ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract A study of the structural changes occurring during the processing of a rapidly solidified powder aluminium alloy has been performed. Considerable microstructural differences have been noted from among different powder particles and from within the same particle. Three typical microstructures were observed; small particles exhibited a microcellular structure, medium-sized particles a dual morphology of microcellular and cellular structure, whilst in the large particles coarse intermetallics were formed during solidification, acting as nucleation sites for a cellular aluminium structure. Apart fromα-Al three other phases were detected in the powder microstructure, Fe4Al13, (Fe, Mn)Al6 and an unidentified phase termed “F”. The formation of both spheres and needle particles was promoted at high temperatures irrespective of the type of phase (Fe4Al13 or (Fe, Mn)Al6). It has been shown that the heterogeneity of the microstructural features was maintained during subsequent consolidation via extrusion. The influence of heating and deformation modifies the microstructures but was insufficient to produce a uniform microstructure. The decomposition behaviour of the different microstructures has been examined in detail and the heterogeneities in the extrudate could be related to the powder microstructure and ultimately the solidification behaviour during atomization. The microstructural heterogeneity of the extrudates was characterized by the formation of long bands which normally contained two types of structure. Bands with a high volume fraction of needle-like precipitates and bands with a high volume fraction of spheroids originated from the microcellular and coarser cellular structure, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01154621
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