Effect of Mn content on microstructure and transformation behavior of TiZrHfNiCoCu multi-component high-entropy shape memory alloys.

Multi-component Ti 16.667 Zr 16.667 Hf 16.667 Ni 25 Co 10 Cu 15-X Mn X at.% (X = 0, 1, 3, 5 and 7) high-entropy shape memory alloys (HESMAs) were prepared by arc-melting and then microstructures, transformation temperatures, phase constituents and superelastic properties were investigated by scanning electron microscope observation, differential scanning calorimetery, X-ray diffraction and dynamic mechanical analysis in tensile mode, respectively. The microstructure of solution-treated TiZrHfNiCoCuMn HESMAs specimens consisted of (NiCoCuMn)-rich matrix, (TiZrHf) 2 (NiCoCuMn)-type phase and (TiZrHf)(NiCoCuMn)-type phase. The area fraction of (TiZrHf) 2 (NiCoCuMn)-type phase increased from 1.7 to 5.1% with increasing Mn content from 0 to 7 at.%. The area fraction of the (TiZrHf)(NiCoCuMn)-type phase increased from 1.9 to 17.2% with increasing Mn content from 3 to 7 at.%. -ΔH mix effect was dominant over ΔS mix and δ effects for phase constitution in TiZrHfNiCoCuMn HESMAs. The martensitic transformation start temperature decreased with the addition of Mn content up to 3 at.% and then increased with increasing Mn content from 3 at.% to 7 at.%. TiZrHfNiCoCuMn HESMAs showed clear superelasticity and the total recovered strain decreased with increasing Mn content. • Multi-component Ti 16.667 Zr 16.667 Hf 16.667 Ni 25 Co 10 Cu 15-X Mn X at.% (X = 0, 1, 3, 5 and 7) high-entropy shape memory alloys (HESMAs) were designed. • This work provided theoretical and experimental information for the phase selection in high entropy shape memory alloys. • -ΔH mix is dominant over ΔS mix and δ for phase constitution in present studied HESMAs. [ABSTRACT FROM AUTHOR]