Intragranular and Grain Boundary Precipitations with Aging Treatment in Mg-Al System Alloys Poured into Gravity Mold

Abstract:

It is well-known that age hardening occurs in Mg-Al system alloys, when the alloy containing aluminum exceeds 6mass%. This precipitation reaction depends on aluminum content and aging temperature. The aging behavior in AZ91 magnesium alloy was investigated and it is the subject of this paper. However, for the Mg-Al system alloys, the influence of aluminum content on aging hardening characteristics has not been researched in detail so far. In this study, continuous and discontinuous precipitations during aging in Mg-Al system alloys cast into sand and iron molds were investigated by means of hardness measurement and microstructure observation with optical microscopy and transmission electron microscopy. Variation of hardness with aging was found to be caused mainly by the discontinuous precipitation along the grain boundaries from the composite rule in hardness. In iron mold castings, It was found that the variation of hardness with aging was found to be caused mainly by the continuous precipitation inside the crystal grain.

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 1140-1145
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.1140
• Online since: January 2012
• Authors: Mitsuaki Furui, Susumu Ikeno, Seiji Saikawa
• Keywords: Age Hardening Behavior, Grain Boundary Reactions, Intragranular Boundary Reactions, Iron Molds, Magnesium-Aluminum System Alloys, Sand Mold

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