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118 results on '"Mazzolai, F.M."'

7. Effect of H-doping on damping capacity of various NiTi-based alloys at kHz frequencies

Author

Coluzzi, A., Biscarini, A., Mazzolai, G., Mazzolai, F.M., and Tuissi, A.

Subjects
Titanium alloys -- Electric properties, Nickel alloys -- Electric properties, Damping (Mechanics) -- Analysis, Hydrogen -- Electric properties, Nickel-titanium alloys -- Electric properties, Semiconductors -- Impurity distribution, Semiconductors -- Methods, Science and technology
Abstract

The effect of H doping in combination with various thermomechanical treatments given to materials, in order to identify conditions for maximum efficiency in the conversion of mechanical energy into heat at around room temperature was studied. It was observed that for appropriate alloy composition, the peaks occur at around room temperature (for acoustical frequencies), providing an opportunity to reduce machinery vibrations and noise pollutions.

Published
2006

24. Effect of H-doping on damping capacity of various NiTi-based alloys at kHz frequencies

Author

Coluzzi B., Biscarini A., Mazzolai G., Mazzolai F.M., and Tuissi A.

Abstract

The internal friction Q-1 and the Young's modulus E of NiTi based alloys have been measured as a function of temperature after various thermomechanical and hydrogen-doping treatments given to the materials. Hydrogen is found to play a major role introducing tall damping peaks associated with Snoek-type and H-twin boundary relaxations. Levels of Q-1 as high as 0.08 have been detected, which are among the highest to date measured in metal alloy systems. For appropriate alloy compositions, these peaks occur at around room temperature (for acoustical frequencies), thus providing a good opportunity to reduce machinery vibrations and noise pollution. In the paper, the conditions are highlighted under which maximum efficiency can be reached in the conversion of mechanical energy into heat

Published
2006

26. Damping spectrum of H-free and H-doped shape momory alloys NiTiHfCu at KHz frequencies

Author

Coluzzi B., Biscarini A., Mazzolai G., Mazzolai F.M., and Tuissi A.

Subjects
Hydrogen diffusion, Shape memory alloys, Martensitic transition, Mechanical relaxation
Abstract

The internal friction, the Young's modulus and the heat flow have been measured as a function of temperature in the Ni47Ti40Hf10Cu3 alloy. H-doping introduces two anelastic relaxations PH and PH0 . PH is a Snoek-type effect (WH 1?4 0:60 ? 0:1 eV, s0H 1?4 2 ? 10?ð16?1Þ s) also occurring in NiTi(Cu) alloys. PH0 is a new phenomenon due to quantum-mechanical transitions of H bound to Hf atoms and located at tetrahedral interstitial sites.

Published
2004

27. Internal friction spectra of the Ni40Ti50Cu10 shape memory alloy charged with hydrogen

Author

Mazzolai F.M.(a), Biscarini A.(a), Campanella R.(a), Coluzzi B(a)., Mazzolai G.(a), Rotini A.(a), and Tuissi A.(b)

Subjects
Shape memory, Hydrides, Acoustic methods, NiTiCu alloys, Phase transformation
Abstract

The temperature dependence of the dynamic Young's modulus E, the elastic energy dissipation coefficient Q-1 and the heat flow (DSC) has been studied between 90 and 370 K in an Ni40Ti50Cu10 alloy containing various amounts nH of H (nH=H/Me=0; 0.004; 0.008; 0.013 and 0.018 at.). The Youngfs modulus exhibits softening when the start temperature Ms of the B2¨B19 martensitic transition is approached on cooling and a much steeper modulus decrease between Ms and Mf. This steep decrease appears to be associated with stress-induced motions of twin boundaries within the B19 martensite as it is drastically reduced by H pinning of these boundaries. No internal friction (IF) peak occurs at the B2-B19 transition and the values of Q-1 are high in the B19 martensite (100x10-4). Two IF peaks, PH and PTWH, occur below Ms in the H-doped material; the first is likely due to stress-assisted reordering of H elastic dipoles within a hydride phase, the second to H dragging processes by twin boundaries.

Published
2003

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