Synergistic enhancement of mechanical strength and thermal conductivity in a novel Al-Mg-Si-Zr-Ce alloy fabricated by powder bed fusion-laser beam
Li Zhang, Zhengzhen Lu, Li Cao, Jianhong Wang, Jinfang Zhang, Xiaohui Yang, Yuankui Cao, Bin Liu, Xiaofeng Li
Abstract
• A nearly full dense Al-Mg-Si-Zr-Ce alloy was fabricated via 1 wt% ZrH 2 addition during PBF-LB. • T6 simultaneously enhanced the strength and thermal conductivity of the PBF-LB prepared Al-Mg-Si-Zr-Ce alloy. • The synergistic improvement is primarily attributed to the bimodal grain structure resulting from T6 treatment. To address the growing demand for lightweight thermal management solutions, this study presents a novel Al-Mg-Si-Zr-Ce alloy designed for powder bed fusion-laser beam (PBF-LB), achieving exceptional synergy between mechanical strength and thermal conductivity through composition design (including Zr microalloying) and systematic process optimization. By incorporating 1 wt% ZrH 2 during PBF-LB processing, a high relative density of 99.49% was achieved. The original coarse columnar-grained structure of the base alloy was transformed into a bimodal microstructure of equiaxed grains and refined columnar grains for the Zr-modified alloy. Microstructural analysis reveals that this transformation originates from two key factors: the formation of primary Al 3 Zr particles acting as effective heterogeneous nucleation sites, and the preferential precipitation of Mg 2 Si phases along short columnar grain boundaries. Post-T6 treatment resulted in remarkable property improvements, with yield strength increasing by 50.5% and thermal conductivity elevating by 63.3%. The mechanical strengthening derives from synergistic grain refinement effects and precipitation hardening, while the enhanced thermal transport properties are attributed to reduced lattice distortion in the Al matrix and optimized precipitation distribution. This work provides fundamental insights into microstructure-property relationships in additively manufactured Al alloys, offering a viable pathway to overcome the traditional conductivity-strength dichotomy in thermal management materials.