Structural periodicity in laser additive manufactured Zr-based bulk metallic glass

Abstract

Additive manufacturing of bulk metallic glasses (BMGs) allows for effective bypassing of critical casting thickness constraints for glassyalloys, opening up this exciting material class to new applications. An open question is how the laser processing of such materials affects theshort-range structural order, a critical mediating parameter for glass deformation. Synchrotron X-ray microdiffraction was used to under-stand structural heterogeneity across the build-planes of a selective laser melted Zr-based BMG. While negligible macroscopic heterogeneityin the structure was observed over a 10 mm build height for the X-ray amorphous material, small periodic variations were observed on theorder of 40–80 $\mu$m. This dimensional scale was rationalized as a consequence of melt-pool solidification from laser processing, which impartsa calculated local strain variation of $\pm$ 0.1%. It is anticipated that this structural insight will help to rationalize microscale deformation effectsfrom the periodic structural variation of selective laser melting produced BMGs