Splat quenching is a

metallurgical Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...

, metal morphing technique used for forming metals with a particular crystal structure by means of extremely rapid

quenching In materials science, quenching is the rapid cooling of a workpiece in water, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such as ...

, or cooling. A typical technique for splat quenching involves

casting Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejecte ...

molten metal by pouring it between two massive, cooled copper rollers that are constantly chilled by the circulation of water. These provide a near-instant quench because of the large surface area in close contact with the melt. The thin sheet formed has a low ratio of volume relative to the area used for cooling. Products that are formed through this process have a crystal structure that is near-

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek language, Gr ...

, or non-crystalline. They are commonly used for their valuable magnetic properties, specifically high

magnetic permeability In electromagnetism, permeability is the measure of magnetization that a material obtains in response to an applied magnetic field. Permeability is typically represented by the (italicized) Greek letter ''μ''. The term was coined by Willi ...

. This makes them useful for

magnetic shielding In electrical engineering, electromagnetic shielding is the practice of reducing or blocking the electromagnetic field (EMF) in a space with barriers made of conductive or magnetic materials. It is typically applied to enclosures, for isolatin ...

and for low-loss

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

cores in

electrical grid An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:Kaplan, S. M. (2009). Smart Grid. Electrical Power ...

Procedure

The process of splat quenching involves rapid quenching or cooling of molten metal. A typical procedure for splat quenching involves pouring the molten metal between two cooled copper rollers that are circulated with water to transfer the heat away from the metal, causing it to almost instantaneously solidify. A more efficient splat quenching technique is Duwez's and Willen's gun technique. Their technique produces higher rates of cooling of the droplet of metal because the sample is propelled at high velocities and hits a quencher plate causing its surface area to increase which immediately solidifies the metal. This allows for a wider range of metals that can be quenched and be given amorphous-like features instead of the general iron alloy. Another technique involves the consecutive spraying of the molten metal onto a

chemical vapor deposition Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (subst ...

surface. However, the layers do not fuse together as desired and this causes

oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

s to be contained in the structure and pores to form around the structure. Manufacturing companies take an interest in the resultant products because of their near-net shaping capabilities.

Varying factors

Some varying factors in splat quenching are the drop size and velocity of the metal in ensuring the complete solidification of the metal. In cases where the volume of the drop is too large or the velocity is too slow, the metal will not solidify past equilibrium causing it to remelt. Therefore, experiments are carried out to determine the precise volume and velocity of the droplet that will ensure complete solidification of a certain metal. Intrinsic and extrinsic factors influencing the glass-forming ability of metallic alloys were analyzed and classified. Another alternative process to generate non-equilibrium structures or metallic glasses is the

melt spinning Melt spinning is a metal forming technique that is typically used to form thin ribbons of metal or alloys with a particular atomic structure. Some important commercial applications of melt spun metals include high-efficiency transformers (Amorp ...

process.

Product

Structure

The near-instantaneous

of the metal causes the metal to have a near-

crystalline structure, which is very uncharacteristic of a typical crystal. This structure is very similar to liquids, and the only difference between liquids and amorphous solids is the high

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

of the solid. Solids in general have a crystalline structure instead of an amorphous structure because the crystalline structure has a stronger binding energy. The way a solid can have the irregular spacing between its atoms is when a liquid is cooled below its melting temperature. The reason for this is the molecules do not have enough time to rearrange themselves in a crystalline structure, and therefore stay in the liquid-like structure.

Magnetic property

Amorphous solids in general have a unique magnetic property because of their atomic disorder as explained above. They are rather soft metals and each has its own specific magnetic property depending on the means of production. In the splat quenching process, the metals are very soft and have superparamagnetic properties or shifting polarity behavior caused by the rapid and intense heat transfer.

References