Phase transformation in a rapidly solidified Al-8.3Fe-1.9V-2.1Si alloy

Al-Fe-V-Si alloys can be rapidly solidified and consolidated by means of hot isostatic pressing and extrusion to produce the structures which contain very small iran aluminide precipitates, thereby opening a new avenue to the design of advanced aluminum alloys with a larger volume fractions of iron aluminide precipitates. Such alloys possess high strength at elevated temperatures. The purpose of the present study is to examine the formation of the iran aluminide phase and the thermal stability of rapidly solidified Al-8.3Fe-1.9V-2.1Si, The Al-8.3Fe-1.9V-2.1Si alloy was rapidly solidified from the melt, the molten droplets formed by gas atomization being quenched in high velocity water on a rapidly-rotating copper wheel. The average diameter of powder was about 17 mu m. The phases present in as-rapidly solidified Al-8.3Fe-1.9V-2.1Si alloy powders and the phase transformation during heating were investigated by using scanning electron microscope, X-ray diffraction and differential thermal analysis. The results show that the microstructures of as-rapidly solidified powders consist of alpha(Al) and Al-13(Fe,V)(3)Si phases. The addition of V to the Al-Fe-Si system is essential to stabilize the metastable Al13Fe3Si phase that is otherwise susceptible to coarsening at moderately elevated temperature. At temperatures between 638 degrees C and 645 degrees C, the cubic Al-13(Fe, V)(3)Si phase transforms to the hexagonal Al-3(Fe, V, Si) phase.