Synthesis and sturctural characterization of nanocrystalline al-10at.%Li powder prepared by mechanical alloying

The technique of mechanical alloying has been used to obtain nanocrystalline structure of Al-10 at.% Li alloy. For this purpose, pure aluminum powder was mixed with crushed lithium particles with a nominal composition Al90Li10 was subjected to intense mechanical alloying in an attrition ball mill under high purity argon gas atmosphere. Then they attrition milled for 20 hours. Morphologic evolution and variations in grain size, powder particle size, lattice parameter and phase transformations in 5 hour time interval of milling was characterized through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Crystallite size, lattice strain and lattice parameter were determined by Williamson-Hall and Nilson-Reley methods. Based on the characterization results, grain size was fallen to 50 nanometers after 20 hours of milling. In primary hours of milling, system shows more tendencies to form solid solution rather than intermetallics. However, with increasing milling time, the solid solution was not stable anymore and intermetallic of AlLi established instead of solid solution. The more the lithium content in powder mixture, the more the percentage of intermetallic would be in final milled powder

Keywords:

Aluminum-Lithium alloy , non-equilibrium processing , Mechanical alloying , Williamson-Hall , Nilson–Reley , Scanning electron microscopy , particles size