Physical metallurgy of Ti–Ni-based shape memory alloys

1 Introduction.- 1. History.- 2. Scope of Present Book and Review of Past Books.- 3. Name-Calling.- 4. Areas Related to Electron Spectroscopy Not to be Discussed in Detail.- 4.1. Electron-Impact Spectroscopy.- 4.2. Photoemission.- 4.3. Penning Ionization Spectroscopy.- 4.4. Ion Neutralization Spectroscopy.- 5. Fields Related to Electron Spectroscopy.- 2 Instrumentation and Experimental Procedures.- 1. Source Volume.- 1.1. Excitation Devices.- 1.1.1. Electron Gun.- 1.1.2. X-Ray Tube.- 1.1.3. Synchrotron Radiation.- 1.1.4. Vacuum-UV Sources.- 1.2. Target Sample.- 1.2.1. Gases.- 1.2.2. Solids.- 1.2.3. Condensed Vapors, Liquids, and Targets at Other Than Room Temperature.- 1.3. Chamber for Angular Distribution Studies.- 1.4. Preacceleration and Deceleration.- 2. Analyzer.- 2.1. Cancellation of Magnetic Fields.- 2.1.1. Helmholtz Coils.- 2.1.2. Magnetic Shielding.- 2.2. Types of Analyzers.- 2.2.1. Retarding Grid.- 2.2.2. Dispersion.- 3. Detector Systems and Data Analysis.- 3.1. Single-Channel Detector.- 3.2. Position-Sensitive Detector.- 3.3. Scanning the Spectrum.- 3.4. Data Analysis.- 4. New Developments.- 5. Review of Commercial Instruments.- 5.1. AEI.- 5.2. Du Pont.- 5.3. Hewlett-Packard.- 5.4. McPherson.- 5.5. Perkin-Elmer.- 5.6. Physical Electronics.- 5.7. McCrone-RCI.- 5.8. Vacuum Generators, Inc..- 5.9. Varian.- 5.10. Others.- 3 Fundamental Concepts.- 1. Photoelectric Effect.- 2. Binding Energy.- 3. Final States and the Sudden Approximation.- 3.1. Spin-Orbit Splitting.- 3.2. Multiplet Splitting.- 3.3. Jahn-Teller Splitting.- 3.4. Electron Shakeoff and Shakeup.- 3.5. Configuration Interaction.- 3.6. Koopmans' Theorem and the Sudden Approximation.- 3.7. Vibrational and Rotational Final States.- 4. Atomic Wave Functions.- 5. Molecular Orbital Theory.- 5.1. Theoretical Models.- 5.1.1. Ab Initio Calculations.- 5.1.2. Semiempirical Calculations.- 5.2. Basis Set Extension and MO Mixing.- 5.3. Atomic and Molecular Orbital Nomenclature.- 5.3.1. Atoms.- 5.3.2. Molecules.- 4 Photoelectron Spectroscopy of the Outer Shells.- 1. Introduction.- 2. Energy Level Scheme.- 2.1. Binding Energy.- 2.2. Final States.- 2.2.1. Spin-Orbit Splitting.- 2.2.2. Multiplet Splitting due to Spin Coupling.- 2.2.3. Jahn-Teller Effect.- 2.2.4. Electron Shakeoff and Shakeup.- 2.2.5. Configuration Interaction.- 2.2.6. Resonance Absorption.- 2.2.7. Collision Peaks.- 3. Identification of the Orbital.- 3.1. Ionization Potentials.- 3.1.1. Characteristic Ionization Bands.- 3.1.2. Effects of Substituents.- 3.1.3. Sum Rule.- 3.1.4. The Perfluoro Effect.- 3.1.5. Dependence on Steric Effects.- 3.2. Identification of Orbitals by Vibrational Structure.- 3.3. Identification of Molecular Orbitals from Intensities of Ionization Bands.- 3.4. Identification of Molecular Orbitals by Angular Distribution.- 4. Comparison of PESOS with Other Experimental Data.- 4.1. Optical Spectroscopy.- 4.2. Mass Spectroscopy.- 5. Survey of the Literature on PESOS.- 5.1. Atoms.- 5.2. Diatomic Molecules.- 5.2.1. H2.- 5.2.2. N2 and CO.- 5.2.3. O2 and NO.- 5.2.4. Diatomic Molecules Containing Halogen.- 5.3. Triatomic Molecules.- 5.3.1. Linear Triatomic Molecules.- 5.3.2. Bent Triatomic Molecules.- 5.4. Organic Molecules.- 5.4.1. Methane, Alkanes, and Tetrahedral Symmetry.- 5.4.2. Unsaturated Aliphatics.- 5.4.3. Ring Compounds.- 5.4.4. Multiring Compounds.- 5.4.5. Organic Halides.- 5.4.6. Miscellaneous Organic Compounds Containing Oxygen, Nitrogen, Sulfur, and Phosphorus.- 5.5. Organometallics and Miscellaneous Inorganic Polyatomic Molecules.- 5.6. Ions, Transient Species, and Other Special Studies in PESOS.- 6. Studies on Solids.- 7. Analytical Applications of PESOS.- 5 Photoelectron Spectroscopy of the Inner Shells.- 1. Atomic Structure.- 2. Theoretical Basis of Chemical Shifts of Core Electrons.- 2.1. Valence Shell Potential Model.- 2.2. Effect of Neighboring Atoms.- 2.3. Calculation of Net Charge from Electronegativity.- 2.4. Calculation of Net Charge from Semiempirical MO.- 2.5. Use of Ab Initio Calculations for Chemical Shifts.- 2.6. Correlation of Chemical Shift with Thermochemical Data.- 3. Summary of Data on Chemical Shifts as a Function of the Periodic Table.- 3.1. Carbon.- 3.2. Nitrogen and Phosphorus.- 3.3. Sulfur and Oxygen.- 3.4. Group IIIA, IVA, VA, and VIA Elements.- 3.4.1. Group IIIA: B, Al, Ga, In, and Tl.- 3.4.2. Group IVA: C, Si, Ge, Sn, and Pb.- 3.4.3. Group VA: N, P, As, Sb, and Bi.- 3.4.4. Group VIA: O, S, Se, and Te.- 3.5. Halides and Rare Gases.- 3.6. Alkali Metals and Alkaline Earths.- 3.7. Transition Metals.- 3.7.1. First Transition Metal Series: Sc, Ti, V, Cr, Mn, Fe, Co, Ni.- 3.7.2. Second Transition Metal Series: Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd.- 3.7.3. Third Transition Metal Series: Hf, Ta, W, Re, Os, Ir, Pt.- 3.8. Groups IB and IIB: Cu, Ag, Au, Zn, Cd, Hg.- 3.9. Rare Earths and Actinides.- 4. Special Topics on Shifts in Core Binding Energies.- 4.1. Experimental and Interpretive Problems in PESIS.- 4.1.1. Comparative Problems in the Gas and Solid Phases.- 4.1.2. Charging.- 4.1.3. Definition of Binding Energy for Insulators.- 4.1.4. Binding Energy of Surface Atoms.- 4.1.5. Radiation Effects.- 4.1.6. Linewidths.- 4.2. Inorganic Compounds.- 4.2.1. Multiple Chemical Environment.- 4.2.2. Coordination Complexes.- 4.3. Organic Compounds.- 4.3.1. Resonance.- 4.3.2. Substituent Effects.- 4.3.3. Group Analysis.- 4.3.4. Specific Studies on Organic Molecules.- 4.4. Comparison of Core Electron Binding Energy Shifts with Other Physical Quantities.- 4.4.1. Mossbauer Isomer Shift.- 4.4.2. NMR.- 4.4.3. Other Physical Data.- 5. Other Applications of PESIS.- 5.1. Multicomponent Structure.- 5.1.1. Multiplet or Exchange Splitting.- 5.1.2. Electron Shakeoff and Shakeup.- 5.1.3. Configuration Interaction.- 5.1.4. Characteristic Energy Losses.- 5.1.5. Determining the Nature of Multicomponent Structure.- 5.2. PESIS for Surface Studies.- 5.3. Angular Studies with PESIS.- 6. Use of PESIS for Applied Research.- 6.1. PESIS as an Analytical Tool.- 6.2. Biological Systems.- 6.3. Geology.- 6.4. Environmental Studies.- 6.5. Surface Studies.- 6.6. Polymers and Alloys.- 6.7. Radiation Studies.- 6.8. Industrial Uses.- 6 Auger Electron Spectroscopy.- 1. Theory of the Auger Process.- 2. Comparison of the Auger Phenomenon with the Photoelectric Effect and X-Ray Emission.- 3. Use of Auger Spectroscopy for Gases.- 3.1. Atoms.- 3.2. Molecules.- 3.3. Study of Ionization Phenomena by Auger Spectroscopy.- 3.4. Autoionization.- 3.5. Auger Spectroscopy for Use in Gas Analysis.- 4. Use of Auger Spectroscopy in the Study of Solids.- 4.1. Special Problems Encountered on Using AES with Solids.- 4.1.1. Variables Concerned with Production of Auger Electrons.- 4.1.2. High-Energy Satellite Lines.- 4.1.3. Characteristic Energy Losses.- 4.1.4. Charging in Nonconducting Samples.- 4.2. High-Resolution Auger Spectroscopy with Solids.- 4.3. General Analytical Use of Auger Spectroscopy.- 4.4. Use of Auger Spectroscopy in the Study of Surfaces.- 4.4.1. General Considerations.- 4.4.2. Literature Survey of Surface Applications.- 4.5. Other Methods for Surface Analysis.- 4.5.1. Comparison of PESIS and Auger Spectroscopy for Surface Studies.- 4.5.2. Methods of Surface Analysis Other than AES and PESIS.- Appendixes.- 1. Atomic Binding Energies for Each Subshell for Elements Z = 1-106.- 3. Compilation of Data on Shifts in Core Binding Energies.- 4. Acronyms and Definitions of Special Interest in Electron Spectroscopy.- References.

Photoelectron and Auger Spectroscopy

The deformation behaviour of intermetallic superlattice compounds

A MICROMECHANICS constitutive model has been proposed in this paper to describe the pseudoelastic and shape memory behavior of polycrystalline shape memory alloys under various temperatures The derivation of the model is based on the thermodynamics, micromechanics and microstructural physical mechanism analysis of the material during deformation and it is shown that the inelastic deformation of the material in the mechanical and/or thermal loading processes is associated with some temperature, stress state and loading history dependent yielding surfaces which microscopically correspond to the forward and reverse transformation (or reorientation) processes, respectively

Micromechanics modelling for the constitutive behavior of polycrystalline shape memory alloys. I: Derivation of general relations

Etude de l'influence de la teneur en cuivre (5, 7.5, 10, 12.5, 15, 20at%) sur les caracteristiques de memoire de forme (temperatures de transformation, allongement, hysteresis) des alliages Ti 50 Ni 50-x Cu x .

Cu-Content Dependence of Shape Memory Characteristics in Ti–Ni–Cu Alloys

Thermoelastic martensitic transformation has been studied by the analysis of stress-strain curves in binary Au-Cd alloys, containing 46·5, 47·5, 48·5, 49, 49·5, and 50 at. % Cd, respectively. The pseudoelastic characteristics, i.e. superelastic and ferroelastic behaviour upon tension compression test and that the origin of the shape memory effect bears a close relation to the ferroelastic loop, have been explained on the basis of the lattice softening, that is. the shear elastic constant, C′ = (C11-C12)/2, decreases toward zero in the vicinity of the transition temperature. In particular the critical condition for obtaining the ferroelastic loop can be experimentally determined by assuming a critical stress, which is termed ‘ferroelastic limit’. The ferroelastic limit may depend upon the elastic anisotropy of alloys and lies in the region 6 Kg/mm- in the Au-Cd alloy.

Pseudoelasticity in Au-Cd thermoelastic martensite

Pseudoelasticity and elastic anisotropy in the β phase thermoelastic alloys

Superlattice formation in the ternary β phase alloys—II. Application of the statistical thermodynamics

Relationships between displacive phase transitions and soft modes are discussed and illustrated using experimental examples. Ferroelectric and ferroelastic transitions are dealed with together with the \"band-Jahn-Teller\" and antiferromagnetic transitions which are closely connected with acoustic soft modes. Since an acoustic mode softening has been observed in the vicinity of the martensitic transformation temperatures in R-phase alloys, it is of importance to discuss the close relation between the nucleation mechanism of martensite and the crystal anharmonicity near the M temperature. ( I ) Displacive Phase Transitions and Soft Modes in Non-metallic Materials. (1) Condensation of r15(0ptical) Mode at the Center of the Brillouin Zone (BaTi03) The concept of \"soft phonon\" associated with a phase transition signifies a phenomenon in which a phonon mode, which coincides with a lower-symmetry structure, is very much amplified immediately before the onset of phase transition from a higher-symmetry structure. Fig. l(a) shows a unit cell of perovskite structure (ABX3) in which the A ions occupy the corners of a cube, X ions the face centres of this cubic and thus forming and octahedron and the B ions the body centre of the cube and the octahedron. Lattice vibrations in this unit cell can be described by the mutual vibrations among these three sublattices and by the displacement modes of the octahedron (X6). The Brillouin zone is a simple cubic lattice as shown in Fig. l(b). Soft modes which have been found so far are the r15, M3 and R25 having their wave numbers at the r point (zone center), at the M point (1/2, 1/2, O)a* and at the R point (1/2, 1/2, 1/2)a* (zone boundaries), respectively. BaTi03, having a perovskite structure, is a typical crystal which exhibits successive phase transitions with the soft modes playing an important role in the transitions. BaTi03 is paraelectric at high temperatures and the following displacive phase transitions occur successively upon cooling; (1) as the temperature approaches 393 K, the ions begin to be displaced, which results in a spontaneous polarization along the [001] direction, (2) upon further cooling to 278 K, the polarization vector changes its direction to [011] and (3) finally at the lowest transition temperature, 193 K, the polarization vector changes to the [ill] direction. It is characteristic, however, that very slight distortions from the basic perovskite structure are associated with these transitions. In terms of condensed soft modes these phase transitions can be understood as follows; the frequency, wTO , of r15 mode (q = 0), which degenerates triply in the cubic lattice, decreases toward zero when the temperature approaches the transition point. Consequently, the restoring force is reduced resulting in the condensation of the ionic displacements corresponding to the r15 mode, thus leading to tha lower-symmetric static structure. Since the tetragonal crystal can be formed by the r mode having the [001] displacement, the temperature change in the frequency, wTo(bY, is given as ~ ~ ~ ~ ( 0 ) = A (T To , (1) Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1982403 C4-36 JOURNAL DE PHYSIQUE where To represents the second order phase transition temperature. The first-order transition in BaTiO3takes place at 393 K which is higher than To. 0 A(O.O.0) B ( + . + . + , 0 x (J. i .o),(+.o.+),(o.~.+ ) T Kz Fig. 1 (a) Pervoskite structure and (b) its Brillouin zone. When the tetragonal lattice is formed at 393 K, the triply degenerated r15 mode is resolved into one mode which is parallel to the C axis, and into other modes of doubly degenerated components which are normal to the C axis direction in the tetragonal lattice. The latter components become soft again and one of them condenses at 278 K, inducing a transformation into an orthorhombic crystal, where the polarization changes its direction to [011] because the [010] direction of ionic displacement was coupled with that of already condensed Tool] mode. Finally, the retained r15 mode with its [loo] displacement vector softens and condenses at 193 K, with the crystal structure consequently being changed into trigonal with [ill] polarization. It has been proposed and is well known that the Lyddane-Sache-Teller relation (1) exists between the frequencies of optical modes with q = 0, ui0(0) and wi0(0), and the dielectric constant, E (0) : Here, E ( m ) represents the optical part of the dielectric constant which is not dependent on temperature. If a soft mode exists and that the temperature variation of its frequency follows eq. (1) the dielectric constant ~ (0) should then obey the Curie-Weiss's law. Anomalies in the changes in specific heat and entropy observed at the transition temperature can be explained by the soft modes. (2) Acoustic Soft Mode due to Piezoelectric Coupling (KH2P04) KDP and its isomorphs represent an important class of hydrogen-bonded ferroelectrics (3). Brody-Cummins (2) have observed an acoustic soft mode in KH2P04 (KDP) by means of Brillouin scattering technique. The KDP crystal belongs to the space group 142d(D;$) in the paraelectric phase and transforms to a ferroelectric phase F'dd2(~;') when the transition temperature is attained. As shown in Figs. 2(a) and (b) , four K-PO4 groups are contained in the unit cell, and each PO4 group is connected to four neighbouring PO4 groups by 0--H-0 bonds lying in the basal plane. Although the protons are thought to play an important role in the transition mechanism, the spontaneous polarization in the ferroelectric phase is parallel to the C-axis and essentially perpendicular to the proton motion. Thus the ferroelectric properties cannot be accounted for by the proton motion alone (see Fig. 2(b)). Therefore, the transition mechanism in these materials is that when the protons order, their motion being strongly coupled with an optic mode of the lattice, the proton-lattice interaction may cause a subsequent distortion of the K-PO4 sublattices producing the spontaneous polarization. Among theoretical treatments of the phase transition, Kobayashi (4) has considered the coupling between the proton motion and an optic mode of the lattice. The treatment resulted in a transition involving a long-wavelength (q = 0) mode of the coupled system, and ordering of the of the protons on the 0--H-0 bonds. In the parelectric phase, the free energy of the piezoelectric crystal is, in general, described as (5) x -1 2 F = 1/2(x ) P + aPx + 1/2CPx2 ( 3 ) where ( Xx)-l is the clamped inverse susceptibility, a the piezoelectric coefficient and CP the elastic stiffness at constant polarization. As is well-known, the free inverse susceptibility (XX) and the elastic stiffness at constant electric field cE are, respectively, given by E (xX)-l = (xX)-l a2/cP; c = cP-a2/(XX)-l (4),(5) In KDP, since the transition is well described by the free energy 2 P 2 F = 1/2a(T-To)P + aPx + l/2C x (6) x -1the following relations are experimentally confirmed : (X ) -a(T-To); C =constant (7),(8) That the primary order parameter is indeed the polarization is clearly shown from the Landau theory. From eqs. (4) and (5), T-T 2 (xX)-I = a(T-To) C E = C P ~ = C P ~ 6 T-TO a(T-To) (9)9(10)

Lattice stability and soft modes

Superelastic behaviour in Au-47·5 at.% Cd and Au-49·5 at.% Cd was studied using microscopic surface observation, an analysis of Laue photographs and measurement of the strain distribution. The superelasticity above the transformation temperature, T0, in Au—47·5 at. % Cd alloy was associated with the transformation, β(b.c.c.) β'(orthorhombic) upon loading and β'-β upon unloading. Below T0, superelasticity in a quenched and aged martensite was due to migration of twin boundaries in the martensite crystal. In Au—49-5 at.% Cd alloy, below T0, a significant superelasticity was observed when the specimen axis was near the [100]β pole. This superelasticity was accompanied by the transformation β“(hexagonal) β’ upon loading and β→β” upon unloading. Above T0, the superelasticity observed was identical to that found in Au-47-5 at.% Cd. In the stress-induced transformation, upon loading, a band consisting of alternate layers of the b.c.e. phase and the martensite phase was formed at one end of the specimen ...

Y. Murakami

Papers

Pseudoelasticity in Au-Cd thermoelastic martensite

Pseudoelasticity and elastic anisotropy in the β phase thermoelastic alloys

Superlattice formation in the ternary β phase alloys—II. Application of the statistical thermodynamics

Lattice stability and soft modes

Study of superelasticity associated with the thermoelastic martensitic transformation in Au—Cd alloys