Microstructural Characteristics and Mechanical Properties of a Nb/Nb5Si3 based Composite with and without Directional Solidification

Advanced Composites Letters

Article

J.T. Guo¹  L.Y. Sheng²  Y.X. Tian³ 

[1] Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China;Shenzhen Institute, Peking University, Shenzhen 518057, China;The Central Institute of Baosteel Group Co., LTD, Shanghai, 200122, China;

关键词: Nb/NbSi composite;    Directional solidification;    Microstructure;    Mechanical properties;   

DOI  :  10.1177/096369351802700405

 received in 2018-06-20, accepted in 2018-08-10,  发布年份 2018

来源: Sage Journals

【 摘 要 】

The Nb/Nb5Si3 based composites were fabricated by conventional casting (CC) and directional solidification (DS) methods. Micro structural characteristics, compressive properties and fracture toughness of the CC and DS composites were investigated by SEM, XRD, TEM, bending and compression tests. The results demonstrate that in the CC Nb/Nb5Si3 based composite, the intergrowth of fine (Nb,Ti)ss and α-(Nb,Ti)5Si3 phases leads to the formation of eutectic structure and the coarse α-(Nb,Ti)5Si3 dendritic phase prefers to grow along eutectic cell boundary. The (Nb,Ti)3Si, (Ti,Nb)5Si3 and Dy2O3 phases mainly segregate along the eutectic cell boundary and moreover there is an orientation relationship between the (Nb,Ti)3Si and (Nb,Ti)ss phases: [001] (Nb,Ti)3Si//[112](Nb,Ti)ss and (110)(Nb,Ti)3Si//(110)(Nb,Ti)ss. The DS processing promotes the formation of coarse primary α-(Nb,Ti)5Si3 phase, (Ti,Nb)5Si3/(Nb,Ti)ss eutectic and α-(Nb,Ti)5Si3/(Nb,Ti)ss eutectic in the DS Nb/Nb5Si3 based composite. Moreover, the (Nb,Ti)ss and α-(Nb,Ti)5Si3 phases are aligned paralleling to the DS direction and exhibits strong crystal orientation preference. In addition, an orientation relationship between the (Nb,Ti) ss and α-(Nb,Ti)5Si3 phases is observed: [310]α(Nb,Ti)5Si3//[110](Nb,Ti)ss. Compared with the CC Nb/Nb5Si3 based composite, the DS Nb/Nb5Si3 based composite possesses the higher yield strength and fracture toughness, which should be ascribed to the microstructure optimization.

【 授权许可】

Unknown   
© 2018 SAGE Publications Ltd

【 图 表 】

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