Influence of limiting the actuation strain on the functional fatigue behavior of Ni 50.3 Ti 29.7 Hf 20 high temperature shape memory alloy

The cyclic stability and the fatigue life of NiTiHf alloys are very important for their functionality at high temperatures. The previous studies have shown that the increase in Upper Cycle Temperature (UCT) and the magnitude of applied stress decreased the cyclic stability and fatigue life of NiTiHf...

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Bibliographic Details
Published in:Journal of intelligent material systems and structures 2021-01, Vol.32 (2), p.219-227
Main Authors: Tugrul, H Onat, Saygili, Hasan H, Kockar, Benat
Format: Article
Language:English
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Summary:The cyclic stability and the fatigue life of NiTiHf alloys are very important for their functionality at high temperatures. The previous studies have shown that the increase in Upper Cycle Temperature (UCT) and the magnitude of applied stress decreased the cyclic stability and fatigue life of NiTiHf high temperature shape memory alloys due to plasticity with dislocation formation at high temperature. On the other hand, this study was dedicated to the effect of limited actuation strain against the applied constant stress to the functional fatigue life and the possible damage mechanism such as dislocation and crack formation. Strain limitation led to observe insignificant amount of accumulated irrecoverable strain but significant amount of crack formation such that the reason of the failure of Ni 50.3 Ti 29.7 Hf 20 (at%) alloy was found to be the crack formation instead of dislocation accumulation.
ISSN:1045-389X
1530-8138
DOI:10.1177/1045389X20953610