Precursor effects and premartensitic transformation in Ni{sub 2}MnGa
- Brookhaven National Laboratory, Upton, New York 11973 (United States)
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Inelastic neutron scattering and neutron diffraction were used to study a single crystal of the Ni{sub 2}MnGa shape memory Heusler alloy in a wide temperature range covering the parent phase ({ital T}{gt}{ital T}{sub 1}=260 K), a premartensitic phase ({ital T}{sub 1}{gt}{ital T}{gt}{ital T}{sub {ital M}}), and a martensitic ({ital T}{lt}{ital T}{sub {ital M}}=220 K) phase region. Several anomalies in the phonon dispersion curves in the parent phase were observed. The premartensitic phase involves a transverse modulation of the parent cubic structure with a simple periodicity of (1/3,1/3,0). The approximately tetragonal lattice of the low-temperature martensite is distorted by transverse modulations with incommensurate wave vectors ({zeta}{sub {ital M}},{zeta}{sub {ital M}},0), {zeta}{sub {ital M}}{approx_equal}0.43. The observed phenomena are attributed to electron-phonon interactions and anharmonic effects. {copyright} {ital 1996 The American Physical Society.}
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016; W-7405-ENG-48
- OSTI ID:
- 401144
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 21; Other Information: PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HEUSLER ALLOYS
METALLURGICAL EFFECTS
NICKEL ALLOYS
MANGANESE ALLOYS
GALLIUM ALLOYS
TERNARY ALLOY SYSTEMS
MONOCRYSTALS
SHAPE MEMORY EFFECT
ELECTRON-PHONON COUPLING
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
NEUTRON DIFFRACTION
MARTENSITIC TRANSITIONS