A giant leap on the fundamental phenomenon of age-hardening in aluminium alloys!

SIZE DEPENDENT AGE-HARDENING DISCOVERED! 

The Montanuniversitaet Leoben has a small breakthrough to report. The age-hardening of metals was discovered at the beginning of the twentieth century. 110 years later, Phillip Dumitraschkewitz was able to show in his doctoral thesis under supervision of Professor Pogatscher from the Chair of Nonferrous Metallurgy, that the effect depends on the material dimensions. Together with colleagues from ETH Zurich, the researchers published their findings in the renowned journal “Nature Communications”.

After rapid quenching of special alloys, dissolved atoms arrange themselves into nanometer-sized clusters via minute movements. These clusters significantly change the material properties, especially for aluminum or magnesium. Today, the effect is the basis for a variety of strong metal alloys in automobiles, aerospace or electronic devices.

The researchers from the Montanuniversitaet Leoben were able to study the hardening of an aluminium alloy at the atomic level by means of a new measurement method, cryo-atom probe tomography, and show that cluster formation is size-dependent. Fundamentally important is the finding, that the diffusional process stops when the sample size changes from the micrometer to the nanometer range, independent of the used metal. In addition to the directly recognizable significance for ever-smaller components or within the structure of modern alloys, the newly discovered effect is also significant in today’s frequently used high-resolution microscopy. In this area, small sample dimensions are generally small, but such size effect has not been taken into account so far. The researchers now hopes to significantly reduce the inconsistencies in the field of early clustering in alloys that has been encountered over the past two decades.

Detailed information on the publication: P. Dumitraschkewitz, P.J. Uggowitzer, S.S.A. Gerstl, J.F. Löffler, S. Pogatscher. (2019). Size-dependent diffusion control of natural aging in aluminum alloys. Nature Communications, https://doi.org/10.1038/s41467-019-12762-w