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Recently, doctor student Yumei Zhou and her co-workers
found the ambient-temperature high damping material:
Ti-45Pd-5Cr martensitic alloy. Basis on this work, the
paper titled as "High damping capacity in a wide
ambient-temperature range in hydrogen-doped and hydrogen-free
Ti-45Pd-5Cr martensitic alloy" is now published
in Scripta Materialia.
High damping alloys are attracting keen attention
from an environmental viewpoint and almost all applications
requires high damping capacity in a wide ambient-temperature
range (250~400K). However, unfortunately there exist
few candidates. For example, although the damping capacity
of the relaxation-type peak in Ti-Ni-based martensitic
alloys can be as high as 0.04~0.2, it locates at too
low a temperature (200~260K) to be useful for ambient-temperature
applications.
In the present study, by selecting a martensitic alloy
Ti-45Pd-5Cr, which exhibits a high martensitic transformation
temperature (Ms~520K), Zhou et al. succeeded in shifting
the relaxation-type high damping peak to the useful
ambient-temperature range. In the hydrogen-doped martensitic
state, there exists a relaxation-type high damping peak
(Q-1~0.09) extending over 305~370K. Such a relaxation
peak disappears after de-hydrogenation; such contrasting
behavior suggests that this relaxation peak is due to
the twin boundaries and hydrogen interaction. Furthermore,
in the hydrogen-free martensitic state, there is a fascinating
high damping plateau (Q-1~0.05) covering the whole ambient-temperature
range (250~450K). Our work sheds new light into how
to develop high damping alloys for desired temperature
range.
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