The microstructural evolution during mechanical alloying of Ti and Al powders has been investigated by X-ray diffraction, scanning electron microscopy (SEM)-energy dispersive spectroscopy, and transmission electron microscopy (TEM). Observations by SEM showed a progressive change of the powders' morphology as a function of milling time. Observations by TEM, performed on a sample milled for 20 h, revealed the simultaneous occurrence of amorphous zones and nanocrystalline domains. The observed amorphous phase is not the final milling product. After 34 h of milling it was possible to identify by TEM fcc (a = 0.41 nm) nanocrystalline zones, with a mean size of about 10 nm. By irradiating the powder milled for 20 h with high density electron beams, a sudden in situ crystallisation took place. The crystallite (fcc with a = 0.41 nm) size was between 0.1 and 0.5 mu-m.
AMORPHIZATION AND PHASE-TRANSFORMATIONS IN MECHANICALLY ALLOYED TI-AL POWDERS - ELECTRON-MICROSCOPY INVESTIGATION / Bonetti, E; Cocco, G; Enzo, Stefano; Valdre, G.. - In: MATERIALS SCIENCE AND TECHNOLOGY. - ISSN 0267-0836. - 6:12(1990), pp. 1258-1262.
AMORPHIZATION AND PHASE-TRANSFORMATIONS IN MECHANICALLY ALLOYED TI-AL POWDERS - ELECTRON-MICROSCOPY INVESTIGATION
ENZO, Stefano;
1990-01-01
Abstract
The microstructural evolution during mechanical alloying of Ti and Al powders has been investigated by X-ray diffraction, scanning electron microscopy (SEM)-energy dispersive spectroscopy, and transmission electron microscopy (TEM). Observations by SEM showed a progressive change of the powders' morphology as a function of milling time. Observations by TEM, performed on a sample milled for 20 h, revealed the simultaneous occurrence of amorphous zones and nanocrystalline domains. The observed amorphous phase is not the final milling product. After 34 h of milling it was possible to identify by TEM fcc (a = 0.41 nm) nanocrystalline zones, with a mean size of about 10 nm. By irradiating the powder milled for 20 h with high density electron beams, a sudden in situ crystallisation took place. The crystallite (fcc with a = 0.41 nm) size was between 0.1 and 0.5 mu-m.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.