Reactions in Al2O3Mg metal matrix composites during prolonged heat treatment at 400, 550 and 600°C

Bengt Hallstedt, Zi Kui Liu, John Ågren

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Al2O3Mg metal matrix composites were heat treated for up to several hundred hours at 400, 550 and 600 °C. Samples were prepared and studied using optical microscopy, scanning electron microscopy and transmission electron microscopu. At the two higher temperatures extensive reaction between δ-Al2O3 fibres and the Mg matrix had occurred after 200-300 h. During this time Mg and Al2O3 reacted to form MgO (but not spinel) and Al, which dissolved into the matrix. When the Al solubility in solid Mg was exceeded, liquid started to form. The formation of liquid probably started locally, i.e. long before the bulk matrix composition reached the solubility limit, possibly in metallic films separating growing MgO-grains from shrinking δ-Al2O3 grains, thus increasing the reaction rate drastically. At the end of these heat treatments a major part of the matrix was liquid. Upon cooling the liquid formed a eutectic structure consisting of h.c.p.-Mg and the intermetallic γ-phase. H.c.p.-Mg here refers to solid Mg which has the h.c.p.-structure and dissolves Al. In parallel with the reaction between Mg and Al2O3, there was a continuous coarsening of MgO and very large faceted grains were found. Below the eutectic temperature (437 °C) in the AlMg system liquid can no longer form and an abrupt decrease in reaction rate is expected. Consequently, no reaction was observed after 740 h at 400 °C. It may thus be concluded that long-term service at elevated temperature will not lead to extensive reaction between matrix and fibres as long as the temptemperature is below 437 °C.

Original languageEnglish (US)
Pages (from-to)149-157
Number of pages9
JournalMaterials Science and Engineering A
Volume169
Issue number1-2
DOIs
StatePublished - Sep 15 1993

Fingerprint

metal matrix composites
heat treatment
Metals
Heat treatment
Composite materials
Liquids
matrices
liquids
eutectics
Eutectics
Reaction rates
reaction kinetics
solubility
Solubility
Metallic films
fibers
Fibers
Coarsening
Film growth
Temperature

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

@article{efe73cc69a69461db19b76e7f2f837d4,
title = "Reactions in Al2O3Mg metal matrix composites during prolonged heat treatment at 400, 550 and 600°C",
abstract = "Al2O3Mg metal matrix composites were heat treated for up to several hundred hours at 400, 550 and 600 °C. Samples were prepared and studied using optical microscopy, scanning electron microscopy and transmission electron microscopu. At the two higher temperatures extensive reaction between δ-Al2O3 fibres and the Mg matrix had occurred after 200-300 h. During this time Mg and Al2O3 reacted to form MgO (but not spinel) and Al, which dissolved into the matrix. When the Al solubility in solid Mg was exceeded, liquid started to form. The formation of liquid probably started locally, i.e. long before the bulk matrix composition reached the solubility limit, possibly in metallic films separating growing MgO-grains from shrinking δ-Al2O3 grains, thus increasing the reaction rate drastically. At the end of these heat treatments a major part of the matrix was liquid. Upon cooling the liquid formed a eutectic structure consisting of h.c.p.-Mg and the intermetallic γ-phase. H.c.p.-Mg here refers to solid Mg which has the h.c.p.-structure and dissolves Al. In parallel with the reaction between Mg and Al2O3, there was a continuous coarsening of MgO and very large faceted grains were found. Below the eutectic temperature (437 °C) in the AlMg system liquid can no longer form and an abrupt decrease in reaction rate is expected. Consequently, no reaction was observed after 740 h at 400 °C. It may thus be concluded that long-term service at elevated temperature will not lead to extensive reaction between matrix and fibres as long as the temptemperature is below 437 °C.",
author = "Bengt Hallstedt and Liu, {Zi Kui} and John {\AA}gren",
year = "1993",
month = "9",
day = "15",
doi = "10.1016/0921-5093(93)90609-I",
language = "English (US)",
volume = "169",
pages = "149--157",
journal = "Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing",
issn = "0921-5093",
publisher = "Elsevier BV",
number = "1-2",

}

Reactions in Al2O3Mg metal matrix composites during prolonged heat treatment at 400, 550 and 600°C. / Hallstedt, Bengt; Liu, Zi Kui; Ågren, John.

In: Materials Science and Engineering A, Vol. 169, No. 1-2, 15.09.1993, p. 149-157.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Reactions in Al2O3Mg metal matrix composites during prolonged heat treatment at 400, 550 and 600°C

AU - Hallstedt, Bengt

AU - Liu, Zi Kui

AU - Ågren, John

PY - 1993/9/15

Y1 - 1993/9/15

N2 - Al2O3Mg metal matrix composites were heat treated for up to several hundred hours at 400, 550 and 600 °C. Samples were prepared and studied using optical microscopy, scanning electron microscopy and transmission electron microscopu. At the two higher temperatures extensive reaction between δ-Al2O3 fibres and the Mg matrix had occurred after 200-300 h. During this time Mg and Al2O3 reacted to form MgO (but not spinel) and Al, which dissolved into the matrix. When the Al solubility in solid Mg was exceeded, liquid started to form. The formation of liquid probably started locally, i.e. long before the bulk matrix composition reached the solubility limit, possibly in metallic films separating growing MgO-grains from shrinking δ-Al2O3 grains, thus increasing the reaction rate drastically. At the end of these heat treatments a major part of the matrix was liquid. Upon cooling the liquid formed a eutectic structure consisting of h.c.p.-Mg and the intermetallic γ-phase. H.c.p.-Mg here refers to solid Mg which has the h.c.p.-structure and dissolves Al. In parallel with the reaction between Mg and Al2O3, there was a continuous coarsening of MgO and very large faceted grains were found. Below the eutectic temperature (437 °C) in the AlMg system liquid can no longer form and an abrupt decrease in reaction rate is expected. Consequently, no reaction was observed after 740 h at 400 °C. It may thus be concluded that long-term service at elevated temperature will not lead to extensive reaction between matrix and fibres as long as the temptemperature is below 437 °C.

AB - Al2O3Mg metal matrix composites were heat treated for up to several hundred hours at 400, 550 and 600 °C. Samples were prepared and studied using optical microscopy, scanning electron microscopy and transmission electron microscopu. At the two higher temperatures extensive reaction between δ-Al2O3 fibres and the Mg matrix had occurred after 200-300 h. During this time Mg and Al2O3 reacted to form MgO (but not spinel) and Al, which dissolved into the matrix. When the Al solubility in solid Mg was exceeded, liquid started to form. The formation of liquid probably started locally, i.e. long before the bulk matrix composition reached the solubility limit, possibly in metallic films separating growing MgO-grains from shrinking δ-Al2O3 grains, thus increasing the reaction rate drastically. At the end of these heat treatments a major part of the matrix was liquid. Upon cooling the liquid formed a eutectic structure consisting of h.c.p.-Mg and the intermetallic γ-phase. H.c.p.-Mg here refers to solid Mg which has the h.c.p.-structure and dissolves Al. In parallel with the reaction between Mg and Al2O3, there was a continuous coarsening of MgO and very large faceted grains were found. Below the eutectic temperature (437 °C) in the AlMg system liquid can no longer form and an abrupt decrease in reaction rate is expected. Consequently, no reaction was observed after 740 h at 400 °C. It may thus be concluded that long-term service at elevated temperature will not lead to extensive reaction between matrix and fibres as long as the temptemperature is below 437 °C.

UR - http://www.scopus.com/inward/record.url?scp=0027664062&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027664062&partnerID=8YFLogxK

U2 - 10.1016/0921-5093(93)90609-I

DO - 10.1016/0921-5093(93)90609-I

M3 - Article

AN - SCOPUS:0027664062

VL - 169

SP - 149

EP - 157

JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

SN - 0921-5093

IS - 1-2

ER -