Processability and interfacial characteristics in PBF-LB/M-processed nano-B4C/AlSi10Mg composites with superior high-temperature mechanical performance

Abstract

Incorporating nano-scaled ceramic particles into additively manufactured Al-alloys is a validated strategy to simultaneously enhance the elevated-temperature mechanical properties and laser powder bed fusion (PBF-LB/M) processability. While B 4 C exhibits outstanding thermal stability and interfacial compatibility with Al, the integration of nano-B 4 C into Al alloys through PBF-LB/M remains insufficiently investigated. In particular, the underlying mechanisms governing laser-particle interaction, processability, and the consequent microstructural formation have not been comprehensively explored. This study aims to address this gap by investigating the effect of nano-B 4 C additions (1, 3, and 5 wt.%) to AlSi10Mg on PBF-LB/M processability and the alloy behavior. The results demonstrated excellent PBF-LB/M processability of the B 4 C/AlSi10Mg composites at all weight fractions of B 4 C. The as-built B 4 C/AlSi10Mg revealed a remarkable columnar-to-equiaxed transition, featuring an ultrafine grain structure (as small as 1.23 μm) with almost random crystallographic texture. This grain refinement was attributed to a reactive nucleation process, where the interfacial reaction between B 4 C and the matrix results in the coherent AlB 2 core-shell structured phase. Furthermore, this interfacial reaction induced a novel morphological transition, characterized by the spheroidization of irregularly shaped nanoparticles as a consequence of partial reactive melting. The B 4 C nanocomposites exhibited superior elevated-temperature mechanical properties, increasing tensile strength by up to 60% compared to their AlSi10Mg counterparts. This study provides fundamental insights into the design and PBF-LB/M processing of Al-based metal-matrix nanocomposites (AMMNCs) for high-temperature applications. • Nano-B 4 C/AlSi10Mg shows superior PBF-LB/M processability, including 5 wt.% B 4 C conditions. • Reactive nucleation stimulates a full columnar-to-equiaxed grain transition. • Irregularly shaped nano-B 4 C undergoes spheroidization induced by partial reactive melting. • Melt pool evolution is altered by several counteracting heat transfer mechanisms. • Tensile strength at 300 °C increases by 60% over AlSi10Mg while maintaining 11% total elongation.