Hot extrusion and characterization of an Al-Fe-VorNb-Si powder alloy prepared by high energy milling

Abstract

This paper presents the microstructural and mechanical characterization of an alloy, Al90.8- Fe6.2-(VorNb)1.0-Si2.0 (at%), prepared by high energy milling elemental powders of Al, Fe, V and Si, followed by vacuum hot pressing and hot extrusion. The powders were milled for 10 hours at 800 and 1400 rpm and the extruded bars were characterized by X ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive analysis of selected areas. The following phases were found in the extruded bars: Al8Fe2Si, Al12(Fe,V)3Si in the alloy with V and Al8Fe2Si, Al12(Fe,Nb)3Si, and AlNb2 in the alloy with Nb. Tensile tests and Vickers hardness at room temperature were carried out on the extruded bars. The bars from powders milled at 1400 rpm showed the highest strength and hardness and are similar to those obtained by rapid solidification in the alloy Al-Fe-V-Si. The improved mechanical properties of these bars could be attributed to the dispersoids in the microstructure.