Tensile deformation behavior of a sub-micrometer Al2O3/6061Al composite

A 0.3 μm Al2O3/6061Al composite with 33% volume fraction of Al2O3 was fabricated by the patented squeeze-casting technology. The tensile properties were studied, and the dynamic tensile deformation behavior was investigated by an in situ TEM tensile technique. The as-cast composite exhibits excellent tensile properties with a fracture strength of 504 MPa, and the strength increases to 579 MPa after a T6 treatment. The high strength is mainly attributed to the dispersion strengthening effect of the finer sub-micrometer Al2O3 particles. Dynamic transmission electron microscopy indicates that micro-cracks initiate and propagate mainly in the matrix. The Al2O3 particles can hinder the growth and deflect the cracks, but the resistance of the particles to crack propagation is small. The propagation stage is accordingly short, leading to the fracture of the composite.