Yuji Ikeda

Metal is like a rope made of many strands: pull too hard and it snaps. Engineers have long sought a way to make it both strong and flexible at the same time. Typically, additives that increase strength make the metal brittle. But a team of materials scientists found a loophole: they added a small amount of nitrogen to the CrMnFeCoNi alloy, just one atom in a hundred, and got an unexpected result.

Hydrogen is the lightest gas, but it has a knack for sneaking into metals. If you pump hydrogen into a steel cylinder at high pressure, some atoms will squeeze between the metal atoms. The metal can become as brittle as a stale cracker. But you can also turn this property on its head — store hydrogen inside a metal sponge.