Abstract: Rapidly solidified hypereutectic Al-21Si and Al-30Si alloys were prepared by a single roller melt-spinning technique. The microstructure and phases of the alloys were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Fine grains with a micro-nano composite microstructure were obtained by rapid solidification. The microstructures of the Al-21Si alloys were characterized by primary micro-nanostructured α-Al phase and feather-needle-like α-Al+β-Si eutectic. The nucleation and growth of primary silicon were effectively inhibited. α-Al phase had a higher priority to nuclate and grow than eutectic α+Si phase. The hypereutectic Al-21Si alloy showed the hypoeutectic microstructure. The primary Si phases in Al-30Si alloy were fine twins. And this microstructures were a typical hypereutectic microstructure. Microhardness and wear resistance (i.e. 5 times as high as that of traditional casting alloys) of alloys were greatly improved by rapidly solidification.

Key words: rapid solidification, hypereutectic Al-Si alloys, microstructure, micro-nanocrystalline, wear resistance

Author: LI Jiwen, 1. College of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471003, China; 2. Henan Engineering Research Center for Wear Resistance Materials, Luoyang 471003, China

E-mail: ljwzq@163.com

Tribology, Vol. 30, Issue 2, 2010, 111~117