Effect of Heat Treatment on the Structural Properties and Martensitic Transformation of Ni-26.5at. %Ta High Temperature Shape Memory Alloy

The effect of heat treatment at 450 oC, 550 oC and 650 oC temperatures for 1 hour on the structural properties and the transformation behaviour of Ni-26.5at. %Ta high temperature shape memory alloy have been examined by XRD, SEM-EDX analysis and DSC measurements. The SEM-EDX investigations showed that microstructures of all heat-treated alloy samples consisted of Ta-rich NiTa2 precipitate phase and matrix. The XRD results indicated that both numbers and intensities of martensite phase reflections of the alloy highly increased as a result of heat treatment at 650 oC. This was indication that the structural properties of the alloy were significantly affected by heat treatment at 650 oC. The thermal measurements revealed that the high temperature shape memory behaviour of the alloy did not changed with heat treatment. However, it was seen that heat treatment performed at 450 oC caused shifting martensitic transformation temperatures of the alloy and hence transformation hysteresis value of the alloy increased.

___

  • Referans1 Firstov, G.S., Van Humbeeck, J. and Koval, Y.N., “High-temperature shape memory alloys: Some recent developments”, Mater. Sci. Eng. A, 378: 2-10, (2004).
  • Referans2 Gama, J.L.L., Dantas, C.C., Quadros, N.F., Ferreira, R.A.S. and Yadava, Y.P., “Microstructure-mechanical property relationship to copper alloys with shape memory during thermomechanical treatments”, Metall. Mater. Trans. A, 37A: 77-87, (2006).
  • Referans3 Celik, H., Aldirmaz, E. and Aksoy, I., “Effects of deformation on microstructure of Cu-Zn-Ni alloy”, GU J. Sci., 25: 337-342, (2012).
  • Referans4 Firstov, G.S., Koval, Yu.N., Van Humbeeck, J. and Ochin, P., “Martensitic transformation and shape memory effect in Ni3Ta: A novel high-temperature shape memory alloy”, Mater. Sci. Eng. A, 481-482: 590-593, (2008).
  • Referans5 Rudajevová, A. and Pospíšil, J., “Shape memory behavior of a Ni3Ta alloy pre-deformed in compression”, Mater. Sci. Eng. A, 527: 2900-2905, (2010).
  • Referans6 Biffi, C.A., Agresti, F., Casati, R. and Tuissi, A., “Ni3Ta high temperature shape memory alloys: effect of B addition on the martensitic transformation and microstructure”, Mater. Today: Proceedings, 2S: S813-S816, (2015).
  • Referans7 Kosorukova, T.A., Firstov, G.S., Koval, Yu.N., Van Humbeeck, J. and Zhuravlev, B., “Phase transformations and shape memory behavior in Ni3Ta-based intermetallics”, Mater. Today: Proceedings, 2S: S793-S796, (2015).
  • Referans8 Yildiz, K., “Thermally induced martensitic transformation and structural properties in Ni-Ta high temperature shape memory alloys”, Eur. Phys. J. Plus., 134: 11, (2019).
  • Referans9 Chen, H.R., Shape Memory Alloys: Manufacture, Properties and Applications, Nova Science Publishers, New York, (2010).
  • Referans10 Kosorukova, T., Firstov, G., Noël, H. and Ivanchenko, V., “Crystal structure changes in the Ni3Ta intermetallic compound”, Chem. Met. Alloys., 6: 196-199, (2013).