Improvements in Alloys of Aluminium and Magnesium.
Year: 1899

page_text: À communication from abroad by Dr. LUDWIG MACH, of Villa Brueninghaus,
Kalaische Strasse, Jena, Germany.
Improvements in Alloys of Aluminium and Magnesium.
1. ALFRED GEORGE BROOKES, of 55 and 56, Chancery Lane, in the County of
London, Chartered Patent Agent, do hereby declare the nature of this invention
to be as follows: --
In an application for Letters Patent made by me on Nov. 25 last, 24878 1909,
there is described an alloy of aluminium and magnesium, which has this feature
in common with pure aluminium, that its specific gravity is very inconsiderable:
while it is superior to pure aluminium by reason of its extraordinary capacity for
being worked."
"
Now apart from this "workability," the question as to how far a metal alloy can
be made serviceable in practice, in certain cases involves also the melting point
of such alloy.
In view of this, the present invention relates to an alloy of aluminium and
magnesium, the point of fusion of which is raised in a very marked degree by
suitable admixtures.
The point of fusion of an alloy of aluminium, and magnesium containing from
10 to 30 paris of magnesium to every 100 parts of aluminium lies somewhere
about 7000 Centigrade: but for certain purposes, for which such "workable"
alloys may have to be employed, it is necessary to raise their melting point above
that temperature, without however affecting their mechanical properties.
This result may be but imperfectly attained by somewhat considerable additions
of copper, wolfram, chrome, and nickel: for, while by the addition of these
metals in effective proportions, the alloy is certainly rendered more difficult of
fusion than it would otherwise be, yet at the same time its weight (or specific
gravity) is increased, and it also becomes far more brittle; so that, on the upshot,
some of its most valuable qualities are sacrificed.
Now in the course of experiments made with a view to ascertaining the influence
of sundry metallic additions upon aluminium-and-magnesium alloys, it has been
found that zine, tin, cadmium and bismuth do not raise the melting point of the
alloy, but that they render such alloy somewhat softer and less resistant;
while the admixture of even inconsiderable quantities of antimony does elevate
the melting point of the alloy in question in a surprisingly high degree.
A pure alloy of aluminium and magnesium, on being brought to a dark (or deep)
red heat, is fluid, and contunues so, even when its surface begins to glitter like
mercury. When cast in this condition, the castings obtained are perfect as regards
density: the moulds, and even air-passages not exceeding 5 millimetres in width,

page_text: being entirely filled up by the metal; so that, on the whole, the behaviour of the
alloy is the same as that of pure aluminium.
Now if a piece of antimony be added to the red-hot alloy in the crucible, such
alloy will become semi-fluid, first, around the antimony in process of fusion;
after which, according to the amount of antimony added, the thickening effect
will pervade the whole of the liquified metallic mass, until it becomes of the con-
sistency of paste throughout, so that the stirring rod stands upright in it.
:
The fire should then be intensified ; and not until a white heat is attained
will the thick mass become fluid, and the antimony fully dissolved; this alloy
may be used for castings in a white-hot (or incandescent) condition only.
The attitude of the castings obtained, as regards their mechanical properties,
will be the same as that of pure aluminium-and-magnesium alloys, while they will
be notable for their imporosity; whereas castings of incandescent alloys of
aluminium and magnesium only are mostly somewhat deficient in density, a fact
which must be ascribed to the evaporation of the magnesium they contain.
The incomparably greater fire-resisting property (or refractoriness) of this alloy
is evidenced by the chips which resist the flame of the Bunsen-burner better than
those of the pure alloys of aluminium and magnesium.
Antimony, therefore, supplies a means for raising the point of fusion of
aluminium-and-magnesium alloys without injuriously affecting their valuable
mechanical properties.
Now this is how the preparation of the (improved) alloy is best proceeded with;
antimony is first melted in the aluminium, which has been fused under a pro-
tecting roof; then magnesium is added to the metal in fusion, in small lumps.
The moment the magnesium begins to melt, the fluidity of the metal becomes
slow; as more magnesium is supplied, the metal gradually acquires the consistency
of paste; and not until its temperature is raised to a white heat, will its fluidity be
restored.
It is important, in fusing this alloy, to employ stirrers of clay or porcelain only,
as iron stirrers will quickly melt.
The melting point of pure aluminium, also, may be raised somewhat by sub-
stantial additions, say, about 25 per cent. of antimony, as has been ascertained by
tests; but not in anything like the degree in which this can be done in the
case of an alloy of aluminium and magnesium by considerably smaller additions of
that metal viz. from 10 to 15 per cent. Aluminium, mixed with, say,
25 per cent. of antimony becomes fluid when brought to a red heat, while an
aluminium-and-magnesium alloy containing 100 parts of aluminium and 20 parts
of magnesium mixed with from 10 to 15 per cent. of antimony, does not liquify
until heated to a white heat.
For practical purposes, all alloys of aluminium, magnesium and antimony,
containing to every 100 parts of aluminium, from 2 to 30 parts of magnesium and
from 2 to 35 parts of antimony, will prove serviceable, according to the greater
or less percentage of magnesium it contains, the material will be more or less
pliant, and according to the greater or less proportion of antimony; its melting
point will be higher or lower.
Thus the behaviour of the alloy of aluminium and magnesium towards antimony
is different from that of pure aluminium.
WM. BROOKES & SON.
55 and 56, Chancery Lane, London. Agents for the Applicant.

page_text: Kalaische Strasse, Jena, Germany.
Improvements in Alloys of Aluminium and Magnesium,
I, ALFRED GEORGE BROOKES, of 55/56, Chancery Lane, in the County of
London, Chartered Patent Agent, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:→
The object of my invention is a new and improved alloy of aluminium, mag-
nesium and antimony.
Alloys of aluminium and magnesium as regards tenacity, ductility, hardness and
so on are exceedingly sensitive to small additions of heavy metals for instance of
iron, manganese, nickel, cobalt, chromium, tungsten, molybdenum, uranium and
many others; also phosphorus, arsenic and antimony raise the ductility of the
alloy.
Some of those metals as copper and nickel are easily dissolved in the alloy of
aluminium and magnesium; if others however are made use of such as chromium,
tungsten. molybdenum, manganese and cobalt, at first the alloys of these metals
with aluminium must be produced and then magnesium is to be added.
The latter metals when added in relatively great quantities render the alloys
more brittle, raise the melting point and require that in consequence of their diffi-
culty of fusion the metals must be cast in a hotter condition.
A pure alloy of aluminium-magnesium, on being brought to a dark (or deep)
red heat, is thin fluid, and continues so. even when its surface begins to glitter
like mercury. When cast in this condition, the castings are perfect as regards
density; the moulds and even air-passages not exceeding 05 mm. in width, being
entirely filled up by the metal so that, on the whole, the behaviour of the alloy is
the same as that of pure aluminium.
Antimony exerts a special influence on the melting process.
If a piece of this metal be added to the red-hot alloy of aluminium and mag-
nesium, such alloy will become semi-fluid, first, around the antimony; after which,
according to the amount of antimony added, the thickening effect will pervade the
whole of the metallic mass, until it assumes the consistence of paste throughout,
so that the stirring rod stands upright in it. The fire should then be intensified.
and when a white heat is attained the thick mass becomes fluid again, and
the antimony being fully dissolved; this alloy may be used for castings in a red-hot
condition. The castings obtained, as regards their mechanical properties, are
nearly equivalent to castings of pure aluminium-and-magnesium alloys and are
remarkable for their imporosity: whereas castings of alloys of aluminium and
magnesium without an addition of antimony, when cast at red heat, are liable to
be somewhat deficient in density.
Antimony (melting point 430°Centigrade) therefore supplies a means for raising
the point of fusion of aluminium-and-magnesium alloys without disadvan-
tageously affecting their valuable mechanical properties; the specific gravity, as
must be admitted, somewhat increases.
Now this is how the preparation of the improved alloy is best proceeded with:
magnesium is first melted or dissolved in the aluminium which has been fused
with or without the use of a protecting cover, then antimony is added to this alloy
in small lumps. The moment the antimony begins to melt, the fluidity of the
metal becomes slow; as more magnesium is supplied the metal gradually acquires

page_text: the consistency of a paste; and not until its temperature is raised to a white heat
will its fluidity be restored.
If small quantities of antimony are added to pure aluminium the fracture of this
alloy becomes grey and similar to cast iron and the melting point may be raised
somewhat by substantial additions, say about 25 per cent. of antimony, as has been
ascertained by tests; but not in anything like the degree in which this can be done
in the case of an alloy of aluminium and magnesium by considerably smaller addi-
tions of that metal, air from 10 to 15 per cent. Aluminium mixed with, say
25 per cent of antimony becomes fluid when brought to a red heat, while an
aluminium and magnesium alloy containing 100 parts of aluminium and 20 parts
of magnesium, mixed with from 10 to 15 per cent. of antimony does not liquefy
until heated to a very light red-heat.
Thus the behaviour of the alloy of aluminium and magnesium towards antimony
is different from that of pure aluminium.
According to the special purposes for which the alloy is intended I may vary
the quantity of its components. I prefer to use alloys of 100 parts of aluminium, 2
to 30 parts of magnesium and 0'5 to 40 parts of antimony.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
:-
An aluminium-magnesium alloy comprising 100 parts of aluminium, 2 to 30 parts
of magnesium and 05 to 40 parts of antimony, substantially as described.
Dated the 24th day of July 1899.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.