The internal friction (IF) and Young’s modulus of the Ni50.8Ti49.2 shape memory alloy have been measured as a function of temperature (130 K < T < 335 K) by a dynamic mechanical analyser at various strain amplitudes and frequencies. Besides the one associated with the austenite/martensite transformation, several other IF peaks have been observed both in the hydrogen-free and in the hydrogen-doped states of the material. Some of these peaks are non-thermally activated processes caused by stress-assisted hysteretic motions of twin boundaries and dislocations; some others represent thermally activated relaxations caused by reorientation of hydrogen elastic dipoles or by stress-induced motions of twin boundaries interacting with hydrogen. The present low-frequency measurements provide new information concerning the amplitude and frequency dependences of the damping processes, thus throwing new light on their structural mechanisms.

Low-frequency internal friction of hydrogen-free and hydrogen-doped NiTi alloys.

MAZZOLAI, Fabio Massimo;BISCARINI, Andrea;COLUZZI, Bruno;
2007

Abstract

The internal friction (IF) and Young’s modulus of the Ni50.8Ti49.2 shape memory alloy have been measured as a function of temperature (130 K < T < 335 K) by a dynamic mechanical analyser at various strain amplitudes and frequencies. Besides the one associated with the austenite/martensite transformation, several other IF peaks have been observed both in the hydrogen-free and in the hydrogen-doped states of the material. Some of these peaks are non-thermally activated processes caused by stress-assisted hysteretic motions of twin boundaries and dislocations; some others represent thermally activated relaxations caused by reorientation of hydrogen elastic dipoles or by stress-induced motions of twin boundaries interacting with hydrogen. The present low-frequency measurements provide new information concerning the amplitude and frequency dependences of the damping processes, thus throwing new light on their structural mechanisms.
2007
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/150864
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 56
  • ???jsp.display-item.citation.isi??? 52
social impact