Mordecai's favorite alloys

There are some spectacular results from centuries of material science and metallurgy. One of the spectacular things about metals in particular is the incredibly complicated interactions and the sometimes non-intuitive results that come from mixing metals.

In fact, it's not even just what's in the mix... but what happened to it, and even how fast it happened. Metallurgy is like baking, but more complicated. The fact is that there are large amounts of information that help to understand some parts of metallurgy, but there is NO way to accurately predict a lot of the properties for an untested alloy.

Even in simple two-metal systems, say nickel and iron, there's a lot of surprises. For instance, Invar, a 36% nickel 64% iron alloy which has the unique property of extremely low thermal expansion (less than 1.3 x10^-6 1/K). Pure iron's thermal expansion coefficient is about 12*10^-6, and pure nickel's is about 13. But put them together in the right ratio, and you get 1/10th of that!

Another favorite is Monel; I remember what's in Monel because it reminds me of money... and in monel is copper (pennies) and nickel (nickels, duh!). Monel sold industrially usually includes some other trace materials as well. Monel is stronger than either copper or nickel are by themselves. It also exhibits exceptional corrosion resistance.

And, one more cool alloy is Nitanol, a nickel-titanium alloy that is both super-elastic (you can bend it like crazy and it will spring back unharmed) as well as a shape-memory alloy (you can heat it up and under special circumstances it will change shape).

And the last favorite alloy is finally one that has no nickel in it at all... it's a eutectic alloy of Gallium, indium and tin called Galistan. Just like the copper-nickel alloy was stronger than either copper or nickel, a eutectic alloy melts at a temperature lower than either of the things its made of. Galistan freezes at -19 C (-2.2 F), so it's liquid even colder than water! Remarkably, pure gallium has a melting point of 29C (85 F), and so will melt in your hand. Also remarkably, pure gallium expands 3 percent upon freezing; like ice, solid gallium is less dense than liquid gallium. If you're interested in more boiling water level of melting (melting tea spoon, for instance), then you want Fields metal or Wood's metal. You can buy both gallium and Field's metal here: http://www.scitoyscatalog.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=SC&Category_Code=H