Characterization of Mechanically Alloyed Nanocrystalline Fe(Al): Crystallite Size and Dislocation Density

Abstract

A nanostructured disordered Fe(Al) solid solution was obtained from elemental powders of Fe and Al using a high-energy ball mill. The transformations occurring in the material during milling were studied with the use of X-ray diffraction. In addition lattice microstrain, average crystallite size, dislocation density, and the lattice parameter were determined. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Thermal behaviour of the milled powders was examined by differential scanning calorimetry (DSC). The results, as well as dissimilarity between calorimetric curves of the powders after 2 and 20 h of milling, indicated the formation of a nanostructured Fe(Al) solid solution.

Structural characterization of mechanically alloyed nanocrystalline Cu-Fe: Strain broadening due to dislocations

“…It is worth noting that the maximum of lattice parameters is for 40h of milling. The variation of the lattice parameter as a function of milling time can be correlated to the change in composition and/or to the lattice expansion due to the increase in the density of dislocations with their characteristic strain fields on the nanograin boundary [12,17,18]. The decrease of the amplitude and the increase of the broadening of the Bragg peaks with milling time can be explained by the contribution of the 00048-p. 4 effective crystallite size and an increase of the lattice strains.…”

“…Hence dislocations are considered to be responsible for the final MA state. So, for MA samples, the density of dislocations, ρ, is represented in terms of the crystallite size, D and the lattice strains ε by [17]:…”

Evolution of crystallite size, lattice parameter and internal strain in Al precipitates during high energy ball milling of partly amorphous Al87Ni8La5 alloy

“…It has been reported that the lattice parameter increases or decreasesas a function of the crystallite size [14,[24][25][26][27].There are several models which describe thecorrelationof the lattice parameter with the crystallite size based on (a) the surface energy [28][29][30], (b) the lack of the outermost bonding of the surface atoms [31],and (c) intra-crystalline pressure [32,33]. According to Qi et al [14] the decrease in the lattice parameter ( ಲ ሺ୲ୀ ሻି ಲ ሺ౪ሻ ಲ ሺ୲ୀ ሻ ൌ ࢤ )of aluminumdepends on the surface energy ࢽ, thecrystallite shape Į(Į=1 for spherical shape), the shear modulusGand the crystallite size D.According to Qi et al [14]the changes of the lattice parameter ( ௱ బ )of Al nanocrystals in ball milled Al 87 Ni 8 La 5 can be described by…”

Design of light weight multi-layered coating of zinc oxide–iron–graphite nano-composites for ultra-wide Bandwidth microwave absorption

“…Further increasing the milling time to 20 h (S7) results in the recrystallization in the sample, accordingly there is an increase in the grains size as illustrated in XRD pattern ( Fig. 2; Table 2) [30][31][32]. The above study clearly indicates the role of internal strain in the materials dielectric and magnetic losses.…”

“…It can be observed that no extra peak or phase is present in the XRD patterns of ''as prepared'' samples even after ball milling for 5, 10, 15 and 20 h. In the given XRD patterns, it is clearly visible that the peak broadening increases and intensity of the peak decreases as the time of ball milling increases except in the case of 15 h milled sample. The peak broadening has decreased while intensity of the peak has increased in 15 h ball milled sample, it may be due to re-crystallization in the sample [30][31][32]. Each particle contains number of grains and the average grain size of the samples were calculated using Debye Scherer's formula, which is shown in Table 2.…”