Precipitation in Rapidly Solidified Al-Mn Alloys
JOHNS HOPKINS UNIV BALTIMORE MD CENTER FOR MATERIALS RESEARCH
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Precipitation at 450 C was studied in melt-spun ribbons containing up to 15 wt. Mn in solid solution in Al. The as-spun ribbons were microsegregation-free at compositions up to 5 wt. Mn, but in more concentrated alloys a cellular micro-structure was present. Upon annealing, four precipitate phases are observed, some of them being found preferentially on cell boundaries and others within the cells. Al6Mn, G and the G phase can coexist for long times at 450 C, but the G phase appears to be slightly more stable. A less stable T phase was detected in Al-5 wt. Mn foils following short annealing periods. The supersaturation of the Al matrix can persist for many hours in alloys containing up to 3 wt. Mn, but is essentially gone after 1 hour in alloys with 5 wt. Mn or more.
- Properties of Metals and Alloys