Abstract

Optical microstructures and mechanical properties of Na gas atomized Al-20Si-5Fe alloying powder and its hot extrudates were studied on 3 different types of powder size distribution. This powder showed the size distribution of 10~210 mutextrmm. Also the microstructures of alpha-Al, primary and eutectic Si and needle shaped intermetallic compounds were observed by optical microscope. These needle shaped intermetallic compounds were identified as deltaAl_4FeSi_2- by XRD and EDX analysis. The ultimate tensile strength(UTS) of these alloy extrudates was increased from 324 to 390 MPa with decreasing powder size range from 120~210 mutextrmm to 10~64 mutextrmm. A value of Micro-vic-kers hardness was simillar to the result of UTS. These extrudates showed better wear resistance than those of Al-20Si-2X(X : Ni, Cr, Zr), although they are insensitive to the size distribution. These results indicate that the presentation of deltaAl_4FeSi_2 intermetallic compounds contributed to the wear resistance improvement.