Forming feasibility and interface microstructure of Al/Cu bimetallic structure fabricated by laser powder bed fusion

Abstract

PurposeThe purpose of this paper is to analyze and investigate heat accumulation caused by temperature changes and interface microstructure effected by element diffusion.Design/methodology/approachAl/Cu bimetallic structure is initially manufactured through laser powder bed fusion process. To minimize trial and error, finite element modeling is adopted to simulate temperature changes on the Al-based and Cu-based substrate.FindingsThe results show that forming pure copper on Al-based substrate can guarantee heat accumulation, providing enough energy for subsequent building. The instantaneous laser energy promotes increase of diffusion activation energy, resulting in the formation of transition zone derived from interdiffusion between Al and Cu atoms. The interface with a thickness of about 22 µm dominated by Kirkendall effect moves towards Al-rich side. The interface microstructure is mainly composed of a-Al, a-Cu and CuAl2 phase.Originality/valueThe bonding mechanism of Al/Cu interface is atom diffusion-induced chemical reaction. The theoretical basis provides guidance for structural design and production application.