M. B. Bever

An x-ray diffraction and calorimetric investigation of the compound Cu6Sn5

A phase transformation has been reported to occur at approximately 460 K in the compound Cu6Sn5, which has the NiAs (B81 structure. Single-crystal and polycrystalline specimens of this compound were heat treated to produce the high-temperature Ŋ-phase and the low-tem-perature Ŋ’-phase. X-ray diffraction determinations confirmed that the transformation was of the type: Simple Superlattice Ŋ Long-Period Superlattice Ŋ’ An analysis proposed by Pauling for phases with the NiAs structure indicated that the nature of bonding in Cu6Sn5 is predominantly metallic. The heat of formation and the energy effect associated with the Ŋ-Ŋ’ transformation were measured by liquid metal solution calorimetry with tin as solvent. The heat of formation of the Ŋ’-phase is approximately —1.68 kcal per g-at., which also suggests metallic bonding. The energy effect of the Ŋ -Ŋ ’ transformation is approximately -0.06 kcal per g-at. and is consistent with the nature of the transformation of a simple superlattice to a long-period superlattice.

On the thermodynamic properties of the III–V compounds InSb, GaSb, and InAs

Abstract The heats of formation of the III–V compounds InSb, GaSb, and InAs at 0°C were measured by tin solution calorimetry. The heats of fusion of InSb and GaSb were measured by quantitative thermal analysis. From these measurements and published phase diagrams the excess free energies of the liquid phases in the systems In-Sb and Ga-Sb and the free energies of formation of InSb and GaSb were calculated by a method due to Wagner.

Short-range order and fermi surface effects in copper-rich copper-aluminum alloys

Abstract The diffuse scattering of X-rays has been measured in single crystals of Cu-Al alloys containing 6, 11 and 16 at. % Al. A pronounced diffuse satellite intensity with a four-fold symmetrical pattern about the normal f.c.c. superlattice positions was observed with the 11 and 16 at. % Al crystals. From the composition dependence of the satellite peak positions determined by other workers and by us, we show that these peaks have their origin in singularities, analogous to Kohn anomalies, which have previously been demonstrated in copper-gold alloys. This composition dependence provides a sensitive measure of the variation of the value of the Fermi wave vector in the 〈110〉 direction. The results agree with a simple scaling of the Fermi surface of copper. This interpretation is supported by measurements of positron annihilation in Cu-Al alloys reported by other investigators. The absence of anomalies and the near-randomness of the atomic arrangements at 6 at. % Al imply the existence of an order-disorder phase boundary, which is indicated by other data.

X-ray and calorimetric investigations of cold working and annealing of a gold-silver alloy

Abstract Calorimetric and X-ray diffraction line-broadening measurements were carried out on samples of a 75Au–25Ag (weight per cent) alloy deformed by filing and annealed at various temperatures up to 500°C. Stored energy, hardness, subgrain size, local strain, and short-range order determinations were made. It appears that most of the stored energy is associated with the presence of subboundaries; a small fraction of the energy is attributable to a reduction in the short-range order and a negligible amount is stored in the local elastic distortions. The recovery process involves a substantial reduction of the local strains and a small increase in the subgrain size in this alloy. Recrystallization appears to involve a removal of the low-angle boundaries and the complete elimination of the local strains.

Liquid Metal Solution Calorimeter

A liquid metal solution calorimeter and its operation are described. The method of calculation is outlined and the sources of error are analyzed. In this calorimeter, heat effects upon dissolution of samples in liquid metals are measured; heats of solution are determined directly and heats of formation, energies of ordering, and the stored energy of cold work are found by a difference method. The calorimeter operates in the temperature range 240 to 450°C; samples are added from 0 or −195°C. Highest accuracy, of the order of ±2 cal/g‐atom, is attained with suitably chosen solute‐solvent combinations giving very small total heat effects upon dissolution.

The thermoelastic effect in iron and nickel as a function of temperature

The adiabatic thermoelastic temperature change was determined as a function of temperature and stress in nickel and Armco iron. The results are in agreement with an equation first derived by Lord Kelvin. Near the Curie temperature the thermoelastic effect changes appreciably. Calculations confirm that the thermal expansion coefficient of iron decreases in the vicinity of the Curie temperature as predicted by the theory of ferromagnetism.

The Energy Stored in Metal Chips during Orthogonal Cutting

Chips of a gold‐silver alloy were made by orthogonal cutting with apparatus which permitted the determination of the chip geometry and cutting forces. From these data the stresses and strains and the shear and friction energies were calculated. Three rake angles were used to obtain different shear strains. The energy stored in the chips was determined as the difference in the heat effects associated with the dissolution in liquid tin of samples of cold worked and annealed chips in an isothermal calorimeter of high precision. With increasing strain the stored energy increased, but the ratio of the stored energy to the shear energy decreased.

THE METASTABILITY OF GOLD-ANTIMONY PHASES PREPARED BY SPLAT COOLING.

Abstract The metastable gold-antimony phases ζ (h.c.p. Mg-A3 type) containing 15.0 at. % antimony and π (simple cubic α-Po-Ah type) containing 76.6% antimony were prepared by splat cooling. The heats of formation of these phases were measured by solution ealorimetry and their free energies of formation were estimated. An analysis of the free energies of the relevant phases leads to the following conclusions, (i) The phases ζ and π are unstable at all temperatures, (ii) Liquid alloys containing 15.0% and 76.6% antimony, respectively, must be undercooled by at least 150° and 200°K for the phases ζ and π to form, (iii) The temperature below which the π phase can form (600°K) is about 250°K lower than the temperature below which the ζ phase can form, (iv) Although the free energies indicate that the π phase is more unstable than the ζ phase, the calculated degrees of undercooling required and the calculated temperature of formation of the two phases indicate that the π phase is less difficult to produce by splat cooling than the ζ phase. This agrees with experimental observations.

The energy stored during the cold working of a gold-silver alloy

Abstract Strips of an alloy of 75 wt. per cent gold and 25 wt. per cent silver were cold worked by rolling. The stored energy was released by dissolution of the samples in liquid tin and found calorimetrically by comparison with annealed samples. The total energy expended in rolling was determined from a stress-strain diagram applicable to the rolling process. The stored energy increases with the strain, but shows a tendency toward saturation at high strains. The ratio of the stored energy to the total energy expended decreases at high strains.

The recycling of metals—II. Nonferrous metals

Abstract This paper treats the recycling of ferrous metals as an integral part of the iron and steel industry. The flows of home, prompt industrial and old scrap are analyzed. The industrial organization of ferrous scrap recycling is also described. Scrap is one of the two major raw materials of the iron and steel industry. The various steelmaking processes however, consume scrap in different ratios to other raw materials in the charge. The price sensitivity of scrap and the growing importance of automotive scrap are also considered. The advantages of using scrap in steelmaking include savings of energy, pollution abatement measures and processing which would otherwise be required in producing raw iron in the blast furnace. As a disadvantage, scrap can cause technical difficulties by introducing impurities into the steel. The paper also deals with international aspects of ferrous scrap markets. Finally, it assesses the supply-demand relation as a function of such developments as the shift in the balance of steelmaking processes, the adoption of continuous casting, the use of prereduced ores and further improvements in the processing of ferrous scrap.