Interfacial characteristics and diffusion mechanism in AlTiCrNiCu light-weight high entropy alloy and 1060Al prepared by spark plasma sintering

Interfacial diffusion mechanisms between light-weight high entropy alloys (LHEA) and aluminum (Al) alloys have recently gained significant attention. In this study, AlTiCrNiCu LHEA with a density of 6.3 g/cm(3) and AlTiCrNiCu LHEA/106Al system were fabricated by spark plasma sintering. Results showed that AlTiCrNiCu LHEA primarily consists of Cr-poor (BCC1), Cr-rich (BCC2), and Cu-rich (FCC) phases. As temperature increased, the interface between AlTiCrNiCu LHEA and 1060Al evolved from mechanical bonding to metallurgical bonding, and finally to diffusion bonding. Correspondingly, the thickness of the interfacial diffusion layer (which is distinct from the microstructures of the AlTiCrNiCu LHEA and Al in this system) increased linearly, reaching a maximum value of approximately 46 mu m at 833K. The diffusion layer contained complex phases, including Al3Ni2, AlNi, Al3Ti, Al2Cu, Al4Cu9, and Ni-3(AlTi) intermetallic compounds. The shear strength of the AlTiCrNiCu LHEA/1060Al joints peaked at similar to 93 MPa at 813K, due to the alternating growth mode of the interface network and the formation of brittle phases in the interfacial diffusion layer.