show that the microstructure of the as-built and HIPed samples both show the columnar crystalline structures along the deposition direction, which are all composed of B2, O and α2 phases, and the amount of O/α2 phase gradually increases from top to bottom. After HIP, the width and amount of the O/α2 phase are reduced and relatively uniform when compared with that of the as-built samples. In the bottom area, the microhardness of the as-built sample exhibits higher value of about (345.87±5.09)HV, while the hardness increases to 388.91-390.48HV after HIP. The ultimate tensile strength and elongation of the as-built sample at room temperature are (1061±23.71) MPa and (3.67±1.15)% respectively, and the ultimate tensile strength increases to (1101±23.07) MPa and the elongation reduces to 3.5% after HIP.
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Received: 28 September 2021
Published: 18 July 2022
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Corresponding Authors:
Weiwei HE
E-mail: hewi126@126.com
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Material | Mass fraction/% | Al | Fe | Nb | O | C | H | N | Ti | Powder | 11.24 | 0.06 | 43.80 | 0.038 | 0.015 | 0.0007 | 0.003 | Bal | As-built rods | 10.04 | 0.06 | 44.08 | 0.041 | 0.016 | 0.0007 | 0.003 | Bal |
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Chemical compositions of the Ti-22Al-25Nb powder and as-built rods
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Morphology of Ti-22Al-25Nb powder
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Photograph of the Ti2AlNb samples by SEBM (a), schematic diagram of microscopic tissue sampling at different heights (b) and tensile samples (c)
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Processing window for fabricating Ti2AlNb alloy by SEBM
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Effect of line energy density on the relative density of the samples
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Microstructures of as-built (1) and HIP (2) Ti2AlNb alloy at different heights (a)sample 1;(b)sample 2;(c)sample 3;(d)sample 4;(e)sample 5
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SEM images of as-built (a) and HIP (b) Ti2AlNb alloy
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XRD patterns of as-built (a) and HIP (b) samples at different heights
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Microhardness of as-built and HIP samples at different heights
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Tensile properties of the Ti2AlNb alloys at room temperature
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SEM morphologies of fracture surface (a)as-built; (b)HIP
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