Microstructure and mechanical properties of in-situ sub-micron TiB2/7055 matrix composites have been investigated by OM（optical microscope）

SEM（scanning electron microscope）and XRD（X-ray diffraction）.The results indicate that uniform particle with 200～500 nm in size can be generated in 7055 aluminum matrix composites with 12% TiB2 content in volumetric fraction prepared by salt-mixture method.Appropriate Mg addition can greatly restrict the agglomeration of the TiB2 particles as a result of improving interface wettability between TiB2 particles and aluminum matrix

which can be responsible for the composites with the tensile strength of 718MPa

yield strength of 679MPa and elongation of 4.2% as well as elastic modulus of 86GPa.Fracture morphology of the composites is characterized by ductile mode

and failure of TiB2 particle with matrix interface is controlled by debonding mechanism.