{'fraction_non_alphanumeric': 0.023809523809523808, 'fraction_numerical': 0.023166023166023165, 'mean_word_length': 4.475352112676056, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Effect of hydrogen on the damping properties of NiTi alloys

The effect of hydrogen dopings on the internal friction and the Young's modulus has been investigated in the alloys Ni 50.8 Ti 49.2 , Ni 49 Ti 51 and Ni 40 Ti 50 Cu 10 as a function of the hydrogen content n H (n H =H/Me atomic) and frequency. It has been found that hydrogen strongly affects the anelastic spectrum of these alloys in the temperature domain. The IF peak occurring at the austenite-martensite (A-M) transition in the solubilized Ni 50.8 Ti 49.2 alloy is enhanced by hydrogen at low contents (n H 1.3). An additional IF peak is introduced in the same alloy by H for n H >1.3. This second peak, which appears at temperatures higher than the martensite start temperature M s , is likely due to hydrogen re-distributions over subsets of interstitial sites within a hydride, under the applied alternating stress fields associated with the sample vibrations. The relaxation parameters of this peak, which is thermally activated, are in keeping with the expectations from H diffusion high temperature data. In the aged alloy Ni 49 Ti 51 H suppresses the low temperature IF background and introduces a thermally activated relaxation, which is associated with H dragging processes by twin boundaries. A relaxation effect, again ascribable to H dragging processes by twin boundaries, has also been evidenced with the Ni 40 Ti 50 Cu 10 alloy. The most remarkable result of these investigations is the fact that hydrogen appears to be a very sensitive tool to probe twin boundary dynamics.