Eutectic alloying

Table 13. High Temperature Eutectic Alloy Compositions...

An important example of an MMC in situ composite is one made by directional solidification of a eutectic alloy. The strength, (, of such an in situ metal-matrix composite is given by a relationship similar to the HaH-Petch relationship used for grain boundary strengthening of metals ... 

These relays also possess characteristics similar to those of a bimetallic relay and closely match the motor heating and cooling curves. They are basically made of a low-melting eutectic alloy which has defined melting properties. The alloy, with specific proportions of constituent metals such as tin, nickel and silver, can be made for different but specific melting temperatures. This property of the alloy is used in detecting the motor s operating conditions. 

Since the operation of the eutectic alloy relays depends upon the magnitude of heating, which is a function of current and time, these relays also give an inverse current-time characteristics. 

Slides Microstructures of oxide layers and oxide-resistant coatings on metals and alloys selective attack of eutectic alloys [5]. 

A hyper-eutectic alloy containing, say, 50% Sb starts to freeze when the temperature reaches the liquidus line (point a in Fig. 20.39). At this temperature pure pro-eutectic Sb nucleates as the temperature continues to fall, more antimony is deposited from the melt, and the composition of the liquid phase moves down the liquidus line to the eutectic point. When this is reached, the remainder of the melt solidifies. The microstructure of alloys of eutectic composition varies somewhat with alloy system, but generally consists of an aggregate of small particles, often platelets, of one of the phases comprising the eutectic in a continuous matrix of the other phase. Finally, the microstructure of the hypereutectic 50% Sb alloy already mentioned... 

Binary liquid metal systems were used in liquid-metal magnetohydrodynamic generators and liquid-metal fuel cell systems for which boiling heat transfer characteristics were required. Mori et al. (1970) studied a binary liquid metal of mercury and the eutectic alloy of bismuth and lead flowing through a vertical, alloy steel tube of 2.54-cm (1-in) O.D., which was heated by radiation in an electric furnace. In their experiments, both axial and radial temperature distributions were measured, and the liquid temperature continued to increase when boiling occurred. A radial temperature gradient also existed even away from the thin layer next to the... 

Fusion welding is possible because copper, a component of most gold and silver alloys, easily forms eutectics, alloys that melt at a temperature lower than any of the metals composing them (Duval et al. 1989 Wolters 1983, 1981). To attach granules or wires to a surface of gold or silver alloy... 

Fig. 5 Schematic representation of LAJs based on liquid metal electrodes, (a) The two Hg drops junction. The drops are extruded from two microsyringes and covered singularly by similar or different SAMs before being brought in contact, (b) An Hg-drop electrode covered by SAM(l) (usually formed by hexadecane thiol) is brought in electrical contact with a SAM(2) formed on a solid metal surface, (c) A drop of In/Ga eutectic alloy (E-Gain) contacts a SAM formed on a solid electrode surface...

Recently, Whitesides et al. [88, 164, 165] have replaced Hg with an In/Ga eutectic alloy (E-Gain) (Fig. 5c). In/Ga alloy-based electrodes present few advantages related to (1) the lower affinity for the bottom Au or Ag electrode, so that the junction can be assembled in air, (2) low toxicity and (3) good processability and mouldability. These characteristics indicate E-Gain electrodes as possible candidates for incorporation into functional devices. Some disadvantages are related to the surface of the In/Ga alloy (1) unlike Hg, it is not atomically flat and (2) it forms in few minutes a discontinuous layer of oxide [81]. 

Europium(III) reduction, 14 640 Eutectic alloys, solidification of, 16 173 Eutectic temperature, of sodium... 

Uses. It is used as a getter it has a relatively low vapour pressure and is very reactive towards H2, 02, N2, C02, H20, etc., even removing inert gases by inclusion. It is used as de-oxidizer for steel, etc. and also as modifying agent of Al-Si eutectic alloys (as Na and Sr). 

Uses. Indium finds application in making low melting alloys the eutectic alloy indium-gallium (14.2 at.% In, 21.4 mass% In) melts at 15.3°C. In is used as an additive to solder alloys to improve malleability at low temperature and corrosion resistance it is also used in dental alloys, in the preparation of semiconductors, etc. 

A. Karty, J. Grunzweig-Genossar, P.S. Rudman, Hydriding and dehydriding kinetics of Mg/ MgjCu eutectic alloy Pressure sweep method, J. Appl. Phys. 50 (1979) 7200-7209. 

Ref 1), The term is generally applied to alloys melting below 450°F(233°C). They can be binary, ternary, quaternary, or quinary mixts of Bi, Pb, Sn, Cd, Indium and less frequently other metals. Eutectic alloys are relatively few in number and are the particular compns that have definite and minimum mp as compared with other mixts of the same metals. Table I of Ref 2 lists 17 eutectics of mp s ranging from 46.89° to 248.0°C. Of these the Lipowitz s eutectic, melting at 70.0° is well known. It consists of Bt 50, -Pb 27, Sn 13 Cd 10%. Table II of Ref 2 lists 13 non-eu ectic alloys with mp s ranging from 64.0 to 1J9°C. Table III of Ref 2 lists eight common fusible alloys of mp s 70 to 138°. Of... 

Bismuth Alloys. Bismuth is a component of a number of low-melting alloys. Kirk Othmer (Ref 1) have listed eutectic alloys melting below 200° and a few non-eutectic alloys that are used extensively in industry... 

While we have not yet carried out detailed kinetic measurements on the rate of photocorrosion, our impression is that the process is relatively insensitive to the specific composition of the strontium titanate. Trace element compositions, obtained by spark-source mass spectrometry, are presented in Table I for the four boules of n-SrTi03 from which electrodes have been cut. Photocorrosion has been observed in samples from all four boules. In all cases, the electrodes were cut to a thickness of 1-2 mm using a diamond saw, reduced under H2 at 800-1000 C for up to 16 hours, polished with a diamond paste cloth, and etched with either hot concentrated nitric acid or hot aqua regia. Ohmic contacts were then made with gallium-indium eutectic alloy, and a wire was attached using electrically conductive silver epoxy prior to mounting the electrode on a Pyrex support tube with either epoxy cement or heat-shrinkable Teflon tubing. 

E. Heyn and O. Bauer s f.p. curve is shown in Fig. 21. A. H. Hioms gave 620° for the eutectic temp, with 8-2 per cent, of phosphorus. The f.p. of copper is steadily depressed by additions of phosphorus from the f.p. of pure copper to that of the eutectic the f.p. curve then rises to the saturation point with 14 per cent, of copper. The eutectic alloy shows the characteristic pearlitic structure with copper in excess, the metal shows islands of copper surrounded by the eutectic matrix and with an excess of phosphorus, crystals of copper tritaphosphide, Cu3P, also surrounded by the pearlitic eutectic matrix. 

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