Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1580061 | Materials Science and Engineering: A | 2009 | 4 Pages |
Abstract
The temperature dependence of the Young's modulus and of the internal friction (IF) has been investigated between 80 and 300 K at acoustical frequencies in the hexagonal (C14) Laves-phase TiCr1.78 charged with hydrogen. In this compound H occupies tetrahedral interstitial sites which are grouped in interlinked hexagons. A mechanical relaxation has been found at around 120 K (f = 5.4 kHz), which appears to be due to tunnelling transitions of delocalized H from one hexagon to the other. The rate of H absorption has been investigated at high temperature (660-1200 K) and the H diffusion coefficient has been derived from the pressure measurement as a function of time. A cumulative Arrhenius plot of IF and absorption diffusion data exhibits a non-exponential behaviour, which is due to a change in the diffusion mechanism from over-barrier hopping at high temperature to phonon-assisted tunnelling at low temperature.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
G. Mazzolai, B. Coluzzi, A. Biscarini, F.M. Mazzolai, A. Tuissi, F. Agresti, G. Principi, S. Lo Russo,