Microstructure and mechanical properties of B₄C/2024Al functionally gradient composites

In this research, a kind of 70-47-25% B₄C/2024Al functionally graded materials (FGMs) were prepared by squeeze casting. The interfacial microstructure, precipitate characteristics and mechanical properties of B₄C/2024Al FGMs were mainly studied. It was found that there was a small amount of interfacial reaction between B₄C particles and Al. Mg and O elements segregated at the Al-B₄C interface and MgO was formed. Under the same heat treatment conditions, the types and sizes of precipitates in different gradient layers were found to be different. Different amount of Mg segregation at the B₄C-Al interface resulted in different proportion of Cu and Mg in 2024Al matrix and it makes the precipitation regions of 25 vol%, 47 vol% and 70 vol% B₄C/2024Al locate in S, θ + S and θ respectively. The test results of basic properties indicated that the strength and plasticity of 70-47-25% B₄C/2024Al FGMs show gradient changes. The bending stresses of 70%, 47% and 25% B₄C/2024Al composites can reach 591.5 MPa, 953.4 MPa and 700.7 MPa respectively. And the elastic modulus are 240.3 GPa, 170.9 GPa and 130.7 GPa respectively. The results of this research will provide theoretical guidance for the interface structure design and heat treatment process of high strength B₄C/Al composites.