Processing, Microstructure and Mechanical Properties of Al-Fe Based Alloys

초록

Dispersion strengthened Al-Fe based alloys have been widely studied to use them in the field of automobile industries under high temperature environment because Al-Fe based intermetallic dispersoids which are thermally stable even in high temperature region [1]. It has been reported that the strength increases with increase volume fraction of dispersoids and decrease particle size in Al alloys [2]. And mechanical strength at high temperature depends on the thermal stability in not only the matrix phase but also intermetallic dispersoids [3]. Using conventional solidification process, however, it is not easy to control microstructure features, such as refinement of grain size and dispersoids in Al-Fe-TM alloys because most of transition metals with high melting points have narrow solubility in Al alloys. One way to refine the microstructure would be a specific processing technique in terms of a rapid solidification. In this study, we tried to produce the Al-8Fe-2Mo-2V-1Zr alloys using three kinds of rapid solidification methods and subsequent hot extrusion at 673K. Equaxied grains containing Al-Fe, Al-Fe-(Mo, V), and Al-Zr phase particles were characterized. The yield strength of the melt spun and extruded (ME) specimen was estimated to about 800MPa at room temperature, which value is about 1.5times higher than that obtained in the atomized and extruded (AE) specimen and about 2.5times higher than that obtained in the spray formed and extruded (SE) specimen. The ME specimen still exhibited higher strength even in higher temperature region than the AE specimen and the SE specimen. The higher mechanical properties of ME specimen was attributed to its fine grain size and extremely fine dispersoids size.