High Temperature Structural MaterialsNo Access

EFFECT OF Si ON MICROSTRUCTURE AND FRACTURE TOUGHNESS OF DIRECTIONALLY SOLIDIFIED Nb SILICIDE ALLOYS

School of Mechanical Science and Engineering, Beihang University, Xueyuan Road, Haidian District BeijingCity, 100191, China

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YUYE WANG

School of Mechanical Science and Engineering, Beihang University, Xueyuan Road, Haidian District BeijingCity, 100191, China

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SHUSUO LI

School of Mechanical Science and Engineering, Beihang University, Xueyuan Road, Haidian District BeijingCity, 100191, China

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LIWU JIANG

School of Mechanical Science and Engineering, Beihang University, Xueyuan Road, Haidian District BeijingCity, 100191, China

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, and

YAFANG HAN

School of Mechanical Science and Engineering, Beihang University, Xueyuan Road, Haidian District BeijingCity, 100191, China

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https://doi.org/10.1142/S0217979210065933Cited by:10 (Source: Crossref)

Abstract

Nb-xSi(x=3,9,16)-22Ti-3Cr-3Al-2Hf (at.%) have been successfully prepared by directional solidification in an optical floating zone furnace. Microstructure analysis and phases identification of the alloys were examined by X-ray diffraction (XRD), Electro Probe Micro Analyzer (EPMA) and Energy Disperse Spectroscopy (EDS). Fracture toughness specimens without pre-crack were prepared, room temperature fracture toughness of alloys was tested by three-point bending method, and fracture mechanism was studied. The results showed that with increasing Si content, Nb₅Si₃ phase gradually increased and the phase transformed from γ-Nb₅Si₃ to the stable α-Nb₅Si₃ phase and β-Nb₅Si₃ phase. There appeared the Ti-rich Nb₅Si₃ phase when the Si content is 16 at%. In addition, more micro-cracks generated in the Ti-rich Nb₅Si₃ phase, which seriously affected room temperature fracture toughness of the alloys.

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