About this Abstract |
Meeting |
MS&T21: Materials Science & Technology
|
Symposium
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Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales III
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Presentation Title |
Yield Point Phenomena in Single Crystal BCC and FCC Metals |
Author(s) |
David T. Fullwood, Josh Tsai, Tristan Russell, Guowei Zhou, Robert H Wagoner, Eric R Homer |
On-Site Speaker (Planned) |
David T. Fullwood |
Abstract Scope |
Yield point phenomena (YPP) are often attributed to locking of dislocations by atmospheres of interstitials, or are related to the increased stress required to nucleated dislocations relative to the subsequent stress required to move them. The orientation dependence of YPP has been observed previously, but not necessarily fully explained. We observe YPP in high-purity single crystal tantalum (BCC) and nickel (FCC) for a range of orientations. An Schmid factor-based activity index is defined to capture the number of slip system likely to be operating. The magnitude of YPP shows a linear correlation with this activity index. Furthermore, a general mesoscale (GM) model that incorporates internal stress generation into a standard crystal plasticity (CP) model, predicts the observations without any fitting to the experimental data (beyond the standard CP hardening parameters). The results point to a role for internal stress evolution in YPP and hardening stagnation for some materials. |