Microstructure and mechanical performance of zirconium, manufactured by selective laser melting

Abstract

Additive manufacturing as an innovative material fabrication technique has been attracting increasing attention from academia and industry in recent years. However, intensive studies on additive manufacturing of zirconium and its alloy are very scarce due to the challenge of fabrication technology. Herein, commercially pure zirconium (CP–Zr) components with high mechanical properties in terms of strength and plasticity were successfully manufactured by selective laser melting (SLM) under an argon atmosphere. The microscopic characteristics and mechanical properties of as-processed CP-Zr were comprehensively investigated by the means of optical microscope (OM), transmission electron microscope (TEM) and universal tensile testing machine. The characterization experiments indicated that the as-built microstructure of CP-Zr was composed of a large amount of ultra-fine α' martensite locating inside the columnar prior β grains, and massive dislocations and twins distributing in martensite or matrix. Based on the tensile testing, the as-built samples achieved a great ultimate tensile strength of 746.3 MPa and a high elongation of 27.1%. Due to the formation of ultra-fine microstructure and the synergistic effect of dislocations and twins, the strength and plasticity of as-built objects are 96% and 69% higher than the wrought CP-Zr cubes required in ASTM-523, respectively. In this work, a near-net shape method was innovatively proposed for fabricating zirconium and its alloy components. As well, a perspective insight was provided for investigating the strengthening and deformation mechanism of SLM-manufactured CP-Zr.