The synthesis and characterization of ultrafine grain NiAl intermetallic

Processing behavior of nanocrystalline NiAl during milling, sintering and mechanical loading and interpretation of its intergranular fracture

“…It is mentioned that in an annealed metal, for example, there is about 10 10 -10 12 dislocations per cm 2 [15]. Table 1 presents a comparison between mechanical properties of NiAl product in our work and literature [5,8,9,24,[27][28][29][30][31][32][33]. Little difference between the results of this work with literature (milling & sinter) can be related to the negligible difference amounts of porosity and grain size of products resulted from different sintering conditions.…”

“…6b and c shows the fracture surface of sintered NiAl in different magnifications. Fracture mode was intergranular same as literature [8,26]. Also, no obvious pores and voids were observed on SEM images (Fig.…”

“…(1). For metallic and intermetallic powders, it is believed that fracturing and cold welding are not the major mechanisms for the grain size reduction [8]. Instead, the grain size reduction is due to the three other mechanisms: (1) localization of plastic deformation (non-homogeneous deformation) in the form of shear bands containing a high density of dislocations, (2) formation of subgrains or cells by annihilation of dislocations, and (3) the conversion of subgrains/cells into grains through mechanically driven grain rotation and subgrain boundary sliding.…”

“…refinements have been an active research area [7]. Although some researches focused on the production coarse grain (CG) and ultrafine grains (UFG) of NiAl [4,5,8,9], it's mechanical properties needs to be more studied.…”

Structural and microstructural phase evolution during mechano-synthesis of nanocrystalline/amorphous CuAlMn alloy powders

“…Among the mechanical alloying routes, ball milling process is one of the most common methods in which the powder particles are subjected to repeated cold welding, fragmenting and re-welding, causing an atomic scale alloying [16][17][18]. By using the MA process, not only the control of microstructure and chemical composition homogeneity is feasible, but also the formation of non-equilibrium phases such as nanocrystalline/amorphous phases, intermetallic phases, and supersaturated solid solutions is achievable [17][18][19][20][21][22].…”