LPBF-M manufactured Zr-based bulk metallic glasses coated with magnetron sputtered ZrN films

Abstract

The fabrication of Zr-based bulk metallic glasses (BMGs) by means of laser powder bed fusion of metals (LPBF-M) is recently emerging. This production route allows to widely overcome current geometrical restrictions of casting routes while maintaining the amorphous character, which is decisive for the unique mechanical properties, for instance. However, the roughness of the LPBF-M fabricated BMGs is still a challenging property, impeding the application of near-net shaped thin films that modify BMG surfaces, e.g. with respect to wear resistance.Zr59.3Cu28.8Al10.4Nb1.5 (at.%) substrates were manufactured by means of LPBFM, applying various exposure strategies, including laser remelting of the last solidified layer to influence the surface topography. Furthermore, BMG substrates were post-treated by grinding and polishing. Thus, varying degrees of crystallinity as well as surface roughness states were generated to analyze the effect of these characteristics on the microstructural properties of additionally applied magnetron sputtered ZrN films. Substrates that were fabricated with higher energy densities during LPBF-M exhibited (101)-Zr as well as (013)- and (110)-CuZr2 phases, which were accompanied by a decreased surface roughness. It was shown that all films had a crystalline structure on amorphous and partly crystalline BMG surfaces. A decreased surface roughness of the BMG substrates could be directly correlated with a higher hardness and a better adhesion of the ZrN film.