Evaluation of Near-surface Microstructure on Al-alloy treated by Fine Particle Bombarding Process

Abstract

In this study, fine particle bombarding treatment (FPB) was applied to A5052 aluminum alloy, the effects of FPB treatment time (5, 10, 20, 40s) on the near-surface microstructure hardness, and fatigue strength was examined. The near-surface microstructure of 20s and 40s FPBed Al-Alloy was nano-crystallized, and lamellar structures were partially formed. The average grain sizes in and around lamellar structure are 65nm and 125nm by TEM observation. The relationship between hardness and grain size indicates Hall-Petch relationship. Moreover, fatigue tests were carried out with cantilever-type rotary bending fatigue test machine. Fatigue strength of 20s-FPBed Al Alloy is highest, the relationship between fatigue strength and grain size indicates linearity. Then 20s-FPBed A5052 had the fatigue strength equivalent to 7000 series aluminum alloys.