Phase transformation, structural evolution, and mechanical property of nanostructured feal as a result of mechanical alloying

Abstract

The objective of the work is to synthesize nanostructured FeAl alloy powder by mechanical alloying (MEA). The work concentrates on the synthesis, characterization, and structural and mechanical properties of the alloy. Nanostructured FeAl intermetallics are prepared directly by MEA in a highenergy ball mill. Milling is performed under toluene solution to avoid contamination from the milling media and atmosphere. Mixtures of elemental Fe and Al are progressively transformed into a partially disordered solid solution with an average composition of Fe-50 at.% Al. Phase transformation, structural changes, morphology, particle size measurement, and chemical composition during MEA are investigated by X ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS). Vickers microhardness (VMH) indentation tests are performed on the powders. The XRD and SEM studies reveal the alloying of elemental powders as well as transition to nanostructured alloy; crystallite size of 18 nm is obtained after 28 h of milling. Expansion/contraction in lattice parameter accompanied by reduction in crystallite size occurs during transition to nanostructured alloy. Longer milling introduces ordering in the alloyed powders as proved by the presence of superlattice reflection. Elemental and alloyed phases coexist while hardness increases during MEA.

The magnetic and structural properties of nanostructured (Fe75Al25) 100-xBx alloys prepared by mechanical alloying

“…With increasing MA time up to 80 h, they found that the angular position of the peak (1 1 0) slightly shifted to a higher 2θ value and they attributed this shift to the ordering in the alloyed powders. In addition, Rajath Hegde et al[15] reported that the Fe(Al) solid solution was transformed into an ordered FeAl phase after 28 h of milling in the case of Fe50Al50. On the other hand, we can see inFig.3.b that the peak of Al disappeared after 26 h milling.…”

Structure and phase composition of deformed heat-affected zone of the weld steel St3

“…The test machine INSTRON-1185 was used in this experiment to measure tensile strength of the steel specimen subjected to a quasi-static tensile deformation ranging from 0 to = 5 % under 370 MPa loading. Tensile stress testing was accompanied by recording the acoustic emission and measuring the acoustic delay using the acoustic-surfacewave technique (Anstron) during the load achieving and removal [1,2]. The investigations were carried out in the heat-affected zone (HAZ) in two points, namely: 1) base material at 1 mm distance from the joint between the deposited and base metals; 2) welded joint metal at 0.5 mm distance from the joint.…”

“…The structural and phase condition of metal that is formed during welding, affects the mechanical-and-physical properties of products [1][2][3][4]. The modification of the structural and phase conditions in the course of operation and, especially, during deformation that often occurs in welded articles, can lead to adverse effects [2][3][4].…”

“…the heat-affected zones. Heat-affected zones is the most dangerous stress concentrator resulting in the formation of cracks and other defects [4], that considerably dcrease the strength and durability of welded articles [1][2][3]. Knowledge of the structural and phase conditions of the material and heat-affected zones in particular, provides not only the assesment of the strength properties of welded article but also the behavior of welded joint during the operation.…”

The structure and phase composition of welded joint after deformation

“…The quality improvement is based on knowledge of the processes that determine the formation and properties of welded joints. There is currently a great deal of different welding techniques [1][2][3][4][5][6][7][8][9][10][11][12][13], each of which has advantages and drawbacks of their own. As described in works [13][14][15][16], the mechanical and physical properties of products are affected, first of all, by the structural and phase conditions of metal that are formed due to welding.…”