TY - JOUR

T1 - Change of regime of decay of elastic precursor wave in BCC metals

AU - Zaretsky, Eugene

AU - Kanel, Gennady

PY - 2015/6/1

Y1 - 2015/6/1

N2 - Our studies of decay of elastic precursor wave with propagation distance
in five BCC metals, namely V, Ta, Fe, Nb, and Mo show that at
propagation distances of about h * = 1 mm the regime of the decay is
changed. At propagation distances smaller than h * the decay is fast and
the spatial variation of the elastic wave amplitude
σHEL is described by the power function
σHEL =σ0(h
/h0)-α with α ranged between 0.3 and
0.7 for different metals at different temperatures. Beyond the distance
h * the decay is much slower and is characterized by much lower values
of α, of about 0.1 or less. The stresses τ* at which the
transition occurs at room temperature is close to the Peierls stresses
τP of the studied metals. This allows us to conclude that
the change of the decay regime at τ* is caused by the change of the
mode of the dislocations motion from the over-barrier glide controlled
by the phonon viscous drag above τ* to that controlled by thermally
activated generation/motion of the dislocation double-kinks below
τ*. The decline of τ* with temperature (~ 50% over 1000-K
interval) agrees with the growing with temperature support of
dislocation motion by thermal fluctuation.

AB - Our studies of decay of elastic precursor wave with propagation distance
in five BCC metals, namely V, Ta, Fe, Nb, and Mo show that at
propagation distances of about h * = 1 mm the regime of the decay is
changed. At propagation distances smaller than h * the decay is fast and
the spatial variation of the elastic wave amplitude
σHEL is described by the power function
σHEL =σ0(h
/h0)-α with α ranged between 0.3 and
0.7 for different metals at different temperatures. Beyond the distance
h * the decay is much slower and is characterized by much lower values
of α, of about 0.1 or less. The stresses τ* at which the
transition occurs at room temperature is close to the Peierls stresses
τP of the studied metals. This allows us to conclude that
the change of the decay regime at τ* is caused by the change of the
mode of the dislocations motion from the over-barrier glide controlled
by the phonon viscous drag above τ* to that controlled by thermally
activated generation/motion of the dislocation double-kinks below
τ*. The decline of τ* with temperature (~ 50% over 1000-K
interval) agrees with the growing with temperature support of
dislocation motion by thermal fluctuation.

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JO - APS Topical Conference on the Shock Compression of Matter 2015

JF - APS Topical Conference on the Shock Compression of Matter 2015

ER -