ELECTRON-MICROSCOPY OF METASTABLE PHASES IN RAPIDLY SOLIDIFIED AL-CO ALLOYS

被引:7
|
作者
SURYANARAYANA, C
MENON, J
机构
[1] UNIV WINDSOR,DEPT MECH ENGN,ENGN MAT GRP,WINDSOR N9B 3P4,ONTARIO,CANADA
[2] BANARAS HINDU UNIV,DEPT MET ENGN,VARANASI 221005,UTTAR PRADESH,INDIA
关键词
AL-CO ALLOYS; TRANSMISSION ELECTRON MICROSCOPY; RAPID SOLIDIFICATION; SUPERSATURATED SOLID SOLUTIONS; METASTABLE INTERMEDIATE PHASES; DECAGONAL QUASI-CRYSTALLINE PHASE; POLYTYPISM; AMORPHOUS PHASE; TRANSFORMATION STUDIES;
D O I
10.1007/BF02747560
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Four binary AL-Co alloys containing 2.4, 14, 20 and 25 at.%Co and a ternary AL-Co-Si alloy with 20 at.% Co and 5 at.% Si were rapidly solidified from the liquid state by melt spinning. It has been shown that the solid solubility of Co in Al can be increased up to at least 1.7at.% from the negligible value under equilibrium conditions. Two metastable crystalline intermediate phases and a D1a-type ordered phase were observed in localized regions in the rapidly solidified Al-2-4at.%Co alloy. A quasicrystalline decagonal phase has been observed in all the other rapidly solidified alloys. This decagonal phase was shown to contain dislocations, dislocation loops and also twin-like defects. The phenomenon of polytypism was also observed in this decagonal quasicrystalline phase. In extremely thin areas of the Al-14at.%Co alloy ribbons on amorphous phase was detected. Transmission electron microscopy was used to extensively characterize the phases in the as-solidified condition and also those produced during and after transformation to the equilibrium constitution.
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页码:121 / 139
页数:19
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