In recent decades, scientists have created ever-stronger metals — but the techniques used to weld them often ruin the materials' molecular properties. Now, a team has developed a way to weld together these previously un-weldable materials.
Many metals have been tweaked by material scientists at the microscopic level to be much, much stronger. But their intricate new microstructures are ruined, in part at least, by the high temperatures used to weld them, decreasing their strength around the weld.
Now, a team from Ohio State University has developed a new welding technique called vaporised foil actuator (VFA) welding. It’s fairly straightforward: a short electrical pulse is passed through a piece of thin aluminium foil. The foil vaporises within microseconds, creating a burst of hot gas which pushes two pieces of metal together at speeds of up to thousands of miles per hour.
The metals never melt; instead, the impact is strong enough for the atoms of one metal to bond with the atoms of the other. The result, viewed under a microscope, is wave-like pattern created as the microstructures of the metals wrap around each other. The technique was recently presented at the Materials Science & Technology 2015 meeting.
The technique actually uses less energy than most welding techniques, but more importantly it preserves the properties of the high-strength metals around the weld, increasing the strength of a join by up to 50 per cent. So far, the team has used it to fuse together different combinations of copper, aluminium, magnesium, iron, nickel and titanium.
The method will prove attractive to engineers keen to use the latest high-strength materials, which will in turn allow them to turn shave weight from the airplane, car, or whatever else it is they’re building. [Ohio State University]