Direct observation of the alpha-epsilon transition in shock-compressed iron via nanosecond x-ray diffraction.
In situ x-ray diffraction studies of iron under shock conditions confirm unambiguously a phase change from the bcc (alpha) to hcp (epsilon) structure. Previous identification of this transition in shock-loaded iron has been inferred from the correlation between shock-wave-profile analyses and static high-pressure x-ray measurements. This correlation is intrinsically limited because dynamic loading can markedly affect the structural modifications of solids. The in situ measurements are consistent with a uniaxial collapse along the [001] direction and shuffling of alternate (110) planes of atoms, and are in good agreement with large-scale nonequilibrium molecular dynamics simulations.
Kalantar
D H
DH
Lawrence Livermore National Laboratory, California 94550, USA.
Belak
J F
JF
Collins
G W
GW
Colvin
J D
JD
Davies
H M
HM
Eggert
J H
JH
Germann
T C
TC
Hawreliak
J
J
Holian
B L
BL
Kadau
K
K
Lomdahl
P S
PS
Lorenzana
H E
HE
Meyers
M A
MA
Rosolankova
K
K
Schneider
M S
MS
Sheppard
J
J
Stölken
J S
JS
Wark
J S
JS