首页|(162953)Ternary relation among stacking fault energy, grain size and twin nucleation size in nanocrystalline and ultrafine grained CuAl alloys
(162953)Ternary relation among stacking fault energy, grain size and twin nucleation size in nanocrystalline and ultrafine grained CuAl alloys
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NSTL
Elsevier
The stacking fault energy y of an alloy has been reported to significantly affect the grain size d and twin nucleation size r_c during grain refinement. However, ternary relation among y, d and r_c has not been investigated comprehensively. Here we prepared nanocrystalline (NC) and ultrafine-grained (UFG) 99.99 wt% Cu, Cu-0.86 wt% Al and Cu-2.2 wt% Al alloys with different y by high-pressure torsion (HPT), and then characterized d and r_c. Transmission electron microscopy observations show that under the same experimental condition d decreases and corresponding grain refinement mechanism transforms from dislocation subdivision to twin segmentation with decreasing y. The relation among y, d and r_c from experiments are consistent well with theoretical prediction from Meyers model. r_c decreases with decreasing d, and the variation is exacerbated by the decrease of y. r_c increases first and then decreases by forming a peak-shaped variation with decreasing y when d is in UFG regime, suggesting there exists an optimum stacking fault energy r_c for twin nucleation. The r_c peak becomes flat and moves to higher y value when d is in NC regime due to the enhanced geometric effect of d on r_c which weakens the role of y. Our findings reveal a comprehensive ternary relationship among y, d and r_c, and provide guidance for designing NC and UFG materials with high-density twins and good strength-ductility combination.
Stacking fault energyGrain sizeTwin nucleation sizeCu and Cu-Al alloysHigh-pressure torsion
Shaojia Shi、Liangjuan Dai、Yonghao Zhao
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State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jinlin University, Changchun 130012, China
Nano and Heterogeneous Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
NSTL
Elsevier
