Detection of Phase Transition in Free-Cutting Al-Mg-Si Alloys by Resonant Ultrasound Spectroscopy


Article Preview

The transition temperatures of small amounts of eutectic particles contained in free-cutting aluminum alloys (namely AA6262 and AA6023) are investigated in this paper. Detection of the transition temperatures by conventional differential scanning calorimetry (DSC) measurements is difficult because of the small volume fraction (~ 1wt.%) of the eutectic. On the other hand, the melting of the particles induces small changes of elastic moduli of the alloy, which can be sensitively measured by resonant acoustic methods, for example by resonant ultrasound spectroscopy (RUS). It is shown that the phase transitions of the particles correspond to well-detectable changes of the resonant spectrum, which enables a more detailed characterization of the transition process. A significant thermal hysteresis is observed between the cooling and the heating runs, and also the widths of the temperature ranges in which the transitions occur exhibit a strong melting/freezing asymmetry.



Materials Science Forum (Volumes 794-796)

Edited by:

Knut Marthinsen, Bjørn Holmedal and Yanjun Li




J. Nejezchlebová et al., "Detection of Phase Transition in Free-Cutting Al-Mg-Si Alloys by Resonant Ultrasound Spectroscopy", Materials Science Forum, Vols. 794-796, pp. 21-26, 2014

Online since:

June 2014




* - Corresponding Author

[1] E.M. Elgallad, F.H. Samuel, A.M. Samuel, H.W. Doty, Machinability aspects of new Al-Cu alloys intended for automotive castings, Journal of Materials Processing Technology 210 (2010) 1754-1766.


[2] J. Faltus, M. Karlík, P. Haušild: Properties of free-machining aluminum alloys at elevated temperatures In: Proc. ICAA13, Pittsburgh, PA, John Wiley & Sons, Inc., Hoboken, NJ, USA, 2012, 873-878.


[3] R.G. Leisure, F.A. Willis, Resonant ultrasound spectroscopy, J. Phys.: Condens. Matter 9 (1997) 6001-6029.

[4] J. Nejezchlebová, Measuring the temperature dependence of resonant ultrasound spectra of alloys Al-Mg-Si with additions of low melting point metals, Research project, CTU in Prague, Department of materials (2012) (in Czech).

[5] R. Truell, C. Elbaum, B.B. Chick, Ultrasonic Methods in Solid State Physics, first ed., Academic Press, New York, (1969).

[6] H. Seiner, L. Bodnárová, P. Sedlák, M. Janeček, O. Srba, R. Král, M. Landa, Application of ultrasonic methods to determine elastic anisotropy of polycrystalline copper processed by equal-channel angular pressing, Acta Materialia 58 (2010) 235-247.