Abstract:The gradual nanocrystallization and amorphization mechanisms in various Zr-X alloys during accumulative roll bonding (ARB) are explored. The effects of strain accumulation, the relative initial hardness of the elemental foils, the enhanced diffusion, and the critical nano size for the sudden transformation from the nanocrystalline phase to the amorphous state are examined. For elemental foils with compatible initial hardness, the nanocrystallization and amorphization rates appear to be higher. The estimated di… Show more
“…Within the last two decades, on the other hand, various severe plastic deformation (SPD) processes for achieving grain refinement have been developed [7][8][9]. It was also found that SPD technique can be used to fabricate non-equilibrium alloys or even amorphous alloys [10,11]. High pressure torsion (HPT) is a kind of these SPD techniques.…”
“…Within the last two decades, on the other hand, various severe plastic deformation (SPD) processes for achieving grain refinement have been developed [7][8][9]. It was also found that SPD technique can be used to fabricate non-equilibrium alloys or even amorphous alloys [10,11]. High pressure torsion (HPT) is a kind of these SPD techniques.…”
“…Future simulation can be conducted for one pureelement nanocrystalline phase in conjunction with fully mixed amorphous matrix, as for the experimentally observed situation. It is expected that the ARB cycles needed to complete the mixing and vitrification may be further reduced to around three cycles, as observed previously in the Zr-Ti system [7,8].…”
Section: Simulated Microstructure Evolution During Arbmentioning
confidence: 66%
“…The nanocrystalline phase near the interface is around 2 nm with nearly sphere in shape and it seems to become unstable when the size is further refined to below 2 nm. Previous studies [6,8] have concluded that the pronounced increase in interfacial energy of the nanocrystalline phase lead to the transformation into the amorphous state, and interdiffusion across the phase boundary is the controlling atomic mechanism [14], as depicted in Fig. 1(b).…”
Section: Transformation Between Nanocrystalline and Amorphous Phasementioning
confidence: 95%
“…According to our previous reports [6][7][8] on the Zr base alloys made by ARB route, the grain size of ARB specimen was gradually refined to only a few nanometers while the amorphous volume fraction also increased with increasing repeated roll-bonding process. Once the nanocrystalline phases measuring a few nanometers are formed in the amorphous matrix, a fully amorphous state seems to rapidly complete after a few roll bonding cycles.…”
Section: Introductionmentioning
confidence: 93%
“…The grain size of the Zr-Ni system is refined from the original w100 mm down to w500 nm and finally to w2 nm with increasing ARB cycles, as partly presented in our previous papers [6][7][8]. It is considered that the grain size refinement arose from the strain-induced dislocation activity and shear band propagation during the initial and intermediate stages of ARB.…”
Section: Transformation Between Nanocrystalline and Amorphous Phasementioning
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