TY - JOUR
T1 - Shock-induced twinning in polycrystalline vanadium
T2 - II. Surface layer
AU - Hazan, A.
AU - Hillel, G.
AU - Kalabukhov, S.
AU - Frage, N.
AU - Zaretsky, E. B.
AU - Meshi, L.
N1 - Funding Information:
Dr. V. Ezersky's help with HRTEM and EELS is greatly acknowledged. Financial supports of the Israel Science Foundation (grant 441/18 ) to E.B. Zaretsky and N. Frage, and the Israeli Ministry of Defense (grant 8757643 ) to E.B. Zaretsky are gratefully acknowledged.
Publisher Copyright:
© 2021 Elsevier Inc.
PY - 2021/5/1
Y1 - 2021/5/1
N2 - In the course of study of shock-induced twinning in commercially pure (99.8 wt%) polycrystalline vanadium, some unexpected metallurgical features were found. In all vanadium samples softly recovered after planar impact loading by copper impactors with velocities ranging from 262 to 610 m/s, the domain of twinned grains (located at the distance 100–900 μm from an impacted sample surface) preceded by a relatively narrow strip, 60–100 μm, densely filled by martensite lenticles of micron size. The distribution of shock-induced twins and the stress, required for their nucleation, were considered in the Part I of the present paper series. Part II of this series is focused on the Transmission Electron Microscopy study of the lenticles, formed in immediate proximity to the impacted surface. It was found that these lenticular particles are oblate ellipsoids of micron size filled with the stacks of 10–30 nm thick planar slabs, which possess tetragonal crystal structure. The slabs have alternating orientation of tetragonal axes c while the parameters of their unit cell are derivatives of cubic lattice parameter of vanadium, aV, namely a = b = 2aV and c = aV. Possible model, based on a sequence of glides, capable to generate such microstructure, and the cause for the disappearance of the lenticles beyond 100 μm apart from the impacted surface are discussed.
AB - In the course of study of shock-induced twinning in commercially pure (99.8 wt%) polycrystalline vanadium, some unexpected metallurgical features were found. In all vanadium samples softly recovered after planar impact loading by copper impactors with velocities ranging from 262 to 610 m/s, the domain of twinned grains (located at the distance 100–900 μm from an impacted sample surface) preceded by a relatively narrow strip, 60–100 μm, densely filled by martensite lenticles of micron size. The distribution of shock-induced twins and the stress, required for their nucleation, were considered in the Part I of the present paper series. Part II of this series is focused on the Transmission Electron Microscopy study of the lenticles, formed in immediate proximity to the impacted surface. It was found that these lenticular particles are oblate ellipsoids of micron size filled with the stacks of 10–30 nm thick planar slabs, which possess tetragonal crystal structure. The slabs have alternating orientation of tetragonal axes c while the parameters of their unit cell are derivatives of cubic lattice parameter of vanadium, aV, namely a = b = 2aV and c = aV. Possible model, based on a sequence of glides, capable to generate such microstructure, and the cause for the disappearance of the lenticles beyond 100 μm apart from the impacted surface are discussed.
KW - Impact loading
KW - Plastic deformation
KW - Structure characterization
KW - TEM
KW - Twins
KW - Vanadium
UR - http://www.scopus.com/inward/record.url?scp=85103404494&partnerID=8YFLogxK
U2 - 10.1016/j.matchar.2021.111062
DO - 10.1016/j.matchar.2021.111062
M3 - Article
AN - SCOPUS:85103404494
SN - 1044-5803
VL - 175
JO - Materials Characterization
JF - Materials Characterization
M1 - 111062
ER -