Disordering and amorphization of L12-type alloys by mechanical attrition

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Abstract
X-ray diffraction patterns obtained during the grinding of Ni3Ge and Ni3Al alloys which at equilibrium exhibit the L12 ordered fcc structures show the emergence of a nanocrystalline structure and transformation to the disordered fcc form but little amorphization. Furthermore, the non-L12 Al2Pt alloy which also has a more strongly negative heat of mixing is easier to amorphize than the Ni3Ge and Ni3Al with L12 superstructure. This is in contrast to the Zr3Al compound (also L12-type) for which a short milling time is sufficient for obtaining complete amorphization. Variations in the aptitudes toward amorphization of the three L12-type alloys under ball-milling conditions are attributed in part to the differences in the lattice stability terms of their disordered fcc phases.