The effects of Sc and Zr addition on the microstructure and properties of an in situ nano ZrB₂-reinforced 7085Al composite

Abstract

To achieve great strength and ductility the effects of Sc and Zr on the microstructure and properties of 7085Al reinforced by in situ ZrB₂ nano particles were investigated. The 7085Al-3wt.%ZrB₂ composites were prepared by in situ reaction with the reaction of K₂ZrF₆ and KBF₄ salts. Minor addition of Sc and Zr resulted in significant strength increased through the formation of fine Al₃(Sc Zr) dispersoids that refined the crystal grain and modified the distribution and morphology of in situ ZrB₂ and precipitates along the grain boundaries. Comparing to the traditional microalloying of aluminum matrix alloy reinforced by particles the aim of this study was to break the limitation of reinforcing phases containing and to explore the cooperation effects between ZrB₂ and Al₃(Sc Zr) dispersoids. Tensile tests showed that the ultimate tensile strength (UTS) yield strength (YS) and elongation increased to 670MPa 550MPa and18.65% respectively which indicated the increase of 28.2% 19.5% and 83.3% respectively compared to the matrix alloy.