In-situ formation of NbC in nanocrystalline Cu

JOURNAL OF ALLOYS AND COMPOUNDS

卷:725

Article

Zeng, Wei^1,4  Xie, Jingwen¹  Zhou, Dengshan^2,3  Fu, Zhiqiang⁴  Zhang, Deliang^1,2,3  Lavernia, Enrique J.⁴ 

[1] Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China

[2] Northeastern Univ, Sch Mat Sci & Engn, Minist Educ, Key Lab Anisotropy & Texture Mat, Shenyang 110819, Liaoning, Peoples R China

[3] Northeastern Univ, Sch Mat Sci & Engn, Inst Ceram & Powder Met, Shenyang 110819, Liaoning, Peoples R China

[4] Univ Calif Irvine, Dept Chem Engn & Mat Sci, Irvine, CA 92607 USA

关键词: In-situ formation;    NbC nanoparticles;    Nanocrystalline copper;    High strength;   

DOI  :  10.1016/j.jallcom.2017.07.179

来源: Elsevier

【 摘 要 】

We report on an investigation of the in-situ formation of NbC nanoparticles in a Cu nanocrystalline matrix, paying particular attention to the role played by NbC on stabilizing and strengthening the matrix. The material was prepared by milling a Cu-5wt% Nb powder mixture with 1 wt% stearic acid for 36 h, followed by annealing of the milled powder at temperatures ranging from 400 to 1000 degrees C. Our results show that the NbC nucleates at an approximate temperature of 700 degrees C and that the associated enthalpy of formation and activation energy of NbC are approximately -0.8 kJ/mol and + 312 kJ/mol, respectively. Moreover, the initial size of NbC particles formed at 700 degrees C was 8 nm, and showed limited coarsening (to 21 nm) even when annealed at 1000 degrees C for 1 h. With the presence of NbC, dislocation annihilation was impaired and grain boundary mobility was hindered, resulting in a dislocation density as high as 10(14) m(-2) following annealing at 1000 degrees C, and a grain size of 96 nm after annealing at 900 degrees C. The high thermal stability of NbC nanoparticles and the Cu matrix lead to appreciable strengthening of the composite powders as evidenced by a microhardness increase from 2128 MPa for the as-milled powder to 2665 MPa for the powder annealed at 700 degrees C for 1 h. (C) 2017 Elsevier B.V. All rights reserved.

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