Temperature-dependent plastic hysteresis in highly confined polycrystalline Nb films. (5th January 2018)

• Record Type: Journal Article
• Authors: Waheed, S; Hao, R; Zheng, Z; Wheeler, J M; Michler, J; Balint, D S; Giuliani, F
• Is Part Of: Modelling and simulation in materials science and engineering. Volume 26:Number 2(2018)
• Publication Date: 2018-01-05
• Subjects: discrete dislocation plasticity -- temperature -- BCC -- plastic hysteresis -- cyclic deformation; Materials -- Mathematical models -- Periodicals; Matériaux -- Modèles mathématiques -- Périodiques; Materials -- Mathematical models; Periodicals; 620.00113
• DOI: 10.1088/1361-651X/aa9ba2
• Languages: English
• ISSNs: 0965-0393

Abstract

Abstract: In this study, the effect of temperature on the cyclic deformation behaviour of a confined polycrystalline Nb film is investigated. Micropillars encapsulating a thin niobium interlayer are deformed under cyclic axial compression at different test temperatures. A distinct plastic hysteresis is observed for samples tested at elevated temperatures, whereas negligible plastic hysteresis is observed for samples tested at room temperature. These results are interpreted using planar discrete dislocation plasticity incorporating slip transmission across grain boundaries. The effect of temperature-dependent grain boundary energy and dislocation mobility on dislocation penetration and, consequently, the size of plastic hysteresis is simulated to correlate with the experimental results. It is found that the decrease in grain boundary energy barrier caused by the increase in temperature does not lead to any appreciable change in the cyclic response. However, dislocation mobility significantly affects the size of plastic hysteresis, with high mobilities leading to a larger hysteresis. Therefore, it is postulated that the experimental observations are predominantly caused by an increase in dislocation mobility as the temperature is increased above the critical temperature of body-centred cubic niobium.