Minsu Jung

Effect of Heating Rate on the Activation Energy for Crystallization of Amorphous Ge2Sb2Te5 Thin Film

The crystallization of the amorphous Ge 2 Sb 2 Te 5 film was investigated by in situ electrical sheet resistance measurement. The crystallization start temperature increases logarithmically with heating rate and is equated. The effective activation energy E A of the crystallization is 2.34 eV at slow heating rates below 40°C/min and decreases to 0.49 eV at higher heating rates because of the reduced activation energies for both nucleation and growth of the crystalline face-centered cubic phase by overheating at high heating rates.

Néel temperature of high Mn austenitic steels

The predictive equations for the Néel temperature (TN) of high Mn austenitic steels were reviewed and reevaluated using 116 different measured TN values. The previous equations gave good predictions for TN values of high Mn-low C austenitic steels, but not for those of medium and low Mn-high C austenitic steels, including TWIP steels with less than 20 at.% Mn. Therefore, an improved TN equation for medium and low Mn-high C as well as high Mn-low C was newly suggested. To improve the accuracy of the new equation, especially for high C TWIP steels, the TN values of three different high C TWIP steels were experimentally measured using a superconducting quantum interference device (SQUID) because there are few measured TN values of high C TWIP steels in the literature.