Jun
2
New Super-Strong, Super-Tough Alloy
“No other conventional material is this robust.” — Tibi Puiu, ZME Science
Materials scientists are always experimenting with metal alloys in order to improve one or more properties. For example, add a little (~1%) carbon to a lot of iron and you get steel, which (among other things) is stronger than iron alone. The resulting alloy can then have many uses and lead to new inventions that do things not previously doable.
When it comes to high-performance jet and rocket engines,
“…the operating temperature is limited by the structural materials which must withstand it…. We have exhausted the ability to further optimize the materials we currently use at high temperatures, and there’s a big need for novel metallic materials.”
This dilemma, as explained by PhD student David Cook, led to Cook and his team at the Lawrence Berkeley National Laboratory developing a new alloy that opens up new vistas.
In short, they mixed 45% niobium, 25% tantalum, 15% titanium, and 15% hafnium, resulting in… well, I don’t think it has a name, yet. (My vote is for “infrangium”, or maybe simply “NTTH” or “Cook’s metal”.) But, they tested this new alloy under temperatures ranging from -196°C and 1200°C, and not only did it remain extremely strong, but it resisted fracturing throughout.
Four-dimensional scanning transmission electron microscopy (4D-STEM) revealed that the feature responsible for the unusual fracture-resistance is called “kink bands” — i.e., “abrupt bends in the crystal lattice that occur under stress.” These normally cause a material to weaken and crack more. This time, however, the kink bands serve to distribute the stress, thereby greatly lessening the cracking that leads to fracturing. The result: “extraordinarily high fracture toughness”.
Further research and testing is needed, of course, before the alloy can be used in commercial applications — e.g., jet turbine engines or spacecraft components like a rocket booster’s nozzle. But, things look good… not to mention “kinky”. (Sorry.)
