Crystallization of Amorphous Alloys by High Energy Mechanical Defofmation

Abstract

Resume -Le broyage B billes B haute energie a et6 utilise frequemment ces dernieres annees pour produire des alliages amorphes en alliant mecaniquement des elements pures cristallins ou en deformant mecaniquement des composes intermetallics. Le processus de broyage B billes est normallement caracteris6 par une temperature effective locale au site d'impact qui controle les transformations de structure survenant lors du broyage. A des intensites de broyage Blevees, la temperature effective serait telle que la precipitation de composes intermetalliques pourrait survenir/l. Dans cette publication, le processus de broyage B bille est utilise pour cristalliser des alliages B base de £er dQjA amorphes. Nous comparons la stabilite structurale des alliages amorphes lors d'un processus thermique et lors de deformations mecaniques et les resultats indiquent que la temperature effective locale au site de la collision n'est pas le param&tre important qui controle le processus de cristallization durant les deformations.

Calorimetric and microstructural analysis of deformation induced crystallization reactions in amorphous Al88Y7Fe5 alloy

“…For Al based amorphous alloys, nanocrystals have first been deformation induced in shear bands of bent ribbons [4], but they have also been detected for ball-milled [5], cold rolled [6], and high pressure torsion strained samples [7]. Attempts to rationalize the deformation induced crystallization reactions have focused on two approaches.…”

Ion irradiation induced nanocrystal formation in amorphous Zr55Cu30Al10Ni5 alloy

“…However, MGs will develop ordered structures if enough energy is supplied. Numerous studies have shown that nanocrystals can be formed under annealing [8], deformation [9], bending [10], nanoindentation [11] and ion or electron irradiation [12][13][14][15][16]. Although the specific mechanisms that induce partial crystallization are different in each of these cases, the general crystallization phenomena are typically associated with enhanced atomic mobility.…”

Deformation-driven catalysis of nanocrystallization in amorphous Al alloys

“…Examples of deformation-induced crystallization reactions include Fe-based amorphous alloys [12–16], amorphous Ni–P alloy [17], bulk amorphous Zr and Cu–Zr alloys, and amorphous Al alloys [18–22]. The deformation techniques used so far include bending [23], ball milling [14–16 24], cold rolling [12,25–32], high-pressure torsion straining [18,33], nanoindentation [34], and uniaxial compression [35]. The results of intense deformation have demonstrated nanocrystals with number densities of up to 10 22 m −3 and average sizes of less than 10 nm, but the origin of the deformation-driven nanocrystallization remains an area of active research.…”