Shock-induced martensitic transformations in near-equiatomic NiTi alloys
- Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering
- Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering
- Los Alamos National Lab, NM (United States). Center for Materials Science
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.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States); USDOE, Washington, DC (United States)
- OSTI ID:
- 522358
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 28, Issue 7; Other Information: PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
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