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Title: Shock-induced martensitic transformations in near-equiatomic NiTi alloys

Abstract

Shock-impact generated tensile-stress pulses were used to induce B2-to-monoclinic martensitic transformations in two near-equiatomic NiTi alloys having different martensite transformation start (M{sub s}) temperatures. The NiTi-I alloy (M{sub s} {approx} +27 C) impacted at room temperature at 2.0 and 2.7 GPa tensile stress-pulse magnitude, showed acicular martensite morphology. These martensite needles had a substructure containing microtwins, typical of stress-assisted martensite. The NiTi-II alloy (M{sub s} {approx} {minus}45 C) showed no martensite formation when shocked with tensile-stress pulses of 2 GPa. For tensile stresses of 4.1 GPa, the alloy showed spall initiation near the region of maximum tensile-stress duration. In addition, monoclinic martensite needles, with a well-defined dislocation substructure, typical of strain-induced martensite, were seen clustering around the spall region. No stress-assisted martensite was formed in this alloy due to its very low M{sub s} temperature. The present article documents results of the use of a metallurgical technique for generating large-amplitude tensile stress pulses of finite duration for studies of phase transformations involving changes from a high density to a low density state.

Authors:
 [1];  [2];  [3]
  1. Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering
  2. Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering
  3. Los Alamos National Lab, NM (United States). Center for Materials Science
Publication Date:
Sponsoring Org.:
National Science Foundation, Washington, DC (United States); USDOE, Washington, DC (United States)
OSTI Identifier:
522358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science; Journal Volume: 28; Journal Issue: 7; Other Information: PBD: Jul 1997
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL-PHASE TRANSFORMATIONS; NICKEL ALLOYS; TITANIUM ALLOYS; MARTENSITE; SHOCK WAVES; MONOCLINIC LATTICES; MORPHOLOGY; STRESSES; DISLOCATIONS

Citation Formats

Thakur, A.M., Thadhani, N.N., and Schwarz, R.B.. Shock-induced martensitic transformations in near-equiatomic NiTi alloys. United States: N. p., 1997. Web. doi:10.1007/s11661-997-0207-2.
Thakur, A.M., Thadhani, N.N., & Schwarz, R.B.. Shock-induced martensitic transformations in near-equiatomic NiTi alloys. United States. doi:10.1007/s11661-997-0207-2.
Thakur, A.M., Thadhani, N.N., and Schwarz, R.B.. Tue . "Shock-induced martensitic transformations in near-equiatomic NiTi alloys". United States. doi:10.1007/s11661-997-0207-2.
@article{osti_522358,
title = {Shock-induced martensitic transformations in near-equiatomic NiTi alloys},
author = {Thakur, A.M. and Thadhani, N.N. and Schwarz, R.B.},
abstractNote = {Shock-impact generated tensile-stress pulses were used to induce B2-to-monoclinic martensitic transformations in two near-equiatomic NiTi alloys having different martensite transformation start (M{sub s}) temperatures. The NiTi-I alloy (M{sub s} {approx} +27 C) impacted at room temperature at 2.0 and 2.7 GPa tensile stress-pulse magnitude, showed acicular martensite morphology. These martensite needles had a substructure containing microtwins, typical of stress-assisted martensite. The NiTi-II alloy (M{sub s} {approx} {minus}45 C) showed no martensite formation when shocked with tensile-stress pulses of 2 GPa. For tensile stresses of 4.1 GPa, the alloy showed spall initiation near the region of maximum tensile-stress duration. In addition, monoclinic martensite needles, with a well-defined dislocation substructure, typical of strain-induced martensite, were seen clustering around the spall region. No stress-assisted martensite was formed in this alloy due to its very low M{sub s} temperature. The present article documents results of the use of a metallurgical technique for generating large-amplitude tensile stress pulses of finite duration for studies of phase transformations involving changes from a high density to a low density state.},
doi = {10.1007/s11661-997-0207-2},
journal = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science},
number = 7,
volume = 28,
place = {United States},
year = {Tue Jul 01 00:00:00 EDT 1997},
month = {Tue Jul 01 00:00:00 EDT 1997}
}