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How to Weld Together Un-Weldable Metals

Many metals have been modified at the microscopic level to be much, much stronger. But the heat from traditional welding methods breaks down the intricate microstructures of these metals, weakening them. Now, engineers at The Ohio State University have developed a new welding technique that uses 80% less energy than spot welding while creating bonds that are 50% stronger.
In spot welding, contacting metal surfaces are partially melted and joined together by the heat generated from resistance to electric current (our induction furnace works using similar principles). Unfortunately, generating the necessary current requires lots of energy, and the melted portions of the metal lose strength in the process. The new technique, dubbed vaporized foil actuator (VFA) welding, bypasses both of these problems.

In VFA welding, a short electric pulse is delivered to a thin piece of aluminum foil. Within microseconds, the foil vaporizes in a burst of hot gas. The reaction is like a miniature explosion that pushes two pieces of metal together at speeds approaching thousands of miles per hour. The impact is so powerful that the atoms of one metal bond with the atoms of the other.

The electric pulse in VFA welding is less than what would be required to melt the metal parts in spot welding. And since the metal is never melted, its atomic structure – and strength – is preserved. So far, engineers have used VFA welding to successfully bond different combinations of copper, aluminum, magnesium, iron, nickel and titanium. They also bound commercial steel and aluminum alloys – an impossible feat with traditional welding. As the technology develops, we are sure to hear about more combinations.

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