Add one part tin to nine parts of copper and you get bronze. Blend a tiny amount of carbon with iron and you get steel. The human race has been creating alloys for thousands of years. Now there’s a bunch of new alloys on the block. It looks like the traditional mixtures we’re familiar with are merely the tip of an awesome iceberg. Now a recipe that really shouldn’t work is creating metal mixtures with totally unexpected abilities.
Wild new metal mixtures set to revolutionise our world
Most everyday alloys blend a large amount of metal with a small amount of another metal. But that’s changing. According to an article in New Scientist magazine, metallurgists are busy making ‘wild’ new metal mixtures where no one element dominates. And the results are like nothing we’ve seen before. The resulting substances look likely to revolutionise everything from nuclear fusion reactors to jet engines, and the eggheads in the driving seat reckon they’re only just beginning to scratch the surface.
A lightbulb moment that changed alloys forever
The story begins in 1995 when Jien-Wei Yeh, a Taiwanese scientist, was idly mulling over why adding more than a strictly prescribed amount of one metal to another invariably resulted in weak, unworkable alloys. On an atomic scale, the extra atoms form clumps of metal within metal, and the material created is always horribly brittle. Yeh had one of those lightbulb moments that saw him racing back to the lab: might entropy deliver a work-around?
Entropy is a way to quantify disorder in a system. The rules of thermodynamics say the more disordered a system, the more stable it is. What would happen if he mixed a collection of metals together, instead of just adding small pinches of several metals to a large amount of another? If he mixed up equal proportions of elements, would the resulting substance be so disordered it’d have no chance of crumbling?
His hunch turned out to be right, and just a week later his research student had blended the first ever high entropy alloy. A year later the team had created more than forty new alloys, all remarkably hard and all resistant to corrosion. The only problem was, the team had no idea what they’d made. The alloys were so dramatically different from other materials that they had no data to help pin down the substances’ true nature.
Weird alloys with unexpected properties
Eight years later Yeh and his team had finally figured out, through painstaking experimentation and observation, how to interpret the data. He revealed his finding in 2004. Subsequent research by the scientific community has revealed a collection of new alloys with properties that were expected, and a load more with completely unexpected properties, about as weird as it gets.
One of the oddest substances disobeys all the usual rules by becoming less prone to shattering as it cools rather than more so. The high-entropy alloy of iron, manganese, nickel, cobalt and chromium gets less and less brittle as it cools, right down to minus 200 degrees Centigrade. And it has already caught the eye of the nuclear fusion research community, who need superconducting electromagnets that don’t break when extremely cold and, if they do break, don’t do so catastrophically.
Corrosion resistance is one of the next properties scientists are preparing to test. Some are busy hunting for alloys that can raise the operating temperature of jet engines to achieve better fuel efficiency, examining a cluster of elements called refractory metals with unusually high melting points of 2500C or more. Others have created high entropy versions of bronze and brass, substituting the copper the traditional alloys include with nickel, manganese, zinc and aluminium to make super wear-resistant brass parts for vehicles and other machines.
What does the future hold? The new alloy scene is so extraordinary and unpredictable that it’s hard to say. But one thing is certain: as metal suppliers of things like aluminium products, brass sheet, stainless steel and more, we’re living in very exciting times.
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