Phase Transformation in Ni-Ti Shape Memory and Superelastic Alloys Subjected to High Pressure Torsion

Article Preview

Abstract:

A systematic study on the phase transformation of Ni-Ti shape memory and superelastic alloys subjected to Severe Plastic Deformation (SPD) – High Pressure Torsion (HPT) technique has been carried out. Ni-Ti alloys of three compositions were chosen for the study. Specimens of these alloys in as-received (AR) condition and after HPT have been subjected to Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) analyses. In this study, while comparing the results of DSC thermograms and XRD spectra for the same sample conditions, some differences were observed. In the case of NiTi-H alloy after HPT, there appeared one stage phase transformation with DSC both while heating and cooling suggesting Martensite↔Austenite transformation but, with respect to XRD spectra while cooling, at the intermediate temperature of 55°C, the R-phase peaks corresponding to (1 1 2)R and (3 0 0)R planes appeared. In the thermogram obtained for the NiTi-B alloy subjected to HPT, it is observed that, while cooling, the Austenite to R-phase transformation is merged with R-phase to Martensite transformation. The results of the XRD obtained at -180°C show the presence of R-phase along with M-phase. The DSC curve of the NiTi-S alloy subjected to HPT corresponds to one stage phase transformation both while heating and cooling but, the diffractogram of the sample obtained at -180°C corresponds to the presence of both R-phase and M-phase.

You might also be interested in these eBooks

Info:

Periodical:

Advanced Materials Research (Volumes 123-125)

Pages:

1007-1010

Citation:

Online since:

August 2010

Export:

Price:

[1] T. Tadaki, K. Otsuka and K. Shimizu: Ann. Rev. Mater. Sci. Vol. 25-45 (1989), p.25.

Google Scholar

[2] Jan Van Humbeeck: Adv. Eng. Mater. Vol. 3 (2001), p.837.

Google Scholar

[3] K. Otsuka and X. Ren: Prog. Mater. Sci. Vol. 50 (2005), p.511.

Google Scholar

[4] H.C. Lin, S.K. Wu, T.S. Chou and H.P. Kao: Acta Metall. Mater. Vol. 39 (1991), p. (2069).

Google Scholar

[5] K.W.K. Yeung, C.Y. Chung, K.M.C. Cheung, W.W. Lu and K.D.K. Luk: Mater. Sci. Forum Vol. 394-395 (2002), p.321.

Google Scholar

[6] A.S. Paula, K.K. Mahesh and F.M. Braz Fernandes: Eur. Phys. J. - Special Topics Vol. 158 (2008), p.45.

Google Scholar

[7] R.Z. Valiev, R.K. Islamgaliev and I.V. Alexandrov: Prog. Mater. Sci. Vol. 45 (2000), p.103.

Google Scholar

[8] Z. Li, X. Cheng and Q. ShangGuan: Mater. Lett. Vol. 59 (2005), p.705.

Google Scholar

[9] V.G. Pushin, A.V. Korolev, N.I. Kourov, D.V. Gunderov, R.Z. Vliev, V.V. Koledov and V.G. Shavrov: Mater. Sci. Forum Vol. 503-504 (2006), p.545.

DOI: 10.4028/www.scientific.net/msf.503-504.545

Google Scholar

[10] X.D. Wu, J.S. Wu and Z. Wang: Smart Mater. Struct. Vol. 8 (1999), p.574.

Google Scholar

[11] K. Gall, K. Juntuneni, H.J. Maier, H. Sehitoglu and Y.I. Chumlyakov: Acta Mater. Vol. 49 (2001), p.3205.

Google Scholar

[12] T. Goryczka and H. Morawiec: J. Alloy Compd. Vol. 367 (2004), p.137.

Google Scholar

[13] J. Uchil, F.M. Braz Fernandes and K.K. Mahesh: Mater. Charact. Vol. 58 (2007), p.243.

Google Scholar

[14] F.M. Braz Fernandes, K.K. Mahesh, R. J. C. Silva, C. Gurau and G. Gurau: Phys. Status Solidi (2010), in press.

DOI: 10.1002/pssc.200983371

Google Scholar