Microhardness and morphologic characteristics of rapidly solidified Al-12Si-8Ni-5Nd alloy

Abstract

Al-Si-Ni-Nd alloys with a nominal composition of Al-12 wt.% Si-8 wt.% Ni-5 wt.% Nd alloy are prepared by a conventional casting (ingot) and melt spinning technique at different cooling rates (v). The effects of the rapid solidification rate on the microstructures and microhardness performances of the specimen alloys are investigated in detail. The results obtained by the XRD, SEM and DSC show that the ingot and melt spun alloys have a multiphase structure. When v is 5 m/s, the alloy consists of four phases namely α-Al, intermetallic Al 3 Ni, Al 11 Nd 3 , and fcc Si. The melt-spun ribbons are completely composed of α-Al and eutectic Si phases, and primary silicon is not observed when v increases to 20 m/s, 25 m/s, 30 m/s and 35 m/s. The XRD analysis indicated that the solubility of Si in the α-Al matrix increases greatly with the rapid solidification. The change in microhardness is discussed based on the microstructural observations. The microhardness values of the melt spun ribbons are about three times higher than those of ingot counterparts.