Surface treatment of Al18B4O33 whisker and development of Al18B4O33/ZK60 magnesium alloy matrix composite

In order to improve high temperature properties and good aging behavior of ZK60 (Mg-6%Zn-0.6%Zr) magnesium alloy moreover, Al18B4O33 whisker reinforced composites were developed. Al18B4O33 whisker reacts with ZK60 alloy thermodynamically. In order to suppress the interfacial reaction between Al18B4O33 and molten state ZK60 matrix, as-received whiskers were surface treated chemically. Whisker surface in preform was coated in vacuum by pure magnesium vapor, and then heat-treated at atmosphere. By the chemical reaction of whisker, MgAl2O4 layer with 10-20 nm in thickness was produced on the whisker and covered with whisker completely. Then, Al18B4O33/ZK60 magnesium alloy matrix composite was fabricated by squeeze casting process. As the preform with surface treated whisker is stable for molten ZK60 alloy, the interfacial reaction did not occur during fabrication process and heat treatment after fabrication. The composites have good aging behavior because of no reaction in the interface. Although the precipitation tended to occur around interface preferentially during aging, but the obvious age hardening behavior were observed. (c) 2006 Elsevier B.V. All rights reserved.