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Delayed plasticity during spherical nanoindentation of an iron-chromium-aluminum alloy: Effect of ferric ion irradiation
Y Zhang a , 1 , C W Li b , 1 , J L Jiang c , J F Gu b , ∗, H. Wang d , ∗, Y D Jia a , G Wang a , X G An e , Q Wang a , c , ∗, J Lu c
a Institute of Materials, Shanghai University, Shanghai 20 0 072, China
b School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
c Department of Mechanical Engineering, City University of Hong Kong, Kowloon, SAR, China
d Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu 610041, China
e Interdisciplinary Materials Research Center, Institute for Advanced Study, Chengdu University, Chengdu, 610106, China
Abstract:
Spherical nanoindentation of an iron-chromium-aluminum alloy was conducted to study the effect of ferric-ion (Fe 3 + ) irradiation on the time-dependent plasticity behavior in the surface layers of this alloy. It was observed that the initiation of plasticity by the appearance of displacement burst or “pop-in” event occurred after a period of waiting time in the apparent elastic regime and that Fe 3 + irradiation at 360 °C and up to ∼0.5 displacements per atom could make it happen under the lower applied loads but with a reduced magnitude. Through the experimental data, an activation volume and activation energy were extracted for the delayed plasticity. The results show that Fe 3 + -irradiation significantly reduced its acti- vation volume from ∼3.05 b 3 to ∼1.75 b 3 (where b = Burgers vector), but slightly increased its activation energy from ∼0.65 to ∼0.71 eV. On the other hand, high-resolution scanning transmission electron mi- croscopy observations reveal that the irradiation at the elevated temperature created interstitial atom pair onto the (100) habit plane that can serve as the nucleation site of a 100 dislocation loop while elim- inating the pre-existing dislocations. Consequently, it is indicated that heterogeneous nucleation of the dislocation loop was predominant in the delayed plasticity initiation of this alloy and that the nucleation of the interstitial-type dislocation loop was involved due to Fe 3 + -irradiation.
Delayed plasticity during spherical nanoindentation of an iron-chromium-aluminum alloy: Effect of ferric ion irradiation.pdf
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