Study of the fracture mechanism of Nb_SS/Nb₅Si₃ in situ composite: Based on a mechanical characterization of interfacial strength

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• 作者：Kai Guan ; Lina Jia ; ^{jialina@buaa.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Bin Kong ; Sainan Yuan ; Hu Zhang
• 关键词：Nanoindentation ; Finite element method ; Intermetallics ; Interfaces ; Fracture
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：29 April 2016
• 年：2016
• 卷：663
• 期：Complete
• 页码：98-107
• 全文大小：4564 K

文摘

The reinforcement/matrix interfaces in Nb-Si based in situ composites play a crucial role as the medium of load transfer in determining the overall mechanical performance. Especially during the fracture process, whether the interfaces are stronger or weaker than the matrix or reinforcement phase usually dominates the fracture behavior. In this work, the mechanical properties of Nb_SS/Nb₅Si₃ interface in Nb-15Si-24Ti-4Cr-2Al-2Hf (at%) alloy were characterized by a hybrid method of nanoindentations and finite element analysis. As a consequence, the interfacial shear strength τ₀, interfacial normal strength σ₀ and the interfacial fracture energy Γ_n of Nb_SS/Nb₅Si₃ interfaces between the (002)_α-Nb5Si3//(002)_NbSS and [310] _α-Nb5Si3//[110]_NbSS have been evaluated to be 300±20 MPa, 800±50 MPa and 3±0.5 J m^−2 respectively. According to the characterized interfacial properties, the fracture behavior of this alloy was further discussed. By comparing the fracture morphology of the composite with the characterized interfacial strength, the possible fracture process can be deduced and described as the sequence of phase boundary, brittle Nb₅Si₃ and ductile Nb_SS.