Effect of Aging Treatment on Phase Transformation of a Pseudoelastic NiTi Alloy

Abstract:

The pseudoelasticity (PE) and shape memory effect (SME) are the two main behaviors presented by the shape memory alloys (SMA's) and are associated respectively to mechanical and thermally induced martensitic transformations. The aim of this work is to investigate the effects of heat treatment temperature on the microstructure properties and phase transformation temperatures of a NiTi alloy with 57 w.t. % Ni. The X-ray diffraction (XRD) was carried out to obtain the phases present. The phase transformation temperatures were measured by differential scanning calorimetry (DSC). The alloy chemical composition and hardness were obtained by X-ray fluorescence (XRF), hardness (HRC) and microhardness (HV) tests, respectively. The analysis were performed in the state as received and after aging treatment at different temperatures between 350 °C and 600°C. The samples as received contained a fully austenitic microstructure at room temperature and the DSC analysis showed the presence of a phase transformation in multiple steps (B19'-R-B2). After aging at 350 °C the R phase was observed at room temperature with the austenite. With the aging treatment at 600 °C the R phase was solubilized and the alloy phase transformation occurred in a single step, ie, direct transformation from austenite to martensite and vice versa. The transformation temperatures Af, As, Ms and Mf changed with the aging treatment temperatures.

• Periodical: Advanced Materials Research (Volume 936)
• Pages: 1216-1223
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.936.1216
• Online since: June 2014
• Authors: Palloma Viera Muterlle*, Eduard Benavides Villamarin, Paulo Herrera, Edson Paulo da Silva
• Keywords: Heat Treatment, NiTi, Phase Transformation, Pseudoelasticity, R-Phase, Shape Memory Alloy (SMA)

References

[1] Otsuka, K. and Wayman, C.M., (1998). Shape memory materials, Cambridge University Press. Cambridge.

[2] Moringa, M., KATO, M., Kamimura, T., Fukumoto, M., Harada, I. and Kubu, K. Theoretical design of ß type titanium alloys, Titanium '92, Science and Technology, The Minerals, Metals & Material Society, (1993).

[3] Gil, F.J. and Pl, J.A. Shape memory alloys for medical applications, Proc Instn Mech Engr Vol 212 Part H, (1998).

[4] Otsuka, K. and Ren, X., Physical Metallurgy of NiTi-based Shape Memory Alloys, Progress in Materials Science, 50 (2005)511.

DOI: 10.1016/j.pmatsci.2004.10.001

[5] MATHEUS, T.C. Efeito do teor de carbono e da qualidade superficial na vida em fadiga de fios de Ni-Ti visando aplicações endodônticas. 139p -Tese de doutorado, Instituto Militar de Engenharia, Rio de Janeiro, (2008).

DOI: 10.36229/978-85-7042-207-1.cap.19

[6] Magela , J.O.; Silva, M.I.N.; Ribeiro, G.M. and AndradeE, M.S. Electrical Resistivity and DSC measurements of phase transformation temperatures in Ni-Ti shape memory alloys. In: 11th International Conference on Advanced Materials, 2009, Rio de Janeiro. 11th ICAM, (2009).

[7] MAGELA, J.O. Influência de tratamentos térmicos e mecânicos nas temperaturas de transformação martensítica em ligas Ni-Ti com efeito memória de forma. 126p –Dissertação Mestrado, Universidade Federal de Ouro Preto, Ouro Preto, (2010).

DOI: 10.26678/abcm.conem2018.con18-1599

[8] Santos, C.M. L, Ligas Ni-Ti ricas em Ni Tratamento térmico, Termomecânico e Efeito de micromemória de forma, 2006, 156p. Tese ( Doutorado em Ciência dos Materiais) - Instituto Militar de Engenharia, Rio de Janeiro.

DOI: 10.26678/abcm.conem2018.con18-1599