Researchers from the University of Kentucky and University of Arkansas discussed the effects of palladium on NiTiHf shape memory alloys at MS&T 2019 in Portland, Oregon.
Binary NiTi alloys have already gained immense popularity in the biomedical industry. However, they possess some limitations, such as low strength and transformation temperature, which have constrained their implementation in many other potential applications.
The addition of ternary hafnium has been proven to be very effective in improving the strength and raising the transformation temperature of conventional NiTi. However, high strength NiTiHf alloys exhibit high brittleness and low transformation strain.
On the other hand, our studies showed that the addition of even minor amounts of palladium (3-5 at. %) could overcome these drawbacks. In the current study, two different compositions: Ni47.3-Ti29.7-Hf20-Pd3 and Ni43.3-Ti31.7-Hf20-Pd5 (at. %) were investigated.
Following a systematic aging study, we characterized transformation temperature, microstructure, and shape-memory response of the alloys. Both were found to show a beneficial combination of high transformation temperatures, strain recovery, strength, and ductility.
Paper Title: Effects of Pd Addition to High Strength NiTiHf Shape Memory Alloys
Authors: Guher Toker, Haluk Karaca, University of Kentucky
Soheil Saedi, Dipak Banerjee, University of Arkansas at Little Rock
