Synthesis and Characterization of NanocrystallineMg-7.4%Al Powders Produced by Mechanical Alloying

Abstract

Nanocrystalline Mg-7.4%Al powder was prepared by mechanical alloying using a high-energy mill. The evolution of the various phases and their microstructure, including size and morphology of the powder particles in the course of milling and during subsequent annealing, were investigated in detail. Room temperature milling leads to a rather heterogeneous microstructure consisting of two distinct regions: Al-free Mg cores and Mg-Al intermixed areas. As a result, the material is mechanically heterogeneous with the Mg cores displaying low hardness (40-50 HV) and the Mg-Al intermixed regions showing high hardness of about 170 HV. The Mg cores disappear and the microstructure becomes (also mechanically) homogeneous after subsequent cryo-milling. Rietveld structure refinement reveals that the crystallite size of the milled powders decreases with increasing the milling time reaching a minimum value of about 30 nm. This is corroborated by transmission electron microscopy confirming an average grain size of ~25 nm.

Effect of Particle Size on Microstructure and Mechanical Properties of Al-Based Composite Reinforced with 10 Vol.% Mechanically Alloyed Mg-7.4%Al Particles

“…The reinforcement (Mg-7.4%Al mechanically alloyed particles) was prepared by mechanical alloying of elemental Mg (250 µm, Alfa Aesar, Karlsruhe, Germany) and Al (44 µm, Alfa Aesar) powders in a planetary ball mill for 100 h at room temperature followed by 3 h cryo-milling in liquid nitrogen. The detailed production and characterization of the reinforcement (Mg-7.4Al (wt.%)) has been reported elsewhere [23]. To study the effect of particle size, the composites were prepared with different particle sized reinforcement (0 < D < 20 µm (0-20 µm), 20 ≤ D < 40 µm (20-40 µm), 40 ≤ D < 80 µm (40-80 µm) and 80 ≤ D < 100 µm (80-100 µm)).…”

Comparative Morphological and Crystallographic Analysis of Electrochemically- and Chemically-Produced Silver Powder Particles

“…The main techniques for production of metal powders are: atomization processes, melt spinning, rotating electrode process (REP), mechanical and chemical processes [1,2]. Metal powders are characterized by their morphology and size of the formed particles.…”

Structure and Physical Properties of NiO/Co3O4 Nanoparticles

“…The acquirement of the desired physical and chemical properties from metal oxide NPs requires an effective preparation method and has become a significant subject of research. There are several nonconventional techniques in order to achieve high quality metal oxide nanoparticles that have been used or are under development for preparing ultrafine nanostructures [7][8][9][10][11][12][13][14][15][16][17][18]. Numerous factors and various precipitation agents were utilized to synthesis magnetic metal oxide nanocrystals with specific structures.…”