Microstructure and Tensile Properties of ZK60 Alloy Fabricated by Simplified Rapid Solidification Powder Metallurgy (S-RS P/M) Process

摘要

This study investigated the microstructures and mechanical properties of ZK60 alloy prepared by a simplified rapid solidification powder metallurgy (RS P/M) processing system (S-RS P/M), which consists of warm press in dry air and hot extrusion. Microstructure characterizations showed that S-RS P/M alloy consisted of magnesium matrix and oxide stringers of～1 μm in width. TEM (transmission electron microscopy) observations illustrated nano-size magnesia particles (10-30 nm) constituted oxide stringer in detail. Due to a relatively higher volume of nano-size magnesia particle produced during S-RS P/M process, 0.2% yield strength of S-RS P/M ZK60 alloy was found to be as high as 382 MPa, which is 10% higher than that of RS P/M alloy. The improvement in mechanical properties is mainly attributed to the combination effects of Orowan mechanism and coefficient of thermal expansion (CTE) mismatch because of the approximately same average grain size.