Journal of Alloys and Compounds 403 (2005) 154–160
Damping characteristics of a Ti
40.5
Ni
49.5
Zr
10
shape memory alloy
S.F. Hsieh
a, S.K. Wu
b,∗aDepartment of Mold and Die Engineering, National Kaohsiung University of Applied Science, Kaohsiung, Taiwan 807, Republic of China bDepartment of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China
Received 12 April 2005; accepted 27 April 2005 Available online 14 July 2005
Abstract
Ti40.5Ni49.5Zr10alloy undergoes B2↔ B19martensitic transformation. Damping capacities of B19and B2 phases of this alloy are lower
than those of Ti51Ni49alloy due to Zr atoms solid-soluted hardening. Transformation temperatures of this alloy decrease, but transformation
peak heightsQ−1maxincrease with increasing aging time at 300◦C due to the formation of finer (0 0 1)Mtwins for specimens aged longer. The
Q−1
maxpeaks of the slightly cold-rolled Ti40.5Ni49.5Zr10alloy are higher than those of the as-annealed alloy, which may be because the thinner
twins are induced by small deformation. © 2005 Elsevier B.V. All rights reserved.
Keywords: Shape memory alloy; Damping capacity; Martensitic transformation; Aging; Cold-rolling
1. Introduction
Near-equiatomic TiNi shape memory alloys (SMAs) are technologically important due to their superior shape memory effect and superelastic properties. However, the applications of these alloys are limited to use at temperatures lower than 100◦C because their starting temperatures of martensitic transformation, Ms, are usually lower than 60◦C. High temperature SMAs with Ms temperatures higher than 100◦C have been exhaustively researched due to their many potential applications. In particular, the TiNiZr and TiNiHf ternary high temperature SMAs have been developed with high Ms temperatures[1–3].
In addition to shape memory effect and superelastic properties, TiNi SMAs have also been found to exhibit high mechanical damping capacity [4]. Damping mecha-nisms, in general, involve the stress-induced movement of defects. For high-damping metals, the major mechanisms are either stress-induced movement of dislocations or planar defects [5], and most of these mechanisms can be phenomenologically split into three classes: dynamic
∗Corresponding author. Tel.: +886 2 2363 7846; fax: +886 2 2363 4562.
E-mail address: [email protected] (S.K. Wu).
hysteresis, static hysteresis and transformation mechanisms. Dynamic hysteresis is produced by stress-aided ordering of defects overcoming local barriers by thermal activation and it yields damping that is frequency-dependent and amplitude-independent. Static hysteresis appears due to the stress-induced ‘unpinning’ or ‘break-away’ process of the defects [5–7] and it yields damping that is frequency-independent and amplitude-dependent. Some metals exhibit a high level of damping in the transformation region, for example, thermoelastic martensitic transformation of SMAs [8,9]. Such thermoelastic damping is frequently amplitude-independent and is proportional to the transformation rate. In the present study, the characteristics of internal friction (IF) in a Ti40.5Ni49.5Zr10SMA are investigated. In addition, the effect of aging and cold-rolling on the damping capacity of this alloy is also discussed.
2. Experimental procedure
The conventional tungsten arc melting technique was employed to prepare Ti40.5Ni49.5Zr10 (in at.%) alloy. Tita-nium (purity 99.7 wt.%), nickel (purity 99.9 wt.%) and zirco-nium (purity 99.8 wt.%), totaling about 120 g, were melted and remelted at least six times in an argon atmosphere. A 0925-8388/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
S.F. Hsieh, S.K. Wu / Journal of Alloys and Compounds 403 (2005) 154–160 159
binary alloys is the0 1 1 type II twin[26]which is also their lattice invariant shear (LIS). However, it has been proved that the (0 0 1) compound twin is the LIS of Ti42.2Ni49.8Hf8and Ti36.5Ni48.5Hf15alloys[3,27]. FromFig. 5, the (0 0 1)Mtwin planes are more dense in the 300◦C×240 h aged specimen, but (1 0 0)M twin planes are more dense in the as-annealed one. These results indicate that the0 1 1 type II and (1 0 0)M twins can evolve to (0 0 1)Mtwins in the aged Ti40.5Ni49.5Zr10 alloy. Hence, the higher peakQ−1maxand the smaller width W of the longer aged Ti40.5Ni49.5Zr10specimen are attributable to stress-assisted twin-boundary motions of the abundant (0 0 1)M twins. The behaviors of these IF peaks associ-ated with martensitic transformation agree with Delorme’s model.
The asymmetric transformation peaks of IF test shown in Figs.2(b) and3(b) are similar to those of the DSC measure-ment shown inFig. 1(a and b). We propose that the IF peaks smoothing from low-temperature side are closely related to the stored elastic energy associated with martensitic trans-formation, which is the same reason for the asymmetric DSC peaks discussed in Section3.1.
4.3. Internal friction in cold-rolled Ti40.5Ni49.5Zr10alloy
Based on the vibration theory[28], the reduction in the specimen thickness will decrease the natural frequency of the specimen under the same amplitude when the specimen’s length and width are kept constant. Therefore, the frequency f should decrease when the specimen is slightly cold-rolled (5% thickness reduction), as compared with Figs.2(a) and 6(a). At the same time, the IF peakQ−1maxof the 5% cold-rolled specimen is higher than that of the as-annealed one. Lin et al.[17]reported that the light cold-rolling (≤5% thickness reduction) of Ti50Ni50 binary alloy increases the Q−1max of transformation peaks. Dalle et al.[3]reported that (0 0 1)M twinning in the 6.7% deformed Ti42.2Ni49.8Hf8specimen is thinner than that in the undeformed one, where the small deformation is accommodated by (0 0 1)Mtwinning and the further deformation is accommodated by the detwinning of these micro-twins. We suggest that the same phenomenon can also be found in the slightly cold-rolled Ti40.5Ni49.5Zr10 alloy. Hence, the higher Q−1max of the slightly cold-rolled Ti40.5Ni49.5Zr10 alloy shown in Fig. 6(b) than that of the as-annealed alloy shown in Fig. 2(b) is attributable to the thinner (0 0 1)Mtwins induced by small deformation, which are suggested to be easier to accommodate.
5. Conclusion
1. The as-annealed Ti40.5Ni49.5Zr10 alloy undergoes one-stage B2↔ B19 martensitic transformation. Damping capacities of B19 and B2 phases of this alloy are lower than those of Ti51Ni49alloy due to Zr atoms solid-soluted hardening.
2. With increasing aging time at 300◦C, the transformation peak heightQ−1maxincreases, but transformation tempera-ture decreases. These characteristics are closely related to the aging effects on the formation of finer (0 0 1)Mtwins for specimens aged longer.
3. The degree of martensite stabilization of Ti40.5Ni49.5Zr10 alloy is larger than that of Ti50Ni50 alloy for the same 5% cold-rolling because the former has a higher inher-ent hardness than the latter. The higher peakQ−1maxof the slightly deformed Ti40.5Ni49.5Zr10alloy compared to the as-annealed one is attributable to the thinner (0 0 1)Mtwins induced by small deformation.
Acknowledgements
The authors are pleased to acknowledge the financial sup-port of this research by the National Science Council (NSC), Republic of China under Grants NSC 93-2216-E002-003 and NSC 93-2216-E151-017.
References
[1] J.H. Mulder, J.H. Mass, J. Beyer, ICOMAT (1992) 869–874. [2] S.F. Hsieh, S.K. Wu, J. Alloys Compd. 266 (1998) 276–282. [3] F. Dalle, E. Perrin, P. Vermaut, M. Masse, R. Portier, Acta Mater.
50 (2002) 3557–3565.
[4] O. Mercier, K.N. Melton, Y. De Preville, Acta Metall. 27 (1979) 1467–1475.
[5] I.G. Ritchie, Z.-L. Pan, Metall. Trans. 22A (1991) 607–616. [6] R. De Batist, Internal Friction of Structural Defects in Crystalline
Solids, North-Holland Publishing Co., Amsterdam, 1972. [7] D.W. James, Mater. Sci. Eng. 4 (1969) 1–8.
[8] R. De Batist, J. Phys. (1983) C9–C39.
[9] J. Van Humbeck, Proceedings of The ASM Materials Week and TMS/AIME Fall Meeting, Role of Interfaces on Materials Damping, ASM, Materials Park, OH, 1985, pp. 5–24.
[10] P.L. Potapov, R. Gotthardt, L. Bataillard, Phys. Stat. Sol. 165 (1998) 401–408.
[11] H.C. Lin, S.K. Wu, J.C. Lin, Mater. Chem. Phys. 37 (1994) 184– 190.
[12] K. Iwasaki, R. Hasiguti, Trans. JIM 28 (1987) 363–367.
[13] H.C. Lin, S.K. Wu, T.S. Chou, J. Alloys Compd. 355 (2003) 90– 96.
[14] S.F. Hsieh, S.K. Wu, J. Alloys Compd. 270 (1998) 237–241. [15] R. Santamarta, C. Segui, J. Pons, E. Cesari, Scr. Mater. 41 (1999)
867–872.
[16] X.D. Han, W.H. Zou, R. Wang, Z. Zhang, D.Z. Yang, K.H. Wu, J. De Phys. IV (1995), C8-73-C758.
[17] H.C. Lin, S.K. Wu, T.S. Chou, H.P. Kao, Acta Metall. 39 (1991) 2069–2080.
[18] T. Onda, Y. Bando, T. Ohba, K. Otsuka, Mater. Trans., JIM 33 (1992) 354–359.
[19] S. Miyazaki, C.M. Wayman, Acta Metall. 36 (1988) 181– 192.
[20] H.C. Lin, S.K. Wu, M.T. Yeh, Metall. Trans. 24A (1993) 2189– 2194.
[21] A.I. Lotkov, A.V. Kuznetsov, V.N. Griskov, A.A. Botaki, in: Y. Chu, T.Y. Hsu, T. Ko (Eds.), Proceedings of International Shape Memory Alloy Symposium, China Academic Publishers, Guilin, China, 1986, pp. 153–158.
160 S.F. Hsieh, S.K. Wu / Journal of Alloys and Compounds 403 (2005) 154–160
[22] O. Mercier, K.N. Melton, G. Gremaud, J. Hagi, J. Appl. Phys. 41 (1980) 1833–1834.
[23] H.C. Lin, S.K. Wu, Y.C. Chang, Metall. Trans. 26A (1995) 851–858. [24] J.F. Delorme, R. Schmid, M. Robin, P. Gobin, J. Phys. C2 (1971)
101–109.
[25] W. Dejonghe, R. de Batist, L. Delaey, Scr. Metall. 10 (1976) 1125–1128.
[26] M. Nishida, H. Ohgi, I. Itai, A. Chiba, K. Yamauchi, Acta Mater. 43 (1995) 1229–1234.
[27] X.D. Han, W.H. Zou, R. Wang, Z. Zhang, D.Z. Yang, Acta Mater. 44 (1996) 3711–3721.
[28] B.H. Tongue, Principles of Vibration, second ed., Oxford University Press, Oxford, 2002, pp. 17–18.
