Developing metals with stronger properties is by no means something new; material scientists have been tweaking metals at a microscopic level for decades by mixing or joining two or more different metals together to develop new materials that are much stronger. The techniques they used however, have often resulted in weakening their microstructures especially around the weld point between the different metals, which many times ruined the whole purpose of the new material altogether.
But things seem to be changing, as a team from Ohio State University managed to develop a new welding technique called Vaporized Foil Actuator (VFA) welding. This new method is actually quite simple: a short electrical pulse is passed through a thin piece of Aluminum foil, which vaporizes within microseconds, generating a burst of hot gas which pushes the two pieces of metal together at speeds up to thousands of miles per hour.
What makes VFA welding special
What’s astonishing about this method is that it consumes 80% less energy than common welding techniques, yet creates bonds that are 50% stronger.
Another common welding technique called Resistance Spot Welding, involves passing high electric currents through pieces of metal, forcing the metals’ natural electrical resistance to generate heat that partially melts them together to form the weld. This technique has significant drawbacks however, as generating high currents consumes a lot of energy, and the melted portions of metal are never as strong as they were before.
With VFA welding however, the pieces of metal don’t melt, so there are no areas of weakened interfaces between them. Instead, the process directly bonds the atoms of one metal to the other. This technique also uses less energy, as the electric pulse is very short, and the energy required to vaporize the foil is significantly less that that required to melt the metal parts.
When viewing the bonds under a high-powered microscope, the bonds were found to actually be very beautiful, featuring wave-like patterns created as the atoms of both metals wrap around each other.
Microscope view of Copper (top) welded to Titanium (bottom) using new VFA welding technique (photo credit: Ohio State University)
So far, the engineers managed to successfully bond different combinations of Copper, Aluminum, Magnesium, Iron, Nickel, and Titanium. They also created strong bonds between commercial steel and Aluminum alloys, something which was impossible before now (not only that, but the weld regions are actually stronger than the base metals).
Why this is great news
VFA welding is powerful enough to shape metal parts and at the same time weld them together, thus saving manufacturers a big step.
This new technique opens a huge door of possibilities to the automotive industry, which was forced to make do with combining traditional heavy steel parts with lighter, alternative metals to reduce vehicle weight. Now they have a whole new range of options when it comes to developing stronger, lighter materials for their parts using less energy.