Investigation of crystallization behavior of Hf26Be18Ti18Zr18Cu7.5Ni12.5 high mixing entropy amorphous alloys

In this paper, the crystallization kinetics of Hf26Be18Ti18Zr18Cu7.5Ni12.5 high mixing entropy amorphous alloys under non-isothermal conditions are studied. The alloy shows two different crystallization events. In addition, the activation energies of the two crystallization events are calculated using the Kissinger, Augis-Bennett, and Ozawa methodologies. Similar values are obtained by the three equations. The activation energy of the first crystallization event is slightly less than that of the second crystallization events, which indicates that the first crystallization can easily occur. The modified Johnson-Mehl-Avrami (JMA) equation is then used to further analyze the non-isothermal crystallization kinetics. The Avrami exponent (n(alpha)) is between 1.5 and 2.5 for the first crystallization even and most instances (0.1 < alpha < 0.5) of the second crystallization event, which demonstrates that the crystallization mechanism has mainly been controlled by a three-dimensional growth with a nucleation rate decrease. Moreover, n(alpha) is between 1 and 1.5 in the second stage of the second crystallization event (0.5 < alpha < 0.9), which implies a direct growth of crystal nuclei. Compared with the other alloys, Hf26Be18Ti18Zr18Cu7.5Ni12.5 has stronger high entropy effect, leading to more sluggish diffusion and more difficult crystallization.