Russian magazine: "Young technician", November 1980


If we transform
metal in glass...

The operator has pressed the button, and from an aperture of an atomizer with huge speed the stream of the molten metal has departed. She falls on the moving smooth tape, which cooled by liquid helium, and immediately stiffens a thin silvery film and becomes … glass! In the end of the conveyor the film is curtailed on the coil into a roll.
… So in one of laboratories of the Central scientific research institute of ferrous metallurgy receive unusual


material. For the present he even does not have official name, conditionally he is called « metallic glass ». And hopes connect with it unusual …
Metal and glass … it is difficult to find, perhaps, more unlike against each other materials. But than to explain striking difference of their properties? Why glass transparent, very solid and fragile - if we hurl on floor, then it will be broken in little pieces? Question: Why the metal is solid, is pliant, malleable for shoeing? These questions though we talk about of absolutely different substances, are to some extent lawful. In fact the beginning of their way is identical - in the heated furnace. Moreover, and further the way of their transformation to a finished article in many respects is similar - we pressure the metal and the glass between platens of the rolling mill. Why they then have polarly of opposite properties?






Amorphous metals


We address for the help to physics which at once gives a principle explanation, - all cause in an internal structure of substance, in an positions of his atoms. At metals while fusion congeal, atoms will are built in the strict order, forming a so-called crystal lattice of the certain geometrical forms. In glass - both in molten stage and in cooled down - atoms are scattered in the chaotic disorder, scientists name it an amorphous structure of substance.
The location of atoms and determines, which substance we will have. There is a crystal lattice, then the substance will enough strong. The amorphous structure is a liquid or gas. Well but glass?.. It is hard, and is constructed as a liquid. The cause is that, the crystal lattice far not always the ideal form of location


of atoms, more precisely, she is good only when ideal. But such, alas, does not happen. Not each atom takes the place, allocated for him. The calculations show to us: on everyone of 15-20 thousand atoms one atom have stroll, so to say, in itself. His place in unit of a crystal lattice always freely. Moreover the lattice for the different reasons loses the strict form. It sharply worsens properties of metals - their real durability approximately in one thousand times less, than would be at an ideal crystal lattice!..
But what would happen with
metal, if at him there will be in general no crystal lattice?..
Scientists reflected on it for a long time. Theorists tell a different assumptions. For example, what for such material the corrosion can be absolutely not terrible!







After all she (corrosion) exist basically because of the same crystal structure of metal - begins on superficial borders of tiny grains-crystals, of which the surface of metal consists, the corrosion penetrate deep inside, and gradually destroying structure. Clearly, what benefits can be received if to deliver metal from a crystal lattice, if to make his structure amorphous, vitreous. After all, nobody still did not see of rusty glass! As to metal so today each fifth blast furnace in the world works only on refund of losses from corrosion!...
How to transform metal into similarity of glass? Metal in the molten condition, as well as hard glass, has no crystal lattice. She will arise in process of cooling, hardening of metal, and this process, if we not accelerate him by artificial cooling, can last hours. I.e. time is necessary on building of crystal structure from the chaotic disorder of atoms. But to be constructed whether the lattice if we do cooling of the metal instantly, for a second, or a split second? The employees of the central a scientific research institute of ferrous metallurgy decided to check up it of experimentally.
As have carried out superfast freezing the fused metal in this institute, we already saw: on the rushing tape cooled by liquid helium. Here we see hardenings with speed one million degrees a second! In other words, metal become hard during thousand split second! But … it still very little. In special design office of Institute of metallurgy of the Academy of Sciences the USSR A.A.Baykov's name have thought up also other way. There they spill the molten metal directly from the refractory crucible start up in the very thin gap between cooled copper cylinders. Freezing goes at once from both sides, therefore also speed of cooling much above -


millions degrees to a second!
The mechanism of this influence works by a principle of freeze frame at cinema: just all was in movement and has instantly fallen asleep in the most unexpected poses. So and here - atoms, instantly stoped, have not time for building the crystal lattice. The space cold fastens them to a place in that position in which they were in liquid.

The scientists expected much from received vitreous metal, but the reality has surpassed all expectations and assumptions. His properties turn out so, that scientists could not find for him other definition, except for "anomalous".
Firstly, we begin with corrosion properties - at amorphous metal, so how already and was predicted, unique corrosive resistance. The lorry body, would serve faithfully hundreds years without any greasings and coverings. This property is easily explainable: there are no grains in structure, and hence, and their borders where the rust arises. The amorphous structure, speaking figuratively, does not leave not the slightest chink for this artful enemy of metals. Already only one it can provide in the future for amorphous metals the broadest uses. But high anticorrosion property of metglas only one of his unprecedented properties.
Secondly, in comparison with usual steel the durability of metglas in tens times of greater! In addition he possesses remarkable magnetic properties, at magnetization - losses of energy are very small, ability to superconductivity… And many other properties, to which else is not found strictly theoretical explanation, will promise for creators of the future machines and devices new opportunities in industry. The history of a science and technology knows many examples, when opening of new materials with unusual properties led to colossal changes






in industry. So the microelectronics has begun with semiconductors. After origin of superconducting materials, development so-called cryogenic superelectrical engineering has begun.
New class of materials - amorphous metals and their alloys - still, so to say, in a cradle. But experts predict for them a fast step in practice, first of all in instrument-making. Transformers, the relay, various switches, magnetic screens - for these traditional devices amorphous materials with their unique properties big godsend. And if these and many other devices should work in the so-called extreme conditions, connected with low or heats, greater mechanical loadings, aggressive chemical environments, then these materials - a godsend doubly.
However, now even it is difficult to define borders of the future use of amorphous alloys. Certainly, at first they will find a place in devices already known to us. But later their new opportunities for certain will wake a design idea, and astonishing products, about which now visionary only dream, will start to descend from factory conveyors.
And besides, manufacture of a thin amorphous tape favourably differs from usual technology of metal works. Today it is necessary to do much work to transform metal


from ingot in a tape. First an ingot smooth out in thick strips on rolling mills, and repeatedly and with obligatory heating before every such smoothing. Later the strip will pickled in an acid to remove oven calx, later it is necessary to smooth a strip on other rolling mills in more thin tape, and periodically anneal her - it is necessary to remove from metal of the internal stress. And, at last, It is necessary to make on special cluster mill the final smoothing . All process - from reception of an ingot up to a ready tape - last some weeks… The amorphous multikilometer tape can be received during the one operation of forming during superfast cooling of liquid metal. It occupies only few minutes!
Whether it is possible to make from metglas an ingot, a volumetric detail? Today this question is not solved even in laboratories. And the tape from essentially new material is still absolutely unusual for technologists. Is not resolved also such elementary, apparently, the question: than we can cut amorphous alloys? We need to take into consideration, what they more strong and more firmly in comparison with any standard tool. Then are necessary the new tools which for the present no exist. And so almost all. But in fact so practical use of all openings and began…

A. VALENTINOV, the engineer