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Cold-rolling behavior was investigated for B2 intermetallics in terms of chemical compositions (constituent elements and ternary addition), long-range ordering and environments. B2 intermetallics used were NiTi, FeCo and FeAl alloys and cold-rolling behavior was evaluated through Vickers hardness tests at room temperature as a function of reduction of thickness. The effects of compositional deviation from the stoichiometry and Co addition were studied for B2-stabilized NiTi alloys. It was found that reduction to failure is lowered with increasing the compositional deviation from the stoichiometry, i.e. with decreasing Ti content, and Co addition raises both the reduction to failure and hardness. The effects of order–disorder transformation were studied for V-added FeCo alloys, and it was found that the reduction to failure is lowered and the work-hardening rate is raised by ordering. The effects of wet environment and ternary addition were studied for FeAl alloys with or without Mn or Cr. It was found that hardness-reduction relationship slightly depends on environment and ternary addition, and largely depends on Al content. However, formation of cracks and/or burrs is much affected by the environment and the ternary additions in a complex manner. It is summarized for B2 intermetallics that cold-rolling behavior is largely affected by chemical compositions of constituent phases and ordering, and slightly by the environment.

Thermal conductivity of 3Ni–1Al elemental powder compacts was measured using a laser-flash method as a function of temperature, compact density and heat treatment. Temperature dependence of thermal conductivity of the compacts is similar to that of pure Ni and Al metals. Heat treatment has a significant effect on the thermal conductivity of the compacts as particles are joined together to form Ni solid solution and intermetallic phases on powder surfaces. Fast diffusion on powder surfaces during heat treatment results in the formation of intermetallic phase zones in the interior of the former Ni particles.

Ternary addition generally degrades an excellent conduction properties of NiAl. The contour map of thermal conductivity in NiAl–X β single phase field is drawn for the ternary elements X=Ti, Cu and Ge. It is revealed that each element has a characteristic ridge direction in the contour map. This feature is discussed based on the preference substitutional site of a ternary element, and eighteen ternary elements with a sufficient solubility into NiAl are classified into three groups according to the ridge direction. Thermal conductivity of NiAl-based alloys increases with increasing temperature, however the ridge direction in the contour map remains unchanged.

A systematic investigation has been carried out to determine both the γ liquidus and solidus surfaces above the Ni solid solution in the Ni-Al-X ternary phase diagrams successively by differential thermal analysis. Each of the group IV elements in the periodic table, Ti, Zr, and Hf, was chosen as the ternary additive X in the present study. As a basis, γ liquidus and solidus temperatures in the Ni-Al binary system were reinvestigated and evaluated. The γ solvus was also taken into account to determine a temperature range for a solid-solution treatment above the γ solvus, generally called “the window,” as well as the maximum solubility limit of γNi solid solution.

Thermal conductivity of Pt alloys with an fcc single phase was comprehensively surveyed by employing the laser flash method. Thermal conductivity is dominantly determined by alloy composition and temperature and is scarcely influenced by fabrication condition. An addition of solute definitely decreases the thermal conductivity of Pt, and the conductivity-composition relationship is characterized by a sharp maximum at pure Pt. The Wiedemann-Franz relation held for Pt alloys suggests the dominant carrier of thermal conduction is an electron. An empirical rule is proposed that the thermal conductivity decreases significantly as the position of the solute element in the periodic table becomes horizontally more distant from that of Pt. Thermal conductivity of Pt alloys increases with increasing temperature in a range between 300–1100 K, and the temperature coefficient is found to be inversely correlated with the thermal conductivity.

A phase diagram of Ni3V-Co3V pseudobinary system is proposed based on x-ray diffraction and differential thermal analysis. Four invariant reactions are located in the phase diagram—two eutectoid and two peritectoid reactions. Six kinds of geometrically close-packed phases are encountered. The stability of these close-packed phases correlate well with the electron concentration.

Thermal conductivity of an intermetallic compound is characterized as an enhancement due to ordering with reference to the basic contribution of solid solutions. A necessary condition of having high thermal conductivity of a given intermetallic compound is, therefore, that the solid solution itself transports high thermal current. A periodic table in helical form for seeking the high conductivity compound is proposed by summarizing the electrical resistivity data of solid solutions. Assessments of thermal conductivity were conducted for the intermetallic compounds based on noble metals. Cu3Au, CuAu and AgMg show the maximum value for 157, 167 and 147 W m−1 K−1 at ambient temperature among L12, L10 and B2 compounds, respectively.

Effects of ternary additions, Co and Cr, on martensite transformation temperatures and mechanical properties of offstoichiometric NiTi alloys were investigated. Martensite transformation start temperature (M s ) and austenite transformation start temperature (A s ) were determined by means of differential thermal analysis (DTA) in the temperature range between 77 and 423 K. Mechanical properties of yield stress and work-hardening coefficient were investigated using B2-stabilized NiTi alloys, whose alloy compositions were based on Ni-49 mol% Ti. It has been shown that (1) M s and A s considerably decrease with decreasing Ti concentration on the Ti poor side of stoichiometry (the concentration of Ti is less than 50 mol%); (2) M s and A s change slightly when Ti concentration is more than 52 mol%, where the alloys are in the two phase region; and (3) M s and A s decrease with increasing Cr and Co content with a constant Ti concentration. In the present analysis for evaluating the effect of ternary additions on M s , we use M s change by adding 1 mol% of ternary elements. M s changes by Cr addition are −65 K mol% −1 on the Ti rich side and −46 K mol% −1 on the Ti poor side. M s changes by Co addition are −15 K mol% −1 on the Ti rich side and −30 K mol% −1 on the Ti poor side. Both Cr and Co atoms are suggested to locate Ni sites preferably if only M s changes are considered. Characteristic stress-strain curves have indicated that the stress induced martensitic transformation (SIMT) occurred at 77 K. Above room temperature, work hardening coefficient at a permanent strain of 1% was found to be between 2 and 11 GPa. It should be emphasized that yield stress and work hardening coefficient increase with increasing test temperature between room temperature and about 650 K in most alloys. This strength anomaly is not related to SIMT but to precipitation hardening and/or anomalous dislocation motion, probably in a similar manner to B2-type CoTi.

The path probability method of the non-equilibrium statistical mechanism is employed to study the configurational kinetics of the disorder-L12 transition. Spinodal ordering is examined from the standpoint of kinetics. The kinetic path traced in the thermodynamic configurational space deviates from the sleepest descent direction. Assuming a temperature dependent spin flip probability, the calculated aging kinetics exhibit qualitatively the behavior observed in resistivity measurements.

Thermal conductivity of A 3 B intermetallic compounds, where A denotes iron or nickel and B denotes group IIIb or IVb elements, is investigated by a laser-flash method. Among six kinds of L1 2 compounds, the largest thermal conductivity observed is 32 8 Wm −1 K −1 of Ni 3 Ga. In Fe 3 Ga and Fe 3 Ge, three polymorphs, i.e. L1 2 , D0 19 and D0 3 , can be achieved by performing a suitable heat treatment. Thermal conductivity of the D0 19 phase is quite close to that of the L1 2 phase, while the DO, phase shows smaller values. In most A 3 B compounds, the measured thermal conductivities tend to decrease as the position of constituent B becomes horizontally more distant from that of constituent A in the periodic table.

Theoretical investigations on the phase stability of intermetallic compounds are categorized into three groups: studies for the ground-state stability, the relative stability at finite temperatures and time evolution and devolution kinetics in a non-equilibrium state. Electronic structure calculations, the cluster variation method and the path probability method are proposed as potential theoretical tools, respectively, for each category. A number of examples of our previous calculations are presented to demonstrate that these methods are fully compatible and provide a sound basis for a general framework of the phase stability theory of intermetallic compounds.

The cluster variation method of equilibrium thermodynamics is employed to calculate the Ll0-disorder phase diagram. The stability analysis based on the second-order derivative of the free energy functional with respect to the deviation of correlation functions from their equilibrium values yields the 〈100〉 instability locus in the phase diagram. The time evolution of cluster probabilities at the phase transition is investigated on the basis of the path probability method of non-equilibrium statistical mechanics. Thereby the synthetic study of thermodynamics and kinetics based on the cluster variation method and the path probability method is attempted. It is shown that the fluctuation is necessary to drive the ordering reaction above the instability temperature, whereas the spinodal-like ordering transition takes place below the instability temperature. The extension of the present study of a spin system to an alloy system is briefly discussed and a critical problem to be settled is pointed out.

The morphology of anti-phase domains (APDs) formed during melt-quenching in binary and ternary Ni3Al alloys is carefully examined and the similarity with those observed in Cu3Pt during heterogeneous ordering is discussed. It is first shown that the morphology of APD in melt-quenched Ni3Al alloys often varies from fine equiaxed in the grain interior to elongated stripes towards grain boundaries. There have been similar observations by previous investigators, in which the difference in the APD morphology has been attributed the microsegregation of aluminum to provide a local difference in the order-disorder transition temperature relative to the freezing point. On the other hand, the present authors have shown that in Cu3Pt having order-disorder transition temperature, the similar elongated stripe-like APDs were formed during isothermal annealing, as a result of heterogeneous ordering, and that their growth involved grain boundary migration. Then the possibility is pointed out that APD morphology observed in melt-quenched Ni3Al would, in part, be relevant to the formation and growth processes of APDs found in Cu3Pt.

The CoAlC ternary phase diagram has been experimentally examined for the Co-corner with a particular interest in phase relations among cobalt primary solid solutions, denoted as (Co), the E21 type intermetallic compound Co3AlC, and the B2 type CoAl. Liquidus surface composed with monovariant and contour lines, and corresponding reaction scheme were determined by optical microscopy, differential thermal analysis, X-ray diffraction, and energy dispersive X-ray spectroscopy. Several isothermal sections and isoplethals with respect to a fixed concentration for one of the elements were also evaluated. It is shown that such multiphase alloys as B2/E21, B2/(Co), and B2/E21/(Co) can be produced in the ternary system by proper choices of alloy chemistry and heat treatment.

Thermal conductivity measurement by the laser-flash method adopted here is very suitable for intermetallic compounds, some of which are too brittle for preparing samples with good geometry. Thermal conductivity data at room temperature are presented in the series of aluminides, FeAl, CoAl and NiAl, titanides, FeTi, CoTi and NiTi, and gallides CoGa and NiGa, in order to reveal the role of 8A group elements of the first transition metal series. Thermal conductivity reaches a maximum at stoichiometry and decreases with deviations from stoichiometry on either side in most of these compounds. The largest thermal conductivities observed are 92 W m−1 K−1 of NiAl among the aluminides, 23 of NiGa among the gallides and 73 of FeTi among the titanides. It is discussed that the thermal conductivity is further reduced as the position of the partner components becomes distant from that of a host component.

Thermal conductivity of Ni3Ga-X ternary alloys was comprehensively surveyed for 16 kinds of ternary elements X. The direction of ridge in thermal conductivity contours in γ′ single phase field agrees with that of solubility lobe of γ′ phase in a ternary phase diagram. The ridge direction is determined by the sublattice occupation of a ternary element.

The effect of Mn addition on the mechanical properties of TiAl base alloys was examined by compression test for Ti-35mass%Al, Ti-36mass%Al and Ti-34.5mass%Al-1.45mass%Mn alloys in the temperature range of 296 to 1 073 K at strain rates of 10-1 to 10-4 sec-1. Mn addition to the TiAl alloy increased the proof stress and improved the deformability at both room temperature and high temperatures. The proof stress of the TiAl alloy containing Mn had the positive temperature dependence for both the as-cast and the heat-treated alloys. The reason for the positive temperature dependence of the proof stress in the as-cast alloy is different from that in the heat-treated alloys, i.e. in the former it is due to a large amount of Ti3Al phase and in the latter alloy it is due to the decrease of the Al content in TiAl phase. The as-cast alloy containing Mn deformed soundly at 1073 K at a strain rate of 10-1 sec-1 and had the compressive strain of more than 50%.

With ternary Ni-40at%Co-X alloys the solid-solution hardening (ssh) due to solutes X of transition-metal group (TM) elements like Ta and Nb and of B-subgroup (B) ones like Sn and Al was investigated. The results were compared with the previous study on the ssh of pure Ni. The value of ssh, Δσ, for a solute X in the Ni-Co alloy is greater than that for X in pure Ni. This increase in Δσ, however, is not explicable in terms of the changes in size-misfit and shear modulus with alloying Co in Ni solvent because these changes are not so great. Instead, for the ssh normalized by the size-misfit, there found a trend of it being greater in the order of the alloy group (A) of Ni-X making a continuous solid solution, the group (B) of Ni-X having a solid solubility, and the group (C) of Ni-Co-X having a smaller solid solubility than that for the group B. This suggests that the increase in the normalized ssh for the Ni-Co-X alloy might be deeply related with the reduction in solid solubility due to the addition of Co. A probable reason for this has been discussed.

Solid solution hardening in Ni-Co, Ni-Pd and Ni-Fe binary matrix alloys is investigated mainly by the addition of Nb and the results are compared with that in nickel. It is shown that the rate of solid solution hardening per 1at% of Nb is larger in the following order; Ni-Co, Ni-Fe>Ni>Ni-Pd. Since there is no appreciable difference in the size misfit parameter of Nb in these alloy systems, such difference cannot be interpreted solely by the elastic interaction theory. To be noted is the fact that the limit of solid solubility of Nb would be reduced in Ni-Co and Ni-Fe alloys but be increased in Ni-Pd alloy both as compared to that in Ni. Then the limit of solid solubility is shown to be well correlated with the magnitude of the interaction parameter between the solute and the solvent. If it is large negative, there should be a strong tendency for the solution to have a short range order and if it is large positive the solute atoms should tend to form clusters. In relation to the limit of solid solubility, it is suggested that in Ni-Co and Ni-Fe alloys dislocations would no more be interacting with discrete single solutes distributed randomly but with some kind of solute aggregates to cause the extra hardening as compared to Ni.

Copolyesters (CPEs) prepared by the transesterification reaction between aromatic and aliphatic polyesters were hydrolyzed by Rhizopus delemar lipase. The susceptibility of CPEs to hydrolysis by this lipase dropped off rapidly during the initial stage of the transesterification reaction and increased gradually as the reaction proceeded. The susceptibility to hydrolysis decreased with increase in aromatic polyester content. It was concluded that the rigidity of the aromatic ring in the CPE chains strongly influenced their susceptibility to hydrolysis by this lipase.