Pelting metals under high temperatures has revealed that some get even stronger when heated, which could help improve 3D printing and certain industrial processes
By Karmela Padavic-Callaghan
22 May 2024
A crater formed by a laser in the metal titanium
Science Photo Library / Alamy
Heating metals can sometimes make them stronger, despite the common conception that higher temperatures just make them pliable. This surprising phenomenon could lead to a better understanding of important industrial processes and make for tougher aircraft.
“It was just so unexpected or backwards of what you might conventionally see,” says Ian Dowding at the Massachusetts Institute of Technology. Together with Christopher Schuh at Northwestern University in Illinois, he uncovered the odd effect by bombarding metals with tiny projectiles.
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The researchers used a laser to launch microscopic aluminium oxide particles towards heated samples of the metals copper, gold and titanium at velocities of thousands of kilometres per hour.
A high-speed camera recorded the impact and rebound of these tiny projectiles as they hit each metal sample, a process illuminated by another laser. Based on the particles’ trajectories and the size of the craters they left on the metals, Dowding and Schuh calculated the strength of each metal and determined how it changed at rising temperatures.
The copper grew roughly 30 per cent stronger after the team increased its temperature by 157°C. Most strikingly, at 177°C (350°F) this typically soft material proved as sturdy as some types of steel.