Scientists create light, super-strong gold by puncturing holes in it

Chinese scientists have unveiled a novel method to produce pure gold that combines lightweight properties with remarkable strength. 

This innovative approach, developed by researchers at the Shenyang National Laboratory for Materials Science, involves forming uniformly small pores within the solid metal. 

The implications of this research could significantly impact the aerospace, automotive, and consumer electronics industries, where there is a pressing need for materials that are both strong and lightweight.

The science behind the innovation

Traditionally, metal forming techniques such as casting, welding, and 3D printing are designed to eliminate internal bubbles in metals, as these are typically considered significant material flaws. 

Engineers have historically taken great care to avoid these voids due to their detrimental effects. Internal bubbles can compromise metal strength, reduce durability at junctions, and impair surface finish.

However, the research team led by Jin Haijun at the Chinese Academy of Sciences (CAS) has shifted this perspective. Instead of removing these voids, they have refined their size and regulated their shape and distribution.

The researchers discovered that this approach mitigates the negative effects of bubbles and can also offer unexpected benefits.

“This suggests an attractive way to manipulate the properties of solids,” said Brent Grocholski, a senior editor at Science, as reported by South China Morning Post.

The research highlights how the traditional view of bubbles as flaws can be reconsidered to unlock new material capabilities.

Significant strength gains with nanopores

The team used gold as a model material to develop their technique, creating uniformly structured porous gold through a de-alloying corrosion process. By compressing and then annealing the metal—heating and cooling—the researchers generated a new material with dispersed nanopores smaller than 100 nanometers.

Tests revealed that adding nanopores at a volume fraction of 5 to 10 percent resulted in a 50 to 100 percent increase in the strength of the gold. This enhanced material can bear higher loads while maintaining good plasticity. In some instances, the plasticity even surpassed that of fully dense gold of the same size.

“This improvement is due to the dispersed nanopores helping to alleviate stress and strain concentration around the voids, thereby inhibiting the initiation of cracks,” Jin Haijun explained.

“The material’s large specific surface area facilitates interactions between the surface and dislocations, which enhances strength and strain hardening rates, the latter contributing to improved plasticity,” Jin added. The strategic placement of these nanopores helps in balancing the material’s strength and ductility.

Environmental and industrial implications

The subtractive approach stands in contrast to traditional methods that enhance strength by adding lighter alloy elements like aluminum or lithium. The new method offers an environmentally friendly and cost-effective strategy to enhance metal without additional weight or pollution. The dispersed nanovoids reduce the density of pure gold by more than 10 percent, contributing to its lightness and recyclability.

This innovative approach also preserves essential physical and chemical properties of the gold, including its thermal and electrical conductivity and corrosion resistance.

“For instance, gold with nanovoids can be utilized as connector or contact materials in electronics,” Jin noted.

“This strengthening strategy might also be applied to other metals and engineering alloys as long as the nanovoids can be effectively integrated into the material, with potential applications across multiple fields,” Jin concluded.

The results were published in the journal Science.