ISIS Neutron and Muon Source Data Journal

In-situ Neutron Diffraction Investigation of the Effects of Hf and Nb Additions to NiTi Shape Memory Alloys under Compressive Loading for Elastocaloric Refrigeration

Abstract: Elastocaloric Refrigeration demands advanced SMAs with elevated transformation temperatures and improved fatigue resistance. Conventional NiTi SMAs exhibit desirable elastocaloric performance but are limited by low transformation temperatures and functional fatigue from accumulated microplasticity and microstructural changes. Tenary NiTi-based alloys like NiTiHf and NiTiNb can overcome these limits by raising transformation temperatures and widening thermal hysteresis, though at the cost of reduced ductility and complex microstructures(e.g. Hf-induced lattice distortions, Nb-rich precipitates). To harness their potential for elastocaloric refrigeration, a deeper in-situ understanding of their phase transformation and internal stress evolution under load is needed. In this study, we intend to employ in-situ neutron diffraction on high-flux Engin-X beamline to probe NiTiHf and NiTiNb alloys under cyclic compressive loading. Stepwise loading and unloading sequences with real-time diffraction capture the evolution of phase fractions and lattice strains through each mechanical cycle. Key objectives include determining the transformation start/finish stresses and strain hysteresis in each alloy, identifying any retained austenite or secondary phases, and assessing how Hf and Nb alloying affects precipitate formation and long-term cyclic stability. These experiments will yield detailed phase stress-strain relationships that elucidate how alloying alters elastocaloric performance.

Principal Investigator: Dr Mubarak Abdelrasoul Elnour Ismail
Experimenter: Professor Saurav Goel
Experimenter: Prof (Assoc.) Alex Paurine
Local Contact: Dr Tung Lik Lee
Experimenter: Dr Kevin O'Toole
Experimenter: Dr Jan Pilch
Experimenter: Dr David Vokoun

DOI: 10.5286/ISIS.E.RB2610228

ISIS Experiment Number: RB2610228

Publisher: STFC ISIS Neutron and Muon Source

Data format: RAW/Nexus
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Data Citation

The recommended format for citing this dataset in a research publication is as:
[author], [date], [title], [publisher], [doi]

For Example:
Dr Mubarak Abdelrasoul Elnour Ismail et al; (2026): In-situ Neutron Diffraction Investigation of the Effects of Hf and Nb Additions to NiTi Shape Memory Alloys under Compressive Loading for Elastocaloric Refrigeration, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2610228

Data is released under the CC-BY-4.0 license.