Foaming metal

Reseachers at the materials science laboratory at Caltech in the US have come up with a new type of liquid metal foam.

Reseachers at the materials science laboratory at Caltech have come up with a new type of liquid metal foam.

According to Chris Veazey, who is working on his doctorate in materials science, the new material is a bulk metallic glass that has the stiffness of metal but the springiness of a trampoline. ‘You can squish it and the metal will spring back,’ says Veazey, who has given the material the tentative name ‘Bubbloy,’ a combination of ‘bubble’ and ‘alloy.’

Greg Welsh, the co-inventor and also a doctoral student in materials science at Caltech, adds that Bubbloy is made possible by a process that foams the alloy so that tiny bubbles form. Preliminary results show that if the bubbles nearly touch, the substance will be especially springy.

‘We think it might be especially useful for the crumple zone of a car,’ says Veazey. ‘It should make a car safer than one where the structures in the crumple zone are made of conventional metals.’

Bubbloy is made of palladium, nickel, copper, and phosphorus. This particular alloy was already known as one of the best bulk metallic glasses around, but Veazey and Welsh’s contribution was figuring out how to get the stuff to foam.

Veazey and Welsh’s preliminary castings result in Bubbloy that is light enough to float in water, yet quite strong and elastic.

Other researchers have previously figured out how to foam metals like titanium and aluminium, but Bubbloy is claimed to have big advantages in the strength-to-weight ratio.

Researchers at the UK’s NPL have studied the properties of metal foams for some years. Indeed, a good description of the foams that are available today and the manufacturers of them can be found on the NPL web page by clicking <a href=’’>here</a>.

And for designers who are interested in comparing the properties of commercially available foams with other materials, UK-based Granta Design have produced a software tool called the Cambridge Engineering Selector with a metal foams database that currently contains material, mechanical, thermal and other properties for 130 aluminium, nickel and copper foams. You can check that out, by clicking <a href=’’>here</a>.

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