The first 3D printed nanostructured high-entropy alloy was introduced
Scientists from the University of Massachusetts Amherst and Georgia Tech published a paper in the latest issue of the journal Nature online that they used 3D printing methods to produce a duplex nanostructured high-entropy alloy (HEA), which is superior in strength and ductility to other existing advanced 3D printing materials, and is expected to give rise to high-performance parts that can be used in aerospace, medicine, energy and transportation.
Over the past 15 years, HEAs have grown in popularity. HEA is an alloy made of 5 or more metals of equal or approximately equal amount, and has many desirable properties, so it is highly valued in the field of materials science and engineering. 3D printing technology is currently used in the field of material development, and laser-based 3D printing can produce large temperature gradients and high cooling rates, which is difficult to do with traditional methods.
This time, the researchers combined HEA with advanced 3D printing technology, laser powder bed melting, to develop new materials with unprecedented properties. Because the process melts and solidifies the material very quickly, the microstructure of the obtained material is very different from the material produced by traditional methods. The microstructure of the new material looks like a network structure, consisting of alternating nanolayered structures called face-centered cubic (FCC) and body-centered cubic (BCC), which are embedded in microscale eutectic clusters, and the hierarchical nanostructure HEA enables the two phases to deform together.
The researchers said that the atomic rearrangement of this unusual microstructure gives it ultra-high strength and higher ductility, and compared with traditional metal castings, the strength of the new material is increased by 3 times, and the ductility is not reduced but increased. Giving HEA toughness and ductility helps to develop lightweight structures that are mechanically efficient and energy-efficient.
The research team also developed a computational model of biphasic crystal plasticity to understand what FCC and BCC nanosheet layers play and how they work together to increase the strength and ductility of the material. The results show that the BCC nanosheet layer has extremely strong properties, which is essential to achieve the excellent strength-ductility synergy of the alloy. In the future, scientists are expected to use 3D printing technology and HEA to develop high-performance components that can be widely used in biomedical, aerospace and other fields.