Laser powder bed fusion of an ultrafine microstructural in-situ TiB2/Al composite with excellent mechanical properties and thermal stability at elevated temperatures

Abstract

Additive manufacturing of lightweight and heat-resistant aluminum-based materials has received ever increasing interest for obtaining high specific strength and complex-shaped components serving at elevated temperatures in aerospace industry. In this study, an in-situ TiB2 particle reinforced Al–Cu–Mg–Fe–Ni (Al2618) alloy was additive manufactured by laser powder bed fusion (L-PBF) with excellent printability. The as-printed TiB2/Al2618 composite presented a fully equiaxed and remarkably refined grain structure with an average size of ∼1 μm. The intermetallic phases in the Al matrix exhibited an ultrafine cellular structure owing to the rapid solidification by L-PBF. The ultrafine microstructure showed excellent thermal stability at elevated temperatures due to the synergic effects of TiB2 particles and Fe, Ni-rich coarsening-resistant intermetallic phases. The L-PBF TiB2/Al2618 composite has shown superior mechanical performance at elevated temperatures both in tensile strength and in strength retention after thermal exposure among typical L-PBF and wrought Al alloys. This work inspires the design of heat-resistant metal matrix composites (MMCs) with advanced high-temperature mechanical performance enabled by additive manufacturing for potential industrial applications.