Study of the Incommensurate Phase in NiTi(Fe) Alloys

The incommensurate phase and the “locked-in” R phase in NiTi(Fe) alloys are studied by low frequency internal friction, TEM studies in situ, electric resistance measurement, DSC, and tensile tests. A small shoulder-like internal friction peak P1 is found on cooling and heating slightly below the N–I transition temperature. At the same temperature range as P1, mottled microdomains are observed in TEM study by superlattice dark-field images. The internal friction peak P1 is attributed to the stress induced motiion of the mottled microdomain boundaries. On further cooling the internal friction peak P2 appears before the high peak of R phase transition. At P2 temperature range, anti-phase like domains are found in TEM studies. Internal friction properties and DSC measurements suggest that the N–I transition in NiTi(Fe) alloys is of second order. Mittels innerer Reibung bei niedrigen Frequenzen, TEM in-situ, Messungen des elektrischen Widerstands, DSC- und Dehnungs-Test werden die inkommensurable Phase und die „locked-in”-R-Phase in NiTi(Fe)-Legierungen untersucht. Ein kleines schulterformiges Maximum der inneren Reibung, P1, wird bei Abkuhlung und Aufheizung knapp unterhalb der N–I-Ubergangstemperatur gefunden. Im gleichen Temperaturbereich wie P1, werden eingesprengte Mikrodomanen im TEM durch Supergitterdunkelfeld-Diagramme beobachtet. Das Maximum der inneren Reibung, P1, wird der spannungsinduzierten Bewegung der Grenzen der eingesprengten Mikrodomanen zugeordnet. Bei weiterer Abkuhlung tritt ein Maximum der inneren Reibung, P2, vor dem hohen Maximum des R-Phasenubergangs auf. Im P2-Temperaturbereich werden antiphasenahnliche Domanen in den TEM-Untersuchungen gefunden. Die Eigenschaften der inneren Reibung und die DSC-Messungen zeigen, das der N–I-Ubergang in NiTi(Fe)-Legierungen von zweiter Ordnung ist.

[1]  chen xiaohua,et al.  Internal Friction Associated with the Domain Walls and the Second‐Order Ferroelastic Transition in LNPP , 1987 .

[2]  Salamon,et al.  Premartensitic phases of Ti50Ni47Fe3. , 1985, Physical review. B, Condensed matter.

[3]  J. Allain,et al.  Observation of a soft-phonon mode and a pre-martensitic phase in the intermetallic compound Ti50Ni47Fe3 studied by inelastic neutron scattering , 1984 .

[4]  Y. Fujii,et al.  X-ray investigation of the premartensitic phase in Ni 46.8 Ti 50 Fe 3.2 , 1984 .

[5]  C. M. Wayman,et al.  Phonon softening in Ni46.8Ti50Fe3.2 , 1984 .

[6]  C. M. Wayman,et al.  Transformation behaviour of a Ti50Ni47Fe3 alloy I. Premartensitic phenomena and the incommensurate phase , 1983 .

[7]  R. Fleming,et al.  Microstructure in the incommensurate and the commensurate charge-density-wave states of 2 H -Ta Se 2 : A direct observation by electron microscopy , 1982 .

[8]  K. Fung,et al.  Broken hexagonal symmetry in the locked-in state of 2Ha-TaSe2 and the discommensurate microstructure of its incommensurate CDW states , 1981 .

[9]  O. Mercier,et al.  Low-frequency internal friction peaks associated with the martensitic phase transformation of NiTi , 1979 .

[10]  W. L. Mcmillan.  Theory of discommensurations and the commensurate-incommensurate charge-density-wave phase transition , 1976 .

[11]  F. D. Salvo,et al.  Elasticity measurements in the layered dichalcogenides TaSe/sub 2/ and NbSe/sub 2/ , 1975 .

[12]  A. J. Perkins,et al.  The premartensitic instability in near-equiatomic TiNi , 1971 .

[13]  K. Shimizu,et al.  Crystal structure and internal defects of equiatomic TiNi martensite , 1971 .

[14]  R. Hasiguti,et al.  Internal Friction and Related Properties of the TiNi Intermetallic Compound , 1968 .

[15]  G. Purdy,et al.  Calorimetric Study of a Diffusionless Phase Transition in TiNi , 1966 .

[16]  D. Bradley.  Sound Propagation in Near‐Stoichiometric Ti‐Ni Alloys , 1965 .