An analysis of the microstructure of rapidly solidified Al-8 wt pct Fe powder |
| |
Authors: | W J Boettinger L Bendersky J G Early |
| |
Affiliation: | (1) Metallurgy Division, National Bureau of Standards, 20899 Gaithersburg, MD;(2) Center for Materials Science, The Johns Hopkins University, 21218 Baltimore, MD |
| |
Abstract: | Rapidly solidified powders of Al-8 wt pct Fe exhibit four distinct microstructures with increasing particle diameter in the
size range of 5 μm to 45 μm: microcellular α-Al; cellular α-Al; a-Al + Al6Fe eutectic; and Al3Fe primary intermetallic structure. Small powder particles (~10 μm or less) undercool significantly prior to solidification
and typically exhibit a two-zone microcellular-cellular structure in individual powder particles. In the two-zone microstructure,
there is a transition from solidification dominated by internal heat flow during recalescence with high growth rates (microcellular)
to solidification dominated by external heat flow and slower growth rates (cellular). The origin of the two-zone microstructure
from an initially cellular or dendritic structure is interpreted on the basis of growth controlled primarily by solute redistribution.
Larger particles experience little or no initial undercooling prior to solidification and do not exhibit the two-zone structure.
The larger particles contain cellular, eutectic, or primary intermetallic structures that are consistent with growth rates
controlled by heat extraction through the particle surface (external heat flow). |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|