Effects of process parameters on the mechanical properties of additively manufactured Zr-1Mo alloy builds.

In order to solve the artifact problem in magnetic resonance images, a low magnetic Zr-1Mo(wt%) alloy with high mechanical performance was successfully fabricated by laser powder bed fusion (L-PBF) using gas-atomized Zr-1Mo alloy powder. The as-built Zr-1Mo alloy showed superior strength and elongation compared to the as-cast Zr-1Mo alloy due to grain refinement and the inexistence of large casting defects. The microstructure of L-PBF-processed Zr-1Mo alloy builds was not sensitive to process parameters. On the other hand, morphology and distribution of defects, interstitials concentration, and crystallographic orientation comprehensively influenced the mechanical properties of the builds. Increasing interstitials concentration caused by increasing energy density render to increasing strength. Large pores caused by balling effect lead to a severe decrease of both strength and ductility of builds using high energy density (over 70.3 J·mm) and high scanning speed (1050/1200 mm·s). On the contrary, spherical pores possessing several microns in size has much less effect on mechanical properties than the large-size pores. There are two kinds of texture({1 1 0} texture and {1 1 0}+{1 0 2} bi-texture) were confirmed in this study. {1 1 0} texture contributed to the slight increase of elongation with increasing energy density in low scanning speed case (600/750 mm·s) and the superior elongation of low scanning speed specimens compare to that of high scanning speed specimens in medium energy density range (about 48 J·mm). From the viewpoints of the ultimate tensile strength(UTS) and elongation, it was found that an energy density of 84.4 mm·s with a scanning speed of 600 mm·s is preferable for the L-PBF-processed Zr-1Mo alloy in this study. These experimental results may provide direct guidelines regarding the applicability of Zr-1Mo alloy fabricated by L-PBF for biomedical applications.