Martensite Transformation and Superelasticity at High Temperature of (TiHfZr)74(NbTa)26 High-Entropy Shape Memory Alloy

Abstract

In this work, a (TiHfZr)(NbTa) 26 (%at) highentropy quinary alloy has been developed especially for high-temperature superelastic applications and studied over a large range of temperatures. The mechanical properties of this new material were compared with those of other superelastic alloys. The different ingots have been made in a cold crucible from pure metals. Several thermomechanical treatments have been performed on the microstructure of four alloys among them (TiHfZr)(NbTa) 26 alloy. The microstructure of each alloy has been characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and x-ray diffraction technique (XRD) and the mechanical behavior was investigated through three-point bending tests between -40 and 200 °C, in quasi-static monotonic and low cycle loading conditions. The effects of the thermomechanical treatments on the static and cyclic thermomechanical mechanical responses have been analyzed in combination with the microstructure investigations of the four studied alloys. It has been shown that the (TiHfZr)(NbTa) 26 alloy presents a martensitic transformation and a superelastic effect over the studied range of temperatures, in the cold-worked state or after solution treatment. Finally, the obtained experimental results have been compared with those of other superelastic alloys demonstrating the features of the developed highentropy high-temperature superelastic alloy.

Relationship between Chemical Composition and Ms Temperature in High-Entropy Shape Memory Alloys

“…( 7) for NiTi-like and TiNb-like alloys. These two alloys have been chosen according to the different criteria proposed in [13] and [19]. The two alloys have been heat-treated to be homogenized and solutioned.…”

“…The M s temperatures of the other studied HE-SMAs are summarized in Table 1. It is important to emphasize that the whole HE-SMAs presented in the database have different types and different chemical compositions: NiTi-like [5,[11][12][13][14][15][16][17][18], TiNb-like [19], NiAl-like [20,21], CuAl-like [22] and FeAl-like [23,24]. In addition, it should be noted that all the alloys selected to enrich the database, either specifically developed for the study or taken from the open literature, are in the same metallurgical state (Solution Treatment or ST).…”

Medical high-entropy alloy: Outstanding mechanical properties and superb biological compatibility

“…Some bio-HEAs have also been shown to have superelastic properties. Peltier ( Peltier et al, 2021 ) pointed out that for (TiHfZr) 74 (NbTa) 26 , its superelasticity originates from the transition of β↔α” when deformation occurs. The superelastic temperature range is 40–200°C, which is compatible with the human service environment temperature.…”

On the Sintering Behavior of Nb2O5 and Ta2O5 Mixed Oxide Powders

“…Binary alloys of niobium and tantalum can serve as anticorrosion coatings (for CoCr alloys in the biomedical industry) [ 15 ] in the fabrication of high-entropy shape memory and superconducting alloys [ 16 , 17 , 18 ]. These applications employ a melting-cum-remelting process to make a homogeneous alloy from which the components are fabricated.…”