Microstructure and tensile properties of droplet-on-demand additively manufactured AlSi7Mg

A key barrier to industrial implementation of droplet-on-demand liquid metal jetting is the limited knowledge of process-properties relationships for printed components. Herein we investigate the influence of two key parameters; baseplate temperature and infill rotation angle, on the densification, microstructure, and tensile properties of AlSi7Mg parts produced via magnetohydrodynamic-based liquid metal jetting additive manufacturing. Adjusting the baseplate temperature from 220 degrees C-500 degrees C resulted in substantial variation in the densification, microstructure, and mechanical properties of the printed material, however, infill rotation angle had a minimal influence over these characteristics. Higher baseplate temperatures resulted in higher densification, coarsened precipitates within the microstructure, as well as greater hardness and tensile strength in the as-printed condition. Greater than 99% dense samples were fabricated with a unique hierarchical grain structure (20-40 mu m) and relatively high ductility (> 15%) in the as-printed condition when processed on a 420 degrees C baseplate. Our results aid in understanding the role that key process parameters play in determining the microstructure and properties of parts produced using liquid metal jetting towards industrial adoption.