Certain non-magnetizable alloys of nickel, chromium-nickel and chromium-manganese were rendered magnetizable by annealing.
The majority of alloys, when examined thus, prove to be complexes of two or more materials, and the patterns showing the distribution of these materials throughout the alloy are of a most varied character.
Photomicrographs Of Alloys And Metals.
The cadmium molecule, as shown by determinations of the density of its vapour, is monatomic. The metal unites with the majority of the heavy metals to form alloys; some of these, the so-called fusible alloys, find a useful application from the fact that they possess a low melting-point.
Some are in Greek and demotic, and one, of peculiar interest from the chemical point of view, gives a number of receipts, in Greek, for the manipulation of base metals to form alloys which simulate gold and are intended to be used in the manufacture of imitation jewellery.
The author of these receipts is not under any delusion that he is transmuting metals; the MS. is merely a workshop manual in which are described processes in daily use for preparing metals for false jewellery, but it argues considerable knowledge of methods of making alloys and colouring metals.
Later, however, as in the Commentary on this work written by Synesius to Dioscorus, priest of Serapis at Alexandria, which probably dates from the end of the 4th century, a changed attitude becomes apparent; the more practical parts of the receipts are obscured or omitted, and the processes for preparing alloys and colouring metals, described in the older treatise, are by a mystical interpretation represented as resulting in real transmutation.
Other branches of this subject are treated in the articles Chemical Action; Energetics; Solution; Alloys; Thermochemistry.
The Egyptians obtained silver, iron, copper, lead, zinc and tin, either pure or as alloys, by smelting the ores; mercury is mentioned by Theophrastus (c. 300 B.C.).
Other alloys may be produced, such as bronze, or German silver, by selecting solutions (usually cyanides) from which the current is able to deposit the constituent metals simultaneously.
Of the alloys the following may be named: With Antimony.
Magnetic Properties of Alloys and Compounds of Iron.
Iron and its alloys, including the various kinds of steel, though exhibiting magnetic phenomena in a pre-eminent degree, are not the only substances capable of magnetization.
Practically the metals iron, nickel and cobalt, and some of their alloys and compounds constitute a class by themselves and are called ferromagnetic substances.
In the case of the ferromagnetic metals and some of their alloys and compounds, the permeability has generally a much higher value.
Became definite and cyclic. When the permanent magnetic condition had been thus established, it was found that in the case of all the metals, except the two alloys containing large percentages of nickel, the magnetic moment was temporarily increased by cooling to - 186°.
Alloys of Nickel and Iron.
Alloys containing different proportions of nickel were found to exhibit the phenomenon, but the two critical temperatures were less widely separated.
They found that the hysteresis-loss, which at ordinary temperatures is very small, was increased in liquid air, the increase for the alloys containing less than 30% of nickel being enormous.
Steinmetz's formula applies only for very weak inductions when the alloys are at the ordinary temperature, but at the temperature of liquid air it becomes applicable through a wide range of inductions.
Alloys And Compounds Of Iron In 1885 Hopkinson (Phil.
Soc., 1890, 48, 1) also noticed some peculiarities of an unexpected nature in the magnetic properties of the nickel-steel alloys already referred to.
The permeability of the alloys containing from 1 to 4.7% of nickel, though less than that of good soft iron for magnetizing forces up to about 20 or 30, was greater for higher forces, the induction reached in a field of 240 being nearly 21,700.
The magnetic qualities of various alloys of iron have been submitted to a very complete examination by W.
The following table gives the exact composition of some alloys which were found to be non-magnetizable, or nearly so, in a field of 320.
A very small difference in the constitution often produces a remarkable effect upon the magnetic quality, and it unfortunately happens that those alloys which are hardest magnetically are generally also hardest mechanically and extremely difficult to work; they might however be used rolled or as castings.
A number of iron alloys have been examined by Mme.
Magnetic Alloys of Non-Magnetic Metals.-The interesting discovery was made by F.
Heusler 2 in 1903 that certain alloys of the non-magnetic metal manganese with other non-magnetic substances were strongly magnetizable, their susceptibility being in some cases equal to that of cast iron.
In all such magnetizable alloys the presence of manganese appears to be essential, and there can be little doubt that the magnetic quality of the mixtures is derived solely from this component.
If this view is correct, it may also be possible to prepare magnetic alloys of chromium, the only other paramagnetic metals of the iron group.
By the early Greek alchemists the metal was named Hermes, but at about the beginning of the 6th century, it was termed Zeusor Jupiter, and the symbol 2(assigned to it; it was also referred to as diabolus metallorum, on account of the brittle alloys which it formed.
On the one hand he worked out the general theory of the magnetic circuit in the dynamo (in conjunction with his brother Edward), and the theory of alternating currents, and conducted a long series of observations on the phenomena attending magnetization in iron, nickel and the curious alloys of the two which can exist both in a magnetic and non-magnetic state at the same temperature.
Alloys of magnesium and silicon are prepared by heating fragments of magnesium with magnesium filings and potassium silico-fluoride.
The compounds formed in the first case, which may be either definite chemical compounds or solid solutions, are discussed under Alloys; in this place only combinations with non-metals are discussed, it being premised that the free metal takes part in the reaction.
Alloys of copper and silicon were prepared by Deville in 1863.
It is also a constituent of many valuable alloys; brass, Muntz-metal, pinchbeck, tombac, are examples.
Carbon rods, bound together at the outer end by being cast into a head of cast iron for use with iron alloys, or of cast copper for aluminium bronze.
The reduced aluminium alloys itself immediately with the fused globules of metal in its midst, and as the charge becomes reduced the globules of alloy unite until, in the end, they are run out of the tap-hole after the current has been diverted to another furnace.
It was mainly for the sake of their patina that value attached to the remarkable alloys shakudo (3 parts of gold to 97 of a Ba.
The term "alloy" does not necessarily imply obedience to the laws of definite and multiple proportion or even uniformity throughout the material; but some alloys are homogeneous and some are chemical compounds.
But modern work has shown that, although alloys sometimes contain solid solutions, the solid alloy as a whole is often far more like a conglomerate rock than a uniform solution.
For example, if vapours of the volatile metals cadmium, zinc and magnesium are allowed to act on platinum or palladium, alloys are produced.
Fromm have shown that alloys may be precipitated from dilute solutions by zinc, cadmium, tin, lead and copper.
They have also formed in this way certain alloys of definite composition, such as AuCd 3, Cu 2 Cd, and, more interesting still, Cu 3 Sn.
But these methods of forming alloys, although they suggest questions of great interest, cannot receive further discussion here.
Our knowledge of the nature of solid alloys has been much enlarged by a careful study of the process of solidification.
All these mixtures when solidified may fairly be termed alloys.'
6 gives the freezing-point diagram for alloys of lead and tin.
The two sloping lines cutting at the eutectic point are the freezing-point curves of alloys that, when they begin to solidify, deposit crystals of lead and tin respectively.
If we examine alloys on the tin side we shall find large crystals of tin embedded in the same complex.
But the occasional or indeed frequent existence of chemical compounds in alloys has now been placed beyond doubt.
Thus, a number of copper-tin alloys when digested with hydrochloric acid leave the same crystalline residue, which on analysis proves to be the compound Cu 3 Sn.
There are thus two eutectic alloys B and D, and the alloys with compositions between B and D have higher melting-points.
It is probable that all the alloys of compositions between B and D, when they begin to solidify, deposit crystals of the compound; the lower eutectic B probably corresponds to a solid complex of mercury and the compound.
This is the case with the copper-tin alloys containing less than 9% by weight of tin; a microscopic examination reveals only one material, a copper-like substance, the tin having disappeared, being in solution in the copper.
The intermediate summits occurring in the freezing-point curves of alloys are usually rounded; this feature is believed to be due to the partial decomposition of the compound which takes place when it melts.
- These triple alloys are noted for their low fusing points.
It is certain that the structure existing in the alloy is closely connected with the mechanical properties, such as hardness, toughness, rigidity, and so on, that make particular alloys valuable in the arts, and many efforts have been made to trace this connexion.
These efforts have, in some cases, been very Alloys: Fro.