Phase transformation reactions in rapidly solidified Al-6.5Fe-1.5V alloys

Phase transformation reactions, occurring during heating of as-atomised Al- 6.5Fe-1.5V powders, extrusion of the powders, and heating of the as-extrude d alloys produced from the powders, have been studied by DSC, XRD and TEM. The DSC studies of the as-atomised powders revealed several phase transform ation reactions. The solid solution in zone A decomposed to form metastable phases at 360 degreesC. These metastable phases further transformed to for m equilibrium phases at 500 degreesC. The microquasi-crystalline icosahedra l (MI) phase particles present in zone A and zone B transformed to equilibr ium phases at 500 degreesC. The globular clusters of microquasi-crystalline icosahedral (GCMI) phase particles in zone C transformed polymorphously to icosahedral (I) phase particles at 450 degreesC. These reactions were beli eved to occur during extrusion of the powders. During heating of the as-ext ruded alloys produced from coarse powder particles, I phase transformed pol ymorphously to hexagonal phase at 550 degreesC. The hexagonal phase decompo sed to monoclinic Al(4)5(V, Fe)(7) and Al(1)3Fe(4) phases upon heating for longer times. (C) 2001 Kluwer Academic Publishers.