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Title: Particle coarsening in rapidly solidified Al-Fe-Ce alloys

Abstract

The objective of this study was to examine the stability of the strengthening dispersoids with respect to phase change and Ostwald ripening at elevated temperatures in rapidly solidified Al-Fe-Ce alloys containing 7-9 wt. % Fe and 3-7 wt. % Ce. Five dispersed phases were observed in the as-extruded Al-8.8Fe-3.7Ce and Al-8.9Fe-6.9Ce alloys: metastable Al/sub 6/Fe, two metastable Al-Fe-Ce phases, and equilibrium Al/sub 13/Fe/sub 4/ and Al/sub 10/Fe/sub 2/Ce. By convergent beam electron-diffraction studies, the structure of one of the metastable Al-Fe-Ce phases was found to be orthorhombic, having a = 1.02 nm, b = 1.62 nm, and c = 0.42 nm. The structure of Al/sub 10/Fe/sub 2/Ce was determined to be orthorhombic, having a = 0.894 nm, b = 1.022 nm, and c = 0.906 nm. After aging 2160 hours at 316/sup 0/C, no Al/sub 6/Fe was detected and only rarely were the metastable orthorhombic Al-Fe-Ce particles found. The other metastable Al-Fe-Ce phase persisted. Aging 24 hours at 425/sup 0/C gave only the equilibrium phases. Coarsening of the dispersed phases in the rapidly solidified Al-Fe-Ce alloys occurs much more rapidly than expected by the Modified Lifshitz-Slyozov-Wagner theory for bulk-diffusion-controlled coarsening, although the expected linear relation between particle dimension cubed andmore » time is followed for aging temperatures of 475/sup 0/C and higher. Experimental particle-size distributions are broadened and skewed in the opposite sense to that predicted by the theory.« less

Authors:
Publication Date:
Research Org.:
Northwestern Univ., Evanston, IL (USA)
OSTI Identifier:
5574469
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; PHASE TRANSFORMATIONS; CERIUM ALLOYS; IRON ALLOYS; CRYSTAL LATTICES; DISPERSIONS; HEAT TREATMENTS; PARTICLE SIZE; SOLIDIFICATION; ALLOYS; CRYSTAL STRUCTURE; RARE EARTH ALLOYS; SIZE; 360102* - Metals & Alloys- Structure & Phase Studies

Citation Formats

Angers, L. Particle coarsening in rapidly solidified Al-Fe-Ce alloys. United States: N. p., 1985. Web.
Angers, L. Particle coarsening in rapidly solidified Al-Fe-Ce alloys. United States.
Angers, L. 1985. "Particle coarsening in rapidly solidified Al-Fe-Ce alloys". United States.
@article{osti_5574469,
title = {Particle coarsening in rapidly solidified Al-Fe-Ce alloys},
author = {Angers, L},
abstractNote = {The objective of this study was to examine the stability of the strengthening dispersoids with respect to phase change and Ostwald ripening at elevated temperatures in rapidly solidified Al-Fe-Ce alloys containing 7-9 wt. % Fe and 3-7 wt. % Ce. Five dispersed phases were observed in the as-extruded Al-8.8Fe-3.7Ce and Al-8.9Fe-6.9Ce alloys: metastable Al/sub 6/Fe, two metastable Al-Fe-Ce phases, and equilibrium Al/sub 13/Fe/sub 4/ and Al/sub 10/Fe/sub 2/Ce. By convergent beam electron-diffraction studies, the structure of one of the metastable Al-Fe-Ce phases was found to be orthorhombic, having a = 1.02 nm, b = 1.62 nm, and c = 0.42 nm. The structure of Al/sub 10/Fe/sub 2/Ce was determined to be orthorhombic, having a = 0.894 nm, b = 1.022 nm, and c = 0.906 nm. After aging 2160 hours at 316/sup 0/C, no Al/sub 6/Fe was detected and only rarely were the metastable orthorhombic Al-Fe-Ce particles found. The other metastable Al-Fe-Ce phase persisted. Aging 24 hours at 425/sup 0/C gave only the equilibrium phases. Coarsening of the dispersed phases in the rapidly solidified Al-Fe-Ce alloys occurs much more rapidly than expected by the Modified Lifshitz-Slyozov-Wagner theory for bulk-diffusion-controlled coarsening, although the expected linear relation between particle dimension cubed and time is followed for aging temperatures of 475/sup 0/C and higher. Experimental particle-size distributions are broadened and skewed in the opposite sense to that predicted by the theory.},
doi = {},
url = {https://www.osti.gov/biblio/5574469}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1985},
month = {1}
}

Thesis/Dissertation:
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