Elimination of extraordinarily high cracking susceptibility of ZK60 Mg alloy fabricated by laser powder bed fusion.

• The hot cracks are eliminated in the LPBF-processed ZK60. • The grain size is significantly reduced after the powders modified by Y. • The grain boundaries are strengthened by the I - phase. • The cracks in LPBF-processed ZK60 samples are attributed to the Mg 7 Zn 3. The hot cracks of laser powder bed fusion (LPBF) processed ZK60 components were eliminated by adding rare earth element Y. The cause of the cracks in the samples and the suppression mechanism were analyzed in detail. The cracks in ZK60 LPBF samples were mainly caused by the low-melting eutectic phase Mg 7 Zn 3 at the grain boundaries. The average grain size decreased from 7.2 μm to 2.0 μm after adding Y. The I-phase with excellent thermal stability strengthened the grain boundaries. The elimination of cracks was mainly attributed to the I-phase at the grain boundary and the grain refinement. [ABSTRACT FROM AUTHOR]