Liquid metal

It might already be hiding in the DoD apps --- if it's as good as is claimed, it's ideal for bearings, gears, shafts, and other components in high throughput mechanical power transmission applications --- couple more knots for the Navy's bathtub toys, little more performance here and there for the other services.


First addendum: Low thermal expansion coefficient for gauging and measurement applications, kinematic mounts, optical benches, precision valves; chemical process equipment.

 

Didn't read it all, but it sounds neat!

 

wow :)
thats really cool!

just got too interested about it and found even a site where u can order those tubes etc :)

and those weren't golfballs bouncing.. just plain ball bearings.

 

Quenching a material rapidly to prevent a ordered microscopic arrangement is not a new concept. In fact, blacksmiths in forges of the Middle Ages were working along a similar principle by repeatedly heating a blade, hammering it and quenching it.

The theory is that the work hardening introduces deformations/dislocations into the microscopic structure. At elevated temperatures, large, crystalline grains will re-nucleate about these dislocations. So you get a finer grain structure. Quenching it effectively locks the changes in place.

Regardless, one major disadvantage of metals with an amorphous microstructure formed by quenching is that they are an unstable alloy. Basically, if you leave them for some time, their microstructure will slowly change, reverting back to a crystalline structure. This effect is even worse at elevated temperatures, because the reorganising of the microstructure is mostly a diffusion governed process, thus controlled by Arrhenius' Law.

This process basically limits the applications of such materials to lower temperature operations (e.g. not in engines). If they are implemented in high temperature applications, they must be continuously monitored/replaced.

Their improved strength/weight ratio comes partly from their lower densities due to poorer atomic packing. The high hardness/yield strength from the lack of any slip lines, like grain boundaries. Their allegedly higher corrosion resistance and wear resistance claims are a bit dubious. Thermodynamically speaking, the atoms in an amorphous metal are at a higher energy state than a crystalline one, meaning that they should be more reactive. Sort of like how a lump of marble will react slower than powdered marble with acid. The 'higher' wear resistance could be due to them comparing a tool made monolithically out of LiquidMetal rather than with a (as is typically done) surface treated tool. A surface treated tool is like a tooth - hard enamel with a relatively softer dentine. Once you breach the hard surface the tool loses its wear resistance. Obviously, a monolithic part made out of a single material with only average wear resistance may well have a higher overall wear resistance than one with just a hard coating.

 

Incidentally, I would like to see comparisons between the yield strengths of such LiquidMetals and monocrystalline materials, such as those used in turbine blades of high performance aero engines.