Effect of glass short-range order on crystallization onset in Al–Y–Ni glasses

Effect of substitution of rare earth by mischmetal on the devitrification process of Al–X–Ni–Co (X=Y, Ce, Mm) alloys

“…Although the crystallization products after the first transformation stage are so different between the Y alloy and the other two alloys, activation energy for the Y alloy is only slightly lower than that in the case of the Ce and Mm alloys (2.5 eV and 2.8-2.9 eV, respectively). Similar values of E a have been observed for Al 85 (NiY) 15 series of alloys for the primary crystallization ($3 eV) [15], although lower values were found for the primary crystallization of Albased alloys with low RE content, 3 at.% ($1.5 eV) [16]. At the last crystallization stage (which yields to the stable phases Al 11 Mm 3 , Al 11 Ce 3 and Al 3 Y for the Mm, Ce and Y alloys, respectively) E a is very similar in all the studied cases ($1.7 eV).…”

Influence of Gd and Fe on crystallization of Al87Y5Ni8 amorphous alloy

“…The latter phase decomposes into two phases -fcc Al and an unidentified intermetallic compound with a primitive cubic structure. An increase of Y content in Al-RE-TM alloy from 5 to 10 at.% leads to an increase of the temperature of primary crystallization from 508 to 565.5 K. These data [5] are in some disagreement with the data of Gogebakan and Uzun [6] who also investigated crystallization of Al 85 Y x Ni 15Àx (x = 5, 10) glasses. According to their data the primary crystallization temperatures are lower and vary from 503 (for x = 5) to 525 K (for x = 10).…”

“…A series of Al 85 Y x Ni 15Àx (x = 5, 7, 8, 10) glasses have been investigated by Saini et al [5]. The three-step crystallization behavior has been found for x = 5 and 7, while for those with x = 8 and 10 the crystallization occurs in four steps.…”

Structure relaxation and crystallization of Al83Ni10Ce7 metallic glass

“…The change of the second peak suggests that the amorphous structure unit of the second peak is influenced by the pre-annealing temperatures. Structure relaxation, which allows atoms rearrangements in the amorphous matrix to get better atomic packing degree, can reduce the free-volume (quenchedin defect concentration) and retard the mobility of atoms [5,14]. Here, we assume that the embryo clusters of nuclei become more stable, because of local atoms rearrangement, to favorably initiate the second stage crystallization during isothermal annealing below 533 K. As a reflection, the second peak gradually overlaps with the first peaks with increasing pre-annealing temperature.…”