Low temperature in-situ micro-compression testing of iron pillars

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• 作者：A.B. Hagen ; ^{anette.b.hagen@ntnu.no" class="auth_mail" title="E-mail the corresponding author} ; C. Thaulow
• 关键词：Bcc iron ; Pillar compression testing ; Slip systems ; Temperature dependency ; Orientation dependency ; Molecular dynamics simulations
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：15 December 2016
• 年：2016
• 卷：678
• 期：Complete
• 页码：355-364
• 全文大小：1537 K

文摘

An in-situ nanomechanical cooling system has been developed to study the temperature dependency of local mechanical properties and slip behavior of bcc α-Fe. Uniaxial compression tests with Focused Ion Beam (FIB) fabricated pillars with a diameter of 1 &micro;m, were performed in the single slip orientations inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0035.gif">iner hidden">$\left[\overline{2}35\right]$ and inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0036.gif">iner hidden">$\left[\overline{1}49\right]$ at room temperature and 198 K. The testing was conducted inside a Scanning Electron Microscope (SEM) equipped with a nanoindenter. Slip trace analyses revealed occurrence of slip in the {112}<111> family of slip systems for inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0037.gif">iner hidden">$\left[\overline{2}35\right]$ pillars at both room temperature and 198 K while the predominantly slip systems governing the deformation on inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0038.gif">iner hidden">$\left[\overline{1}49\right]$ pillars were {110}<111> for both test temperatures. The stress-strain response showed an increased strength with decreasing temperature for the inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0039.gif">iner hidden">$\left[\overline{2}35\right]$ pillars, in contrast to inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0040.gif">iner hidden">$\left[\overline{1}49\right]$ pillars, where only a weak temperature dependence is observed. Furthermore, for inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0041.gif">iner hidden">$\left[\overline{2}35\right]$ pillars, the appearance of slip is less prominent at 198 K, indicating that the temperature strongly influences the relative motion of screw and edge dislocations. Molecular Dynamics (MD) simulations performed at 15 K and 300 K, was used to study dislocation mechanisms for the two orientations. inlineImage" height="19" width="33" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S092150931631190X-si0042.gif">iner hidden">$\left[\overline{1}49\right]$ pillars exhibit a change in deformation mechanisms at low temperature and the evolution of dislocation density during deformation, display distinct differences for the two loading orientations.