Research on Microstructure and High-Temperature Creep Behavior of In-Situ (ZrB 2 +Al 2 O 3 )/AA6016 Nanocomposite

In this study, to improve the creep property of 6016 aluminum alloys, in-situ ZrB 2 and Al 2 O 3 nanoparticles were introduced by the direct melt reaction method. The microstructures and creep behaviors of the in-situ (ZrB 2 +Al 2 O 3 )/AA6016 composites were studied. A clean and tightly bound interface between the particles and matrix is observed. The relationships between Al 2 O 3 and ZrB 2 nanoparticles with α -Al are the coherent and semi-coherent relationships, respectively. In comparison with the matrix alloys, the composites exhibit lower steady creep rates, about 3–18 times lower, and higher threshold stress. For the matrix alloys and composites, the dislocation climb mechanism is indicated by the true stress exponent of 5. After the creep test at 200 °C/70 MPa, the grain size in the 3 vol. % composite is about 68 µm, which is smaller than that in matrix alloy (156 µm). After the creep test at 200 °C/70 MPa, the diameters of the θ′ and β phases in the matrix alloy are 26 nm and 201 nm, and the fabricated 3 vol. % composite shows smaller diameters (17 nm and 168 nm) and higher density.