Grain refinement and performance enhancement of laser powder bed fusion in-situ processed Al-Mg alloy modified by ScH3 and ZrH2

作者：Li, Xiang; Liu, Yunzhong^*; Zhou, Zhiguang

来源：Materials Characterization, 2022, 190: 112068.

DOI：10.1016/j.matchar.2022.112068

• Laser powder bed fusion
• AlMgScZr alloy
• ScH3
• ZrH2
• Grain refinement
• Tensile properties

Laser powder bed fusion (LPBF) fabricated Al-Mg alloys, especially the novel Sc and Zr modified Al-Mg alloys, have gained popularity due to lightweight applications. In this study, low energy ball-milled mixtures of (ScH3 + ZrH2)/AlMgMn powder composites (AlMg/ScZr) and pre-alloyed AlMgScZr (AlMgScZr) powder feedstocks were used for LPBF, respectively. The processability, microstructure and mechanical properties were in-depth investigated and compared. Results indicated that a nearly full ultrafine equiaxed grain structure formed in in-situ fabricated AlMg/ScZr composites samples, due to the in-situ Al3(ScxZr1_x) particles formation which acted as heterogeneous nucleation sites. In contrast, a heterogeneous grain structure consisting mainly of coarse columnar grains was formed in the pre-alloyed AlMgScZr alloy. Tensile properties showed that the in-situ fabricated AlMg/ ScZr composites alloy had exceptional strength and ductility as compared to pre-alloyed AlMgScZr. Based on the improved mechanical properties, the underlying strengthening mechanism of the LPBF-fabricated composites alloy was discussed. The achieved properties are comparable to or higher than previously reported LPBFprocessed pre-alloyed AlMgScZr and other Al alloys. This work helps pave the novel way for designing new Al-Mg-Sc-Zr alloys applying to LPBF and other additive manufacturing technologies.