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Strengthening effect of blocky phases and γ/γ interface in the directionally solidified high-Nb-containing TiAl alloy

Herein, a TiAl alloy containing a high Nb concentration with a composition of Ti-45.5Al-7Nb-(W, Cr, B) was prepared by electromagnetic cold crucible zone melting (ECCZM) using a ceramic mould. The microstructure, tensile properties and fracture morphology were analyzed by means of SEM, EDS and TEM....

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2022-09, Vol.853, p.143792, Article 143792
Main Authors: Huang, Haitao, Ding, Hongsheng, Xu, Xuesong, Zhang, Xuxing, Chen, Ruirun, Guo, Jingjie, Fu, Hengzhi
Format: Article
Language:English
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Summary:Herein, a TiAl alloy containing a high Nb concentration with a composition of Ti-45.5Al-7Nb-(W, Cr, B) was prepared by electromagnetic cold crucible zone melting (ECCZM) using a ceramic mould. The microstructure, tensile properties and fracture morphology were analyzed by means of SEM, EDS and TEM. As results, there were three blocky phases, namely α2b, γb, and TiB, and two types of γ/γ interfaces. The tensile tests at room temperature showed that the ultimate tensile strength of the alloy reached a maximum value of 645 MPa. The primary strengthening mechanism of the alloy was the interfacial strengthening of the γ/γ interfaces. The two types of γ/γ interfaces can hinder dislocation movement and allow the dislocations to move under high tensile stress, thus strengthening the alloy without increasing stress concentration. Moreover, the three blocky phases can hinder dislocations through the interface between them and γ lamellae, thereby strengthening the lamellae. Among them the γb phase plays a coordinated role in controlling the deformation of the lamellar colony.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2022.143792