Effect of ultrasonic vibration pretreatment on microstructural evolution and mechanical properties of extruded AZ91 alloy

Abstract

An AZ91 alloy pretreated by ultrasonic vibration (UV) was subjected to extrusion to refine the microstructure. The results indicated that the UV pretreatment had a strong influence on the microstructure evolution and mechanical properties of the extruded AZ91 alloy. With UV pretreatment, a fine and uniform microstructure with an average grain size of 13.5 μm was obtained, and the fraction of the fiber-like, partiallyrecrystallized, structure was markedly reduced. In addition to the superior mechanical properties such as a yield strength of 256MPa, an ultimate tensile strength of 320 MPa and a fracture elongation of 9.7% were achieved in the extruded AZ91 alloy with UV pretreatment, © 2008 The Japan Institute of Metals.