|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Fatigue in Materials: Fundamentals, Multiscale Modeling and Prevention
||Grain Size and Texture Effects on Fatigue Cracking in NiTi Shape Memory Alloys
||William LePage, Aslan Ahadi, William Lenthe, Qingping Sun, Tresa Pollock, John Shaw, Samantha Daly
|On-Site Speaker (Planned)
The grain size (GS) and crystallographic dependence of fatigue cracking in the shape memory alloy NiTi was experimentally characterized using a multi-scale experimental framework combining in-situ scanning electron microscopy, digital image correlation (DIC), and a high-precision external SEM scan controller. The coarse-grained (GS 1500 nm) sample's higher crack opening level (2.4 - 3.2 MPa√m) corresponded to a higher fatigue threshold (2.4 MPa√m). All other specimens (GS 10 - 80 nm) exhibited lower crack opening levels (< 0.8 MPa√m) and lower fatigue thresholds (1.9 MPa√m). A non-monotonic trend with respect to GS was observed in crack growth rates for ΔK ≥ 6 MPa√m, where the 42 and 80 nm samples had the fastest crack growth rates, and 10 and 18 nm samples had intermediate rates. Experiments were also performed with varied crack growth direction with respect to crystallographic texture, and these results are discussed with respect to microstructural observations via TEM.
||Planned: Supplemental Proceedings volume