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Title: Microstructure, microstructural stability and mechanical properties of sand-cast Mg–4Al–4RE alloy

This paper presents a methodology for assessing the phase composition and the results of structural stability tests of the sand-cast Mg–4Al–4RE alloy after annealing it at 175 and 250 °C for 3000 h. The microstructure was analyzed with optical, scanning electron, and transmission electron microscopy. The phase composition was determined with X-ray diffraction. The structure of the Mg–4Al–4RE (AE44) alloy is composed of large grains of α-Mg solid solution, needle-shaped precipitates of the Al{sub 11}RE{sub 3}phase, polyhedral precipitates of the Al{sub 2}RE phase and Al{sub 10}RE{sub 2}Mn{sub 7} phase. After annealing at 175 °C for 3000 h, no changes in the alloy structure are observed, whereas after annealing at 250 °C the precipitates of the Al{sub 11}RE{sub 3} phase are found to be in the initial stages of spheroidization. The coarse-grained structure and unfavorable morphology of the intermetallic phases in the sand-cast AE44 alloy, which are caused by low solidification rates, result in low creep resistance up to 200 °C and low mechanical properties at ambient temperature and at 175 °C. - Highlights: • Complement the knowledge about the microstructure of Mg-Al-RE alloys. • Clarify the mechanism of formation of Mg17Al12 phase above 180 °C. • Applying a chemical dissolutionmore » of the α-Mg in order to phase identification. • Applying a statistical test to assess the spheroidization of precipitates. • Quantitative description of microstructure of Mg-Al-RE alloys.« less
Authors:
 [1] ;  [1] ;  [2]
  1. Silesian University of Technology, Faculty of Materials Science and Metallurgy, Krasińskiego 8, 40 019 Katowice (Poland)
  2. Polish Academy of Sciences, Institute of Metallurgy and Materials Science, 25 Reymonta Street, 30-059 Kraków (Poland)
Publication Date:
OSTI Identifier:
22285074
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 83; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CREEP; MAGNESIUM ALLOYS; METALLOGRAPHY; MICROSTRUCTURE; PRECIPITATION; SAND; SOLID SOLUTIONS; SOLIDIFICATION; STABILITY; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION