About this Abstract |
Meeting |
2020 TMS Annual Meeting & Exhibition
|
Symposium
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Fatigue in Materials: Fundamentals, Multiscale Characterizations and Computational Modeling
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Presentation Title |
G-17: Deformation Mechanism of Nickel-titanium-hafnium Alloys Subjected to Rolling Contact Fatigue Experiments |
Author(s) |
Behnam Aminahmadi, Sean Mills, Christopher Dellacorte, Ronald D. Noebe, Aaron P. Stebner |
On-Site Speaker (Planned) |
Sean Mills |
Abstract Scope |
High hardness and compressive elastic strength of Ni-rich, ternary Ni-Ti-Hf alloys make them attractive candidates for space-age bearing applications since they provide comparable resistance as tool steels to degradation and wear under rolling contact fatigue (RCF) conditions, with superior corrosion and dent damage resistance. Bearing element performance of Ni-Ti-Hf alloys is enhanced by inducing alternative strengthening pathways through complex precipitation sequences, which are dramatically different from that in binary NiTi alloys. In Ni56Ti36Hf8 alloy, new Ni16Ti11 and H-phase precipitates form homogeneously leading to superior hardness (769 HV) and yield stress (3.4 GPa) compared to Ni55Ti45 alloy. Using high-resolution transmission electron microscopy techniques, deformed regions under RCF wear tracks show amorphous bands of nanoscale width in the fatigue condition, eventually leading to fully amorphized regions in the spalled condition. These detailed microstructure attributes are correlated with RCF performance (hardness, strength, life), to provide better understanding of NiTi and NiTiHf bearing alloys |
Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |