

Preprint 87/2008
Energy barriers and hysteresis in martensitic phase transformations
Zhiyong Zhang, Richard D. James, and Stefan Müller
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Submission date: 04. Dec. 2008
Pages: 41
published in: Acta materialia, 57 (2009) 15, p. 4332-4352
DOI number (of the published article): 10.1016/j.actamat.2009.05.034
Bibtex
Keywords and phrases: Martensitic phase transformation, hysteresis, nucleation and growth, nickel-titanium alloys, continuum mechanics
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Abstract:
We report results from a systematic program of alloy development
in the system TiNiX, X = Cu, Pt, Pd, Au, to
pursue certain special lattice
parameters that have been identified previously with low hysteresis.
We achieve , where
is the middle eigenvalue
of the transformation strain matrix, for alloys with X = Pt, Pd, Au.
In all cases there is a sharp drop of the graph of hysteresis
vs. composition at the composition where
. When the
size of the hysteresis is replotted vs.
we obtain a
universal graph for these alloys.
Motivated by these experimental
results, we present a new theory for the size of the hysteresis based
on the growth from a small scale of fully developed austenite
martensite needles. The energy of the transition layer
plays a critical role in this theory. Overall, the results
point to a simple systematic method of achieving
low hysteresis and a high degree of reversibility in transforming
materials.