The quasi-cristals, formerly considered impossible, are now found in aluminum alloys printed in 3D and have increased their strength.
When the research engineer on materials Andrew IAMS observed a new aluminum alloy sheet using an electron microscope, he discovered an abnormal atomic arrangement phenomenon – the atomic arrangement of the aluminum alloy is extremely irregular, completely different from the repeated structure typical of most crystals. “I started to get excited at that time,” recalls Eames, “because I realized that I could have discovered the quasi-cristal.”
This instinct was finally confirmed, and Eames and colleagues of Nist confirmed that there was a quassecristal in this aluminum alloy, a rare atomic structure which differs from traditional crystals in that its atomic arrangement model is not repeated. Even more surprising, the study has also shown that the presence of quasscristals can considerably increase the strength of aluminum alloys. Related search results have been published in the Journal of Alloys and Compounds.
This aluminum alloy is formed in extreme 3D metal printing conditions. This discovery can help develop new aluminum alloys that specifically use the properties of quasi-cristals to improve the resistance of the material.
NIST researchers emphasize that non-repetitive quasi-cristals can cause aluminum defects printed in 3D, thus increasing the strength of the metal. The Penrose tile pattern has properties similar to quasi-cristals. Although these models are made up of several identical basic forms, the global models are not repeated.
The quasi-cristals are different from ordinary crystals, which have repeated atomic arrangement models, such as salt crystals in the shape of a cube. The quasi-cristal fills the space, but its atomic arrangement is never repeated. The discovery of the quasi-cristals dates back to the 1980s and was discovered for the first time at the NIST by Dan Shechtman. Although this discovery was initially questioned, it was finally confirmed and won the Nobel Prize in 2011.
Decades later, while working in the same mechanism, Eames again discovered quasi-cristals in aluminum alloys printed in 3D.
As we all know, the 3D impression of aluminum has always been a huge challenge. “High resistance aluminum alloys are almost impossible to print,” said the fan of the physicist Nist Zhang. “Because they are subject to cracks during printing, which makes them unusable.” The aluminum fusion point is generally around 700 ° C, but during 3D printing, aluminum should be heated to extremely high temperatures beyond its boiling point (2470 ° C), which will change the performance of aluminum.
To overcome this challenge, in 2017, HRL Laboratory and researchers from the University of California, Santa Barbara has jointly developed a reinforced aluminum alloy of Zirconium which can effectively avoid cracking during 3D printing. The NIST then conducted a detailed study of this aluminum-zirconium alloy to better understand its atomic structure.
Professor Zhang said: “To ensure that this new metal can be applied to key components such as military aircraft, we must have a more complete understanding of the interactions between atoms.” Thanks to research, the NIST team finally noted that the quasisicristals play a crucial role in aluminum alloys, improving the strength of the alloy.
Research results show that quasi-cristals can not only increase the strength of aluminum alloys, but also open up new possibilities for the future design of alloys. Professor Zhang added: “We have shown that quasi-cristals can effectively improve the strength of aluminum alloys, and future researchers can try to intentionally introduce quasi-cristals into new alloys to further improve their performance.”
