Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films

SCRIPTA MATERIALIA

卷:191

Article

Bakhit, Babak¹  Palisaitis, Justinas¹  Wu, Zhengtao²  Sortica, Mauricio A.³  Primetzhofer, Daniel³  Persson, Per O. A.¹  Rosen, Johanna¹  Hultman, Lars¹  Petrov, Ivan^1,4,5,6  Greene, J. E.^1,4,5,6  Greczynski, Grzegorz¹ 

[1] Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden

[2] Guangdong Univ Technol, Sch Electromech Engn, Guangzhou 510006, Peoples R China

[3] Uppsala Univ, Dept Phys & Astron, Appl Nucl Phys, SE-75120 Uppsala, Sweden

[4] Univ Illinois, Mat Res Lab, Urbana, IL 61801 USA

[5] Univ Illinois, Dept Mat Sci, Urbana, IL 61801 USA

[6] Natl Taiwan Univ Sci & Technol, Dept Mat Sci & Engn, Taipei 10607, Taiwan

关键词: Thin films;    Transition-metal (TM) diborides;    Age hardening;    Thermal stability;    Hardness and elastic modulus;   

DOI  :  10.1016/j.scriptamat.2020.09.026

来源: Elsevier

【 摘 要 】

We recently showed that sputter-deposited Zr1-xTaxBy thin films have hexagonal AlB2-type columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x >= 0.2. As-deposited layers with x >= 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we study the mechanical properties of ZrB2.4, Zr0.8Ta0.2B1.8, and Zr0.7Ta0.3B1.5 films annealed in Ar atmosphere as a function of annealing temperature T-a up to 1200 degrees C. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to T-a = 800 degrees C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5 +/- 1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at T-a > 800 degrees C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire T-a range. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd.

【 授权许可】

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