Crystallization Behavior of Thermally Rejuvenated Zr₅₀Cu₄₀Al₁₀ Metallic Glass

Abstract

The recovery annealing technique was used to clarify the crystallization behavior of a rejuvenated Zr 50 Cu 40 Al 10 metallic glass. Speci c heat and thermal expansion measurements showed that the glassy states of fast cooled and recovery annealed samples are almost identical from the energetic and volumetric points of view. Dynamic mechanical analysis also suggested that their internal microstructures resemble each other. These results indicate that the glassy state and the structure can be controlled according to the nal cooling conditions from the supercooled liquid region. However, a clear difference of the incubation time for crystallization was observed between the fast cooled and recovery annealed samples, implying that thermal accumulation seems to mostly correlate to the crystallization rather than to atomic diffusion through the newly created excess free volume in the rejuvenated sample. In addition, a transmission electron microscopy image of the sample, performed on double sets of the recovery annealing process, shows a precipitation of the crystalline phase with approximately 50 nm in diameter in the amorphous matrix. These results suggest that the recovery annealing independently leads to two different thermal paths, one towards structural rejuvenation and the other towards crystallization. The high-resolution transmission electron microscopy result of the recovery annealed sample indicates that these two regions co-exist in the amorphous matrix.

Unveiling a new type of ultradense anomalous metallic glass with improved strength and ductility through a high-pressure heat treatment

“…For the relaxed sample, T g was determined to be 701 K, which was almost the same as that of the as-cast state, whereas T x was slightly lower (781 K). During the annealing process, thermal accumulation (i.e., atomic ordering) may have occurred in the system [14][15][16] , resulting in the reduced crystallization temperature. Notably, for the high-pressure heat-treated sample, the glass transition temperature was almost the same (T g = 703 K), whereas the crystallization temperature (T x = 749 K) was lower than that of the as-cast state by 37 K. In addition, the wide plateau region observed above T g in the as-cast and relaxed samples, which is considered to be a supercooled liquid state 17 , clearly diminished in the high-pressure heat-treated sample.…”

Temperature Dependence of Nanoindentation-Induced Deformation Dynamics in Zr-Based Bulk Metallic Glass

“…This estimate is consistent with previous experimental evaluations of alloys with the same composition, with T g = 706 K (433°C) and T x = 792 K (519°C). [24][25][26] Hence, crystallization processes might affect the hardness values measured at 500°C.…”

Various Rejuvenation Behaviors of Zr-Based Metallic Glass by Cryogenic Cycling Treatment with Different Casting Temperatures

“…Previous study has shown that the nano-clusters may be B2-CuZr phase [22]. The thermal expansion coefficients for the amorphous and crystalline phases have been reported to be ~ 1.3 × 10 −5 K −1 and 1.14 × 10 −5 K −1 , respectively [26], E c and E a have been reported to be ~ 77 and 123 GPa, respectively [27], and ν c and ν a have been reported to be ~ 0.385 and 0.383, respectively [28, 29]. ΔT was ~ 180 K (293 K to 113 K).…”